1 UserManual e
1 UserManual e
DETECTION TOOLS
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Electronics For Industry, Inc.
6850 SW 79 Terrace
South Miami, Florida 33143-4440
305-233-1640 voice
305-666-4185 fax
sales@e4i.com e-mail
www.e4i.com web site
Version NOV2010
User manual
2
INDEX
SECTION 1 - QUICK START
This section is for those who are familiar with Ultrasound
characteristics and have some familiarity with Ultrasonic
Testing Tools.
SECTION 6 – ELECTRICAL 42
ELECTRICAL EQUIPMENT ANALYSIS USING ULTRASOUND (42-44)
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SECTION 1 - QUICK START
Insert the Leak Detection Module (the one with the grill opening at the front)
into the recessed front of the Detector body. Be sure that both connector
pins line up with the receptacles and that the Module seats fully in the recess.
Plug the headset cord connector into the receptacle in the bottom of the
“grip” of the gun. You are now ready to search for leaks of any gas or vapor
that is under pressure or vacuum.
To remove the Leak Detector module, pull it straight out from the pistol body
and store it in the storage slot in the die cut foam.
If the meter jumps too rapidly and bangs against the full-scale side of the
meter it may be desirable to reduce the meter sensitivity. Meter sensitivity is
adjusted by inserting the adjusting tool (small red screwdriver which came
with the kit) into the hole on the left side of the pistol body and setting the
desired meter sensitivity. This adjustment does not affect the detection
ability of the unit, only the meter sensitivity.
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The leak detector is directional and you can follow it directly to a leak. As
you approach a leak point the meter may remain at full scale and/or you will
not be able to hear a difference in the sound level. When this occurs, start
reducing the sensitivity to keep the meter on scale. Continually reduce the
sensitivity until the leak point is pinpointed. If it is still too sensitive you can
additionally reduce the sensitivity by turning the module sensitivity
adjustment located on the top of the black module itself counterclockwise
using the black plastic screwdriver which came with the detector kit.
If when using your leak detector you find the unit is too sensitive, (the meter
remains at full scale), when the volume sensitivity knob is all the way down,
sensitivity can be reduced further by reducing the sensitivity of the Leak
Detector Module itself by adjusting the potentiometer located in the module
itself. Use the black plastic screwdriver supplied with your kit to turn down
the control through the hole on the top side of the module just forward of the
red housing until the meter remains on scale or until the desired sensitivity is
set.
Tubular Style Detector
Finding leaks with the Tubular Style detector is the same as when using the
Pistol Style detectors. The difference is that the tubular units do not have a
meter nor do they have plug in front end units, they are complete and self
contained. The rotary control on the top of the unit is the on off and
sensitivity control. After plugging a headset into the receptacle on the rear of
the detector you then rotate the control forward to turn it on and set the
sensitivity and volume level. Now the search is the same as described above.
Be sure to turn the unit off when not in use to conserve battery power. The 9-
Volt battery is located under the cover toward the rear of the detector unit.
Unscrew the two slotted head machine screws to access the battery.
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TONE GENERATOR USE
The Tone Generator should be placed inside the enclosure. The interior
becomes “filled” with high frequency sound, which will leak through any
openings. Scan the surface, seams and seals with the detector, using the
leak detector module. Anywhere there is a leak the tone will be heard. As
stated before the leak source is the loudest point and as you approach the
source you may need to reduce sensitivity in order to pinpoint the exact spot.
Do not point the detector directly at the tone generator as the energy is so
intense it my block the detector, it will not harm the detector but you will not
hear any tone.
To test the Tone Generator, turn it on and point the detector away from the
Tone Generator when pulling the trigger on the detector.
The ultrasound produced by the Tone Generator is quite intense and can
cause a “Drum Head” type of transmission of energy if the enclosure is a thin
material, you can dampen this with a rag pressed lightly against the outer
side of the “can” being sure not to cover seams or seals.
Ultrasound will not pass through a solid so the “leak channel” must be dry as
water in the air path appears as a solid to the ultrasound. This is especially
true when looking for leaks in automobile windshields or roof leaks.
The following diagrams are examples of how the tone generator is used to
find leaks in various types of volumes but is by no means a complete list of
its uses.
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Tone generator capacity for a closed
volume with hard reflective surfaces
and no blocking obstructions such as
baffles is approximately 1500 cubic feet
and is omni directional.
Directional Application:
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OPERATION AS A MICROSONIC STETHOSCOPE
Insert the Stethoscope Module (the one with the metal probe extending from
the front) into the recessed front of the Detector body. Be sure that both
connector pins line up with the receptacles and that the Module seats fully in
the recess. Be sure the metal probe is screwed into the front of the module
only “finger tight”. Over tightening could result in internal damage to the
Stethoscope Module.
If when using your stethoscope you find the unit is too sensitive, (the meter
remains at full scale), when the volume sensitivity knob is all the way down,
sensitivity can be reduced further by reducing the sensitivity of the
Stethoscope Module itself by adjusting the potentiometer located in the
module itself. Use the screwdriver supplied with your kit to turn down the
control through the hole on the side of the module until the meter remains on
scale.
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As wear begins in machinery, ultrasonic sound from increasing friction is
building up long before the unaided ear can hear it. The Stethoscope is
valuable because of this. It forewarns you. The repair or maintenance can be
carried out at a more convenient time; rather than waiting for failure that
always occurs at the most inopportune time. Furthermore, damage is often
more severe during later stages of failure.
Since high frequency vibrations do not radiate as much as low frequency
vibrations, use of the Microsonic Stethoscope allows you to more readily
screen out some sounds and pay particular attention to others.
Finding mechanical troubles with the Tubular Style Stethoscope is the same
as when using the Pistol Style Stethoscope. The difference is that the tubular
units do not have a meter nor do they have plug in front end units, they are
complete and self contained. The rotary control on the top of the unit is the
on off and sensitivity control. After plugging a headset into the receptacle on
the rear of the detector you then rotate the control forward to turn it on and
set the sensitivity and volume level. Now the search is the same as
described above for the Pistol Style Stethoscope. Be sure to turn the unit off
when not in use to conserve battery power. The 9-Volt battery is located
under the cover toward the rear of the detector unit. Unscrew the two slotted
head machine screws to access the battery. An additional sensitivity control
us located under the battery to further reduce sensitivity of you find the unit
too sensitive.
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SECTION 2 - EFI DETECTION KITS
It is highly recommended that you use the headset when using your detector.
Listening as well as keeping your eyes on the meter, as much as is safe,
makes a search easier. The additional information you get, frequency,
repetition rate, and sound discrimination makes locating and pinpointing
problem areas much quicker. The meter displays only the sum of all the
sounds. However, use of the headset is not absolutely necessary; the
headset does not even have to be plugged in for operation of the pistol style
detector.
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PISTOL STYLE DETECTORS
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TUBULAR STYLE DETECTORS
KIT CONTENTS
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KIT CONTENTS
MODEL W-7 "Microsonic Detection Kit" consists of the Pistol Style
Detector, Leak Detection Plug in Module, Stethoscope Plug in Module,
Rubber Focusing Extension, Tone Generator, Deluxe Headset, Carrying Case,
Stethoscope Sensitivity & Meter Adjust tools, This manual on a CD and
batteries.
MODEL W-5 "Wind Noise Test Set" consists of the EI-500 Tubular Style
Detector, Tone Generator, Rubber Focusing Extension, Headset (Specify
Light-Weight or Deluxe), and carrying case or carrying pouch depending on
which headset option is selected.
MODEL EI-500 " Microsonic Leak Detector" consists of the Tubular Style Leak
Detector, a Headset (Choice of Light-Weight or Deluxe), and a carrying case if
the Deluxe Headset is chosen or pouch if the Light-Weight headset is chosen.
There are several accessory items that are available such as:
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MSM-1 "Magnetic Stethoscope Module". A module that plugs into the front
end of the Pistol Style Detector with a five foot cord
leading to the actual Stethoscope Module which has a
rare-earth magnet assembly on the front to allow it to
be magnetically attached to the piece of machinery
being listened to. This is especially useful when the
operator needs both hands free such as when using a
grease gun to inject grease in a bearing and listening for the lowest sound
point which indicates the optimal grease point.
Technical Specifications
Item Weight Housing Length Width Power
TG-2 Tone Generator 6.3 oz ABS-T1000 Plastic 5.5" 2.5" (4) 1.5V AA
Light Weight - - -
0.7 oz
Headset SH-1 Molded Plastic
Please include a short note describing your problem or troubles. Your unit will be
serviced promptly and returned to you. If it is a warranty repair please include proof
of purchase.
For more information please visit our web site at: http://www.e4i.com
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(Sample)
CERTIFICATE OF CALIBRATION
George A. Harris
President
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SECTION 3 - INTRODUCTION TO ULTRASOUND
What is Ultrasound?
Sound has been defined as vibration of an air column to which a human ear
would respond. Ultrasound is those frequencies that are above human
hearing. Humans can usually begin to hear low frequency sound at about 30
Hertz (cycles per second). This is comparable to the low bass frequencies in
a good music system. The upper range for high frequency hearing is usually
in the neighborhood of 15,000-20,000 Hertz or 15 to 20 Kilohertz. Near either
end of this range, hearing sensitivity has decreased significantly; sound has
to be louder to be heard. Maximum human hearing sensitivity is in the 2,000
to 4,000 Hertz range, which includes most speech frequencies.
Even though we humans don't have much sensitivity to the higher (or to us,
ultrasonic) frequencies, these sounds exist in nature. Bats use high
frequency sonar to zero in on flying insects at and after dusk. Crickets rub
their legs together and generate considerable high frequency noise as part of
the chirp that we hear. (It is interesting to listen to crickets or bats with an
EFI leak detector.) Some species of fish use very low frequencies for
communication of a sort, and others use high frequencies. Rodents can
communicate at frequencies far above our hearing range, up to 100,000 Hertz.
Dogs and cats have high frequency hearing sensitivity above our limits. The
so-called "silent dog whistles" generate high frequency sound that dogs can
hear but humans cannot.
As the frequency (or pitch) of sound rises toward and beyond our upper
hearing limit, its characteristics change considerably. If the source is
“directional”, such as inside a room with an opening, the low frequencies
tend to spread out from the opening (source) of sound. High pitch sounds
tend to form more of a beam, and the effect is more pronounced as the pitch
rises. Higher frequencies are more directional. We know that if a sound
source is distant, it does not sound as loud (the intensity is lower).
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Fluid and gas systems and other working machinery have constant
ultrasound patterns. When a leak occurs, the fluid passing through produces
turbulence with strong ultrasonic components. Changes in the "sonic
signatures" can be readily recognized as wear in components. An ultrasonic
detector senses subtle shifts in the signature of a component and pinpoints
potential source of failure before they cause costly damage.
These lightweight tools are battery powered, so operators can easily move
from machine to machine. Their circuitry translates the high-pitched
ultrasounds to those in the human hearing range, enabling users to hear a
mirror image of the ultrasounds through headphones and gauge their
intensity by the increase in sound in the headset and increasing reading on
an analog meter.
Any ultrasonic tool should be checked for an intrinsically safe rating before it
is used in hazardous areas.
EFI started production of its line of leak detector tools in the early 1960's.
Then, as even now, the only generally practical alternative to these tools for
locating leaks is the slow, inconvenient painting of suspected leak areas with
soapy water, then watching for bubbles to appear. The EFI detectors are
extremely sensitive to the ultrasonic noise generated by leaking pressurized
air (or other gas, including steam), but they are as insensitive to ordinary
noise as our ears are to ultrasonic noises. The detectors convert ultrasonic
sound waves down to sounds that we can hear with our ears. This is similar
to the way radios convert radio waves to audible sound.
We all know that a gas/air leak generates noise; sometimes we can hear it.
Whether we can hear it or not depends on many factors. Some of those
factors are the amount of other noise in the vicinity to mask it, the size of the
leak, characteristics (especially the size and shape) of the hole that allows the
leakage, the type of material, and the pressure that forces the gas out of the
hole.
Leaks generate ultrasonic noise as well as noise that we can hear with our
ears. The problem with listening for leaks is that our ears are not sensitive
enough, especially for small leaks. They are not very directional due to their
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design and purpose. Another problem is that there is almost always some
normal or machine noise in the vicinity, which would mask the leak source
sound.
Using a leak detector to listen for the ultrasonic signature of a leak is far
superior to using our ears to locate leaks.
Ultrasonic detectors can be made much more sensitive than the ear to detect
leaks. Ultrasonic noise is also much more directional, making it easier to find
the leak vicinity, move closer, and then pinpoint the source. In general, there
is not much ultrasonic background noise to mask the leak noise. If there are
other sources of ultrasonic noise, they are usually widely enough scattered
to be unimportant, since ultrasonic noise is absorbed much more as it
passes through a distance in air than is normal noise.
Suppose now that the same system is drained and dry, and is pressurized
with air. The spot that was damp might or might not generate ultrasonic
noise. Increasing pressure would increase the likelihood of detection. The
source of the drip would probably be easy to detect. The air does not have
surface tension, and there would be a small steady leak from the hole. As the
air escapes from the holes, there would be turbulence and noise generated.
As the pressure increases, noise increases. The hole that had a very fine
stream of water should generate lots of noise and be detectable at a
considerable distance.
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Remember that this noise is generated at the point where gas is liberated
from the higher-pressure area (inside the hose, through the hole) and out into
the lower pressure area. As the higher pressure leakage passes into lower
pressure outside, turbulence results, which creates the noise.
In the case of the faucet or any valve, and sometimes with threaded fittings, a
different condition can exist. The high to low pressure transition can occur
inside the structure, at the valve seat itself. This is the point of maximum
energy and maximum sound generation. The sound then must travel through
the air path following the threads or down the hose to the exit point, losing
energy as it travels.
An example of this would be a welding tank where the valve has not closed
completely. The leak is actually at the valve seat, this is the point of
maximum energy. The sound now travels down the hose, losing energy as it
travels, to the welding tip which is a much larger opening and also disburses
the energy instead of concentrating it as a smaller hole would. The result is
often less noise than would be expected, requiring the detector to be closer
to the leak.
A similar example is to hold the detector opening a couple inches from one
eye and then blink the eye rapidly. The friction of the eyelashes rubbing
together generates the noise. Yet the detector does not react to ordinary
sound in the vicinity. You do not hear people talking or machinery running.
Leaks generates noise. Sometimes we can hear it with our ears, sometimes
not. Whether we can hear it or not depends on many factors such as:
1. The amount of other noise in the vicinity to mask it.
2. The size of the leak.
3. The characteristics (size and shape) of the hole that allows the leakage.
4. The type of material and its thickness.
5. The pressure or vacuum that forces the gas in or out of the hole.
Turbulence is produced as fluid or gas moves from high to low or low to high
pressure. This turbulence contains strong ultrasonic energy that is
detectable by the EFI detection units. This ultrasonic emission, once
detected, is heterodyned (shifted in frequency) into the audible range where it
can be heard by the human ear through earphones or viewed as an analog
readout on a meter.
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Time and convenience are also improved with ultrasonic detection since
equipment may be tested and leaks located while on-line and all the
machinery is still operating.
It can be generally noted that the larger the leak, the greater the ultrasound
level.
Using the leak detector, with the sensitivity set at maximum, scan the general
area of a suspected leak by waving the detector back and forth and listening
for an increase in the hissing sound, (similar to the sound you hear when you
fill a tire with air), in the headset and/or a peaking of the meter reading. Move
in the direction of the loudest sound. If it is hard to determine the direction of
the loudest sound, reduce the sensitivity until direction can be established.
Follow the sound and continue to reduce the sensitivity to determine the
direction of the leak. In order to confirm the leak site, move the detector back
and forth over the suspect area. The sound level will increase as you pass
over the exact leak point. In some loud factory environments shielding of the
transducer may be required by using the rubber focusing extension or other
shielding methods as explained below.
INTERFERENCE SOLUTIONS
If there is ultrasonic interference in the vicinity of leak you are searching for,
reduce the sensitivity of the detector and work closer to the item being
tested, or try one of the following:
x 1. Turn your back to the source of interference so that the detector is
facing away from the trouble source. Ultrasound is extremely
directional and your body acts as a sound block.
x 2. In extreme cases put an "ultrasound blocker", a "sound barrier",
between the interference source and the area you are searching. An
ordinary clipboard placed to reflect the sound back in the direction of
the interference works well. A flexible curtain will absorb some of the
sound, and reflect some back toward the source of the noise. Plastic
sheeting is often used; the smooth surface is especially effective in
reflecting the sound back toward the source. It is possible to make an
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"ultrasonic soundproof" room or area in the midst of an otherwise noisy
area this way.
To confirm a leak, position the rubber focusing extension (on the leak detector
module) close to the suspected leak site and move it slightly back and forth in
all directions. If the leak is at this location, the sound will increase and
decrease in intensity as you sweep over it. In some instances, it is useful to
position the rubber focusing probe directly over the suspect leak site and push
down to seal it from surrounding sounds. If it is the leak, the rushing sound will
continue. If it is not the leak site, the sound will drop off.
x 5. Another method is to put the shop rag over the suspected leak
creating a void over the leak. Insert the end of the rubber focusing
extension (on the leak detection module) into the area of the suspected
leak. The area will be isolated from the surrounding ultrasound thus
making pinpointing much easier. Sometimes a gloved hand can create
the same effect.
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Common Sources of Interference
Computers: Computers are now found almost everywhere; they are often in
maintenance offices, and sometimes on factory floors to control equipment
or processes. Some computers and some computer displays (monitors)
generate ultrasonic noise. Transformers in both sometimes operate at an
electronic frequency comparable to that of the leak detectors. The
transformer structures can vibrate at the operating frequency and generate
ultrasonic noise. A noisy high voltage (flyback) transformer is an example.
This noise when heard using a leak detector does not sound like a leak, it
usually sounds more like a tone, buzz, or whistle. This is a good example of
where the meter reading would only tell part of the story. The meter would
read as if a leak were being detected but by listening you would be able to
identify the type of sound and know it was not a leak.
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ADVANCED METHODS OF FINDING STUBBORN OR HARD TO GET AT
LEAKS
WAVE GUIDES
When a suspected leak source has been identified by scanning an area that is
not easily accessible for leak verification, a simple wave guide can be used to
gain access to an
ultrasonic emission. A
simple wave guide can be
made from ¾ inch PVC
tubing cut to the desired
length. One open end is
extended to the suspected
area and the leak
detection unit (W7 or EI-
500) is inserted in the
other end. Ultrasonic
emission if present will
travel within the tube to
the detector. A flexible
wave guide can be made
from 1.75 inch rubber hose or the rubber focusing extension can be used.
When testing for low volume pressure leaks, apply liquid at the test area and
scan with the leak detector. For valve stems, seams, flexible materials and
seals the contact probe can be used at the suspected leak point.
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SECTION 4 - USES & APPLICATIONS
USES FOR THE TOOLS
Typical Applications:
x Pinpoint pressure and vacuum leaks of any gas, air, steam or vapor.
x Find leaks around seals, seams, welds, hatches, fittings, and bulkheads,
without pressure.
x Listen to internal, mechanical operations to predict failure or track wear
x Compressed air leaks.
x Steam systems (Traps - Valves - Gaskets - Boilers).
x Check bearings for wear and lack of lubrication.
x Motors, Pumps, Gear Boxes for internal wear.
x Electrical Systems for Arcing, Sparking and Corona.
x Hydraulic Systems (Valves, Seals, Controls).
x Drive Belts for cracks, wear and slippage.
x Enclosed Areas (Rooms, Containers, Roofs, Windows, etc.)
x Check Valves, Gaskets, Seals and Seam Leaks.
Bad spark plugs, leaking transmissions, radiator or block leaks are best
found with the Microsonic Leak Detector.
Railroads:
As the train rolls by you can hear the sounds of an airbrake
leak but not the sounds of the train itself. With the
Microsonic Detectors you can also hear a dragging brake as
the train rolls by. Once the train has stopped you use the
detector to pinpoint the exact leak spot. The Microsonic
Detectors are good for finding leaks in the Diesel system,
around injectors and gaskets. Using the stethoscope you can hear pistons
moving, individual valves opening and closing and listen to the flow at the
injectors to “hear” clogged injectors. Using the stethoscope to listen to the
internal operation for correct sequencing facilitates trouble shooting
pneumatic and hydraulic system problems.
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Bearings:
Over greasing a bearing is as bad as not greasing a
bearing. Too much grease results in too tight packing,
additional friction and pressure and heat build up. By
listening to the bearing with the Microsonic Stethoscope
while adding grease you can determine the optimum
grease point. Use the stethoscope to listen at the bearing housing and begin
pumping grease with your grease gun. As you add grease the sound
diminishes, at the optimum point the bearing is quietest, as you add still
more you will hear the sound begin to increase, stop, you have the optimum
grease. For ease of use we offer a magnetically positioned transducer to
leave both hands free while using your grease gun.
Busses:
The Microsonic Detection Tools have many uses in
Bus maintenance and repair. Air brake system
leaks are readily detected and heard. Pneumatic
system leaks or mal functions are easy to trouble
shoot. Air conditioning problems and leaks are readily found. Tire and valve
stem leaks are quickly located and pinpointed. Water leaks around the
windows, door and baggage compartment seals are easily found and repaired
and re-checked using the Tone Generator, a water test is never needed.
Pumps:
Are the valves opening and closing, as they should? Is there
cavitation? Can you hear air in the chambers or lines? Is the
pump running as smoothly as it should? Are the seals
leaking? “Hear” the problem in its early stages so there is
time to plan repairs, don’t wait for disaster to strike.
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Diesel or Gas engines:
Listen to pistons, valves, vacuum systems, head gasket
leaks. Find faulty injection systems, irregular firing as well
as carburetor and intake leaks. All these problems and
more are easy to find using the Microsonic Detectors
because you do not hear the background noise or the other noises that your
normal ear hears and that keep you from hearing and finding these problems
with your unassisted ears
Steam Traps:
Is it stuck open, is it stuck closed? Does it cycle
properly? Is my steam trap working as it should.
Listen with the Microsonic Stethoscope and you will
answer all these question with the greatest of ease.
Even with the plant noises at their highest level you can hear the “operation”
of your steam trap because the Microsonic detectors do not hear all that
other plant noise.
Boats:
Easily find where the water is entering around windows,
portholes, and hatch covers. Hull leaks and seals are
quickly checked using the Microsonic Detectors.
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Boilers and Heat Exchangers:
Boiler tube leakage or blockages can be heard by listening on
the outside of the shell in the vicinity of the tubes. Leaking or
blocked tubes generate a different sound than normally
operating tubes.
Heat exchangers of all kinds can be tested using the Tone Generator. The
tone generator is set to impinge its energy on the outside of the tubes and
the Microsonic Detector is used at the tube ends to listen for the “tone” that
will be heard where there is a holed or leaking tube. If the leak is around the
end roll then the tone will be heard around the periphery of the tube in
question. Use of the Rubber Focusing Extension is recommended to make
pinpointing easier. For very large heat exchangers the use of multiple tone
generators to create a higher level of energy around the tubes is
recommended.
Continuously running compressors means you are not getting the air (or
vacuum) to the tools that it is supposed to feed which means additional wear
on these tools or machines and loss of production time.
Easily pinpoint these leaks as you walk through your plant. Take the
Microsonic Detector with you and scan the plant as you walk. Make notes of
the leaks and then when there is time available you know exactly where to
send the repair person. Over a period of time you will clean up your plants
leaks and save many dollars.
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Aircraft:
Pressurization leaks, Pitot Static System leaks,
Instrument air or suction leaks, leaks around the
instrument faces, oxygen system leaks as well as
water leaks into the cabin or the baggage
compartment or the avionics area. Pinpoint and
stop the water incursion before serious damage
occurs. Find and fix those pesky wind noise whistles.
Using the stethoscope you can listen at the face of the gyro instruments to
tell which one is starting to have trouble, don’t wait until it fails in flight,
predict failure and fix it before it becomes critical.
Delicate Machinery:
The extreme magnification of internal sound by the Microsonic Stethoscope
allows you to hear the changes in even the most delicate bearings or
machinery. If you know what you are listening to you can even hear the
mechanism of a fine safe or lock. By listening over a period of time, you will
develop a sound pattern that is normal for you machinery. When something
starts to go bad you will know it and be able to effect repairs before the
machine is damaged or the precision work it is supposed to do is
compromised.
Hydraulics:
Using the Microsonic Stethoscope you will readily hear
malfunctioning hydraulic systems. Bypassing
cylinders, mal functioning valves and other system
problems.
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ELECTRICAL
Overhead Lines:
Hear the problem from the ground, no need to climb
the pole or tower to tell where the leak is.
Pressurization leaks in telephone overhead lines are
readily heard from the ground. Just walk the line
aiming the detector at the lines until the leak is
heard.
Electrical Discharge:
Corona Arcing and Sparking in overhead power lines and transformers and
other electrical equipment is readily detected.
Corona is heard as a 60 Hertz buzz, arcing and sparking sound like crinkling
cellophane, sparking is intermittent, arcing is continuous when heard using
the Microsonic Detectors.
Electrical problems in switch gear and substations are easily spotted. While
you are checking the sub station don’t forget to check air operated circuit
breakers and for nitrogen leaks in the transformers.
Leaking insulators cause insulator deterioration and radio and TV
interference. These corona or arcing problems can be detected from the
ground. The higher the voltage the higher the line is above the ground but
the higher the potential energy and thus the higher the ultrasonic energy that
is created allowing you to detect the problem from the ground even for the
high cross country lines.
Power Generation:
Power generating stations have most of the problems that are found
elsewhere in this document. Pinpoint Vacuum leaks,
pressure leaks, pneumatic controls, bearings, controls,
hydraulics, compressors, switch gear malfunction,
pumps, electrical corona arcing and sparking. All these
problem areas and more are areas of use for the
Microsonic Detectors.
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SECTION 5 - MECHANICAL ULTRASONICS
Mechanical Ultrasonics
ROTATIONAL EQUIPMENT PRODUCES AN ULTRASONIC EMMISION
RESULTING FROM FRICTION BETWEEN MOVING PARTS
In ball bearings; as the metal in the raceway, roller, or bearing balls begins to
fatigue, a subtle deformation begins to occur. This deforming of the metal
will produce an increase in the emission of ultrasonic sound waves. When testing,
changes in amplitude of from 12 to 50 times the original reading is indication of
incipient bearing failure. When a reading exceeds any previous reading by 12 dB,
it can be assumed that the bearing has entered the beginning of the failure mode.
Brinelling of bearing surfaces will produce a similar increase in amplitude due to the
flattening process as the balls get out of round. These flat spots also produce a
repetitive ringing that is detected as an increase in amplitude of monitored
frequencies.
Ultrasound detection tools provide information in two ways: They let the operator
hear ultrasounds qualitatively through a noise-isolating headphone that blocks out
plant noise and they display quantitative, incremental readings on a meter. The
sensitivity of the tool can be adjusted to seek out particular sounds. The
detector can even record the sound of an eye blinking.
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Avoiding costly bearing failures
Inland Empire Foods in Riverside, CA, pre-cooks, dehydrates and packages a
wide variety of beans for resale to other food processing companies. As part of
Inland's preventative maintenance program, it uses a lightweight ultrasonic
detection system to make monthly inspections of bearings throughout the plant.
Ultrasound testing allows operators to hear sounds the human ear cannot detect
under normal conditions. All operating equipment and most leakage problems
produce a broad range of sounds. The high-frequency, ultrasonic components of
these sounds have extremely short wave lengths and tend to be directional. By
pointing the ultrasonic tool in the direction of the object to be tested, the
signal is isolated from background plant noises and its location easily
detected. As subtle changes occur in mechanical equipment, the directional nature
of ultrasound permits potential warning signals to be detected before actual
equipment failure occurs.
According to plant manager Perry Sterner, "using ultrasound, we have the choice
of testing for bearing wear either during actual production or when the plant is shut
down. Wherever there is evidence of a problem," says Sterner, we use the
ultrasonic detection tool to provide confirmation of our vibration readings and
replace the faulty bearing.
"One of our biggest problems is dry bearings. Using the ultrasonic detector, we
can hear if the bearing is running dry or if there is a small particle of dirt on the ball. If
there is a flat spot on the ball hitting the raceway of the bearing, we'll hear it
randomly as the ball rotates."
Sterner schedules periodic greasing of the bearings and can listen with the
ultrasonic equipment as he pushes grease into the raceway. The meter
readings are recorded monthly and are used to indicate when the bearings need to
be replaced.
In addition to using the ultrasonic detector for predicting and preventing bearing
failure, Inland Empire Foods periodically checks for leaks in steam traps, inspects
motors for phasing problems, and checks starters for arcing with the sensitive
listening equipment.
Recently, Sterner discovered another use for his ultrasonic detector. "Our QC
department had placed a load of black-eyed peas on hold for possible
infestation and disposal. I was curious to know if the ultrasonic device could
detect the presence of insects in the tote bags. I put on the headphones and
placed the ultrasonic detector near the sack. It was amazing. You could
actually hear the insects crunching on the peas!“
Comparative Test - Use the contact (stethoscope) module. Select a test spot on
the bearing housing and mark it for future reference. Touch that spot with the
contact probe. In ultrasonic sensing, the more mediums or materials ultrasound has
to travel through, the less accurate the reading will be. Therefore, be sure the
contact probe is actually touching the bearing housing. If this is difficult, touch
a grease fitting or touch as close to the bearing as possible. For consistency,
always approach the test spot at the same angle. Reduce sensitivity until the meter
reads 20. Listen to the bearing sound through headphones to hear the quality of the
signal for proper interpretation. Select same type bearings under similar load
conditions and same rotational speed. Approach the bearings at the same
angle, touching approximately the same area on the bearing housing. Compare
differences of meter reading and sound quality.
Historical Bearing Test - Use the basic procedure as outlined above in the
comparative test. Note meter reading, and sensitivity selection on your bearing
history chart. Compare this reading with previous or future readings. On all future
readings, adjust sensitivity level to the original level recorded in the bearing
history chart. If the meter reading has moved form the original 20 mark up to or
past 100, there has been a 12 db increase. (Increments of 20 on the meter in the
linear mode is about 3 decibels; e.g., 20-40=3db, 40-60=3db, etc.) Note: Increase
of 12 db or greater indicates the bearing has entered a failure mode. Lack of
lubrication is usually indicated by an 8 db increase over baseline. It is usually heard
as a loud rushing sound. If lack of lubrication is suspected, after lubricating, re-
test. If readings do not go back to original levels and remain high, consider that the
bearing is on the way to the failure mode and recheck frequently.
Sometimes there are so many bearings in a plant that not every piece of equipment
can be checked routinely by a limited staff of trained technicians. Since ultrasound
detectors require little training, a technician or the machine operator can determine
potential bearing problems and notify the vibration technician for follow-up.
Sensitivity adjustments and calibration are essentially the same as described above
for Leak Detector use with the following added stethoscope only adjustments.
If when using your stethoscope you find the unit is too sensitive, (the meter remains
at full scale), when the volume sensitivity knob is all the way down, reduce the
sensitivity of the Stethoscope Module itself by adjusting the potentiometer located
in the module. Use the screwdriver supplied with your kit to turn down the
control through the hole on the side of the module until the meter remains on
scale.
39
The stethoscope is detecting sound generated by the friction of the parts rubbing
together, and not just the clicking sounds of the escapement, or gear wheels
meshing.
Since high frequency vibrations do not radiate as much as low frequency vibrations,
use of the Microsonic Stethoscope allows you to more readily screen out some
sounds and pay particular attention to others.
Internal flow can be heard with the Stethoscope to detect turbulence or blockage in
lines or process flow. It is easy to tell if a valve has shut completely, is leaking, or
bypassing. You can hear the action of the valve and the flow. As the valve closes
completely, flow ceases. If the valve stops moving as if closed, and flow is still
heard, the valve has not seated and sealed properly.
40
Air Compressor - Inspection
DESCRIPTION
Compressors are the heart of any
compressed gas system. Routine inspection
and maintenance can prevent unplanned
downtime. Although any type of
compressor can be inspected ultrasonically,
the most common application centers on
larger reciprocating types. Specifically,
valve function in these compressors is
critical. Minor valve leaks can rapidly lead to
large leaks, which can effect production and
impact on plant safety.
Detection Method
For the "contact' method touch the valve with the contact probe and reduce the
sensitivity until it is possible to obtain a meter swing around mid-line and hear the
valve open/close movement. When testing, be sure to compare similar valves to each
other (i.e. intake to intake, exhaust to exhaust) and under the same conditions (i.e.
idling vs. working). For additional localization, use the leak detection module with
rubber focusing extension.
41
SECTION 6 - ELECTRICAL
Electrical inspection
A person with no experience can learn to use the tool in about an hour. However, it
takes more experience to be able to identify individual sounds. Usually the operator
begins an inspection by fully opening the scale and broadly scanning the equipment.
If a noise is detected, the operator uses the tuning and directional capabilities of the
instrument to home in on the source.
42
time. Had it been operating at full load, the connections would probably have
disintegrated, interrupting power to 80,000 to 100,000 customers.
Transformer voltage taps that run hot cannot be detected with infrared
equipment because the heat from the transformer barrel is greater than that from
the loose connection. During inspection of a 1500-kVA dry transformer (Fig 3),
serious tracking and arcing was heard in the secondary voltage tap. When the
connections were dismantled, carbon buildup and arcing traces were found in the
tap contacts.
In each of these cases, problems were detected that could not have been found
without de-energizing the equipment. In some cases, even a visual inspection
would not have found the defects.
DESCRIPTION
When electrical apparatus such as switchgear, transformer, insulators or potheads
and splices fail, the results can be catastrophic. This is just as true in industrial plants
as it is in the power transmission and distribution side. Electrical discharges such as
arcing, tracking or coronas are all potential for equipment failure. In addition, the
problems of RFI and TVI impact on our valuable communication networks. All these
conditions produce ultrasound and are detected with the Ultrasonic detection
unit.
43
How Ultrasonic Electrical Detection Works
Arcing, tracking and corona all produce some form of ionization, which disturbs the
air molecules around it. The Ultrasonic unit detects the high frequency noise
produced by this effect and translates it, via heterodyning, down into the audible
ranges. The specific sound quality of each type of emission is heard in headphones
while the intensity of the signal is observed on a meter. Normally, electrical equipment
should be silent; although some may produce a constant 60cycle hum or some
steady mechanical noises. These should not be confused with the erratic, sizzling
frying, uneven and popping sound of an electrical discharge.
Detection Method
Before beginning any inspection of mid or high voltage equipment, be sure to review
your plant or company's safety procedures. Essentially, as in generic leak detection,
the area of inspection is scanned using a high sensitivity setting. As the direction is
determined and you approach the source, reduce the sensitivity until pinpointing is
possible. If it is not possible to remove covers, or plates, scan around the seams and
vent slots. Any potentially damaging discharges should be detected.
44
SECTION 7
STEAM TRAPS
x Steam Traps and Valves explained.
PREFACE
Any method used to check the operating performance of steam
traps requires experience on the part of the individual conducting
the test. The reason is that a great number of variables exist
causing many different indicators being presented to our senses.
Ultrasonic testing eliminates some of these variables allowing us to
make a more accurate determination of the indications perceived.
45
MAINTAINING STEAM TRAPS
46
difficult to determine whether a steam trap has failed just partially open,
indicating a slow leak and a developing failure. He continues, "Such
a…failure could persist for quite some time without any outward sign.
Therefore, a maintenance person should make periodic surveys of the
installed steam traps." Banyacski emphasizes that steam blowing through a
trap indicates that the trap needs to be repaired or replaced.
He points out that visual inspection requires an inspector to let a steam trap
discharge into the atmosphere. However, doing that changes the parameters
of the closed system and, therefore, can be unreliable.
Loken also says that there are enough variables in the system—
backpressure, for example—so that temperature is not the most reliable
indicator either. He recognizes, however, that portable infrared thermometers
provide close estimations of pressures on valves, traps, and coil heaters.
And he notes that these devices are also useful for spotting conditions such
as heat loss, the need for insulation, overheating, overloads, and cooling
failures. Thus, he recommends that an infrared thermometer be used along
with ultrasound.
Agreeing with Banyacski, Loken says that traps that have failed completely
open are easy to detect, but he points out that the object is to find failing
traps before they fail completely. Ultrasonic testing can do that. "In essence,
using an ultrasonic instrument is like putting the inspector inside the steam
trap and piping system, allowing him to detect a leaking steam trap," Loken
says. "Ultrasonic detectors translate ultrasonic emissions…into sounds the
human ear can hear."
Loken claims that technicians who use ultrasonic detectors on a daily basis
can achieve accuracy that exceeds 98%. And regarding frequency of
inspections, he recommends that process components of equipment as well
as drip, main steam traps should be checked twice a year. He suggests that
heating steam traps (in facilities that use steam for space heating) should be
tested annually. He also stresses the importance of instituting a reporting
system to keep tabs on the location, type, size, capacity, and condition of all
traps in a steam system.
47
Creating A Maintenance Program
Why go through the hard work of setting up a maintenance program for
steam traps?
When valves or steam traps leak or fail, it can be extremely costly in terms of
product quality, safety and energy loss. Valve operation effects the way fluids
will flow through a system. There are great differences in the way particular
valves and steam traps work. Ultrasonic testing makes it easy to adjust for
these differences and readily determine operating conditions while valves
and traps are on-line.
48
The Microsonic Stethoscope has proven to be an extremely effective tool for
testing steam traps for proper operation. Thousands are now being used for
this purpose, and our customers have realized substantial savings in both
maintenance costs and steam generation costs by using this method.
Energy costs will certainly continue to escalate, and an effective energy
conservation program can make the difference between profit and loss.
There are several types of steam traps on the market, but all have the same
purpose, that is to remove condensed steam, air and gasses from the system
and thereby improve efficiency and protect the system from damage. Steam
pressure, temperature, and capacities determine what type of trap will be
used in a particular application. A steam trap that fails in the open position
will discharge live steam, thereby wasting energy and degrading system
performance. A steam trap that fails in the closed position will not discharge
condensate, and damage may result to system components.
There are two main types of steam traps, those that discharge condensate
intermittently, and those that discharge continuously. In the first category
are the inverted bucket design and the disk (thermodynamic) design. Float,
thermostatic and float-thermostatic designs comprise the second category.
Testing methods are essentially the same for both types, and we assume that
the proper type trap has been selected for the particular application.
The first step in testing a steam trap is to determine if it is hot or cold. Place
a hand near the trap. If the trap is cold the problem could be a plugged
strainer upstream, or the trap outlet may be plugged with dirt. In an inverted
bucket type the bucket may have come unhooked. In the float and the
thermostatic type the thermostatic element may have failed shut or the float
may be jammed or collapsed. The disc may be jammed in a disc trap. Under
any of these conditions, no sound will be heard with the ultrasonic tool.
If the trap is hot, place the probe of the tool against the trap near the
discharge side. A continuous rushing sound suggests that the trap has
malfunctioned and is discharging live steam continuously. A properly
operating inverted bucket should discharge intermittently, as should a
properly operating disc trap, which will discharge 6 to 12 times per minute.
The discharge of live steam in a float and thermostatic trap is evidenced by a
higher than normal noise level and sound pitch.
These are but a few general guidelines for testing steam traps with the
ultrasonic tools. As with any type of testing, the test instrument only
49
provides evidence, which must be evaluated by the user. As the users
experience increases, so will the effectiveness of any testing program.
Valves
ULTRASONIC INSPECTION OF VALVES
Leak Detection Method
50
SECTION 8
Of
51
STEAM TRAPS
PREFACE
52
STEAM TRAPS
Process Traps
53
STEAM TRAPS
Drip Trap
54
STEAM TRAPS
Where are they?
Trace Traps
55
STEAM TRAPS
INVERTED BUCKET TRAP (A)
x The maximum pressure rating on the bucket trap should be shown on the
metal tag located on the trap.
x The size of the "hole" in the condensate discharge seat, along with the
steam pressure, determines the trap's capacity to discharge condensate.
Lower pressure steam traps have larger condensate discharge "holes"
than higher pressure rated steam traps.
56
STEAM TRAPS
INVERTED BUCKET TRAP (B)
57
STEAM TRAPS
INVERTED BUCKET TRAP (C)
DETAILED I.B. TRAP OPERATION
58
STEAM TRAPS
INVERTED BUCKET TRAP (D)
Bucket up.
Valve is closed on seat.
59
STEAM TRAPS
INVERTED BUCKET TRAP (E)
NOTE: Background noise level = "0"
60
STEAM TRAPS
THERMODYNAMIC TRAP (A)
61
STEAM TRAPS
BASIC THERMODYNAMIC TRAP
62
STEAM TRAPS
THERMODYNAMIC TRAP ©
63
STEAM TRAPS
64
STEAM TRAPS
FREE FLOAT TRAP (A)
65
STEAM TRAPS
FLOAT & TRAP OPERATION (B)
BASIC F&T TRAP OPERATION - NORMAL LOAD
NOTE: Background Noise Level = "0"
67
STEAM TRAPS
THERMOSTTIC TRAP (A)
68
STEAM TRAPS
THERMOSTATIC TRAP (B)
THERMOSTATIC TRAPS
THERMOSTATIC TRAP:
Cold condensate during startup
drains through the trap. As
temperatures reach 10 to 30
degrees Fahrenheit of
saturation, the trap closes.
During operation thermostatic
traps find an equilibrium point
to drain condensate which is
approximately 10 to 30 degrees
below saturation at a
continuous flow.
69
STEAM TRAPS
THERMOSTATIC TRAP OPERATION (C)
BASIC THERMOSTATIC TRAP OPERATION - NORMAL LOAD
CLOSED - NO DISCHARGE
70
SECTION 9 - STEAM COST CHARTS
COST OF LOST STEAM
Orifice 100 psi 125 psi 150 psi 200 psi 250 psi 300 psi
Diameter
1/32" 2.7 3.3 3.9 531 6.3 7.4
1/16" 10.8 13.2 15.6 20.3 25.1 29.8
3/32" 24.4 29.7 35.1 45.7 56.4 67.0
1/8" 43.4 52.9 62.4 81.3 100 119
5/32" 67.9 82.7 97.4 127 156 186
3/1" 97.7 119 140 183 226 268
7/32" 133 162 191 249 307 365
1/4" 173 212 250 325 401 477
9/32" 220 268 316 412 507 603
5/16" 272 331 390 508 327 745
11/32" 329 400 472 615 758 901
3/8" 391 476 561 732 902 1073
13/32" 459 559 659 859 1059 1259
7/16" 532 648 764 996 1228 1460
15/32" 611 744 877 1144 1410 1676
1/2" 695 847 998 1301 1604 1907
71
FAILED STEAM TRAP DOLLAR LOSS TABLE FOR RADIATOR TRAPS
Steam Cost @ $6.00/1000 lbs.
Pressure balanced thermostatic radiator traps are most commonly found on low
pressure (25 psig and under) steam heating systems. Located on radiators, convectors
and other radiant heat units, there may be literally hundreds of these scattered
throughout larger facilities. The operating unit within the trap, a pressure-balanced
disc or bellows, is filled with a distilled liquid to respond to the changes in temperature
(i.e. pressure) within the trap. The disc or bellows will generally "fail open" after three
to five years of hard work (after five years it has opened and closed hundreds of
thousands of times). The orifice sizes (*) shown, for all the steam traps, are
conservative estimates of the average size found in these traps. Actual dollar loss may
be more or less than shown.
NOTE:
THE DOLLAR COST FIGURES SHOWN
ON ALL THESE CHARTS REFLECTS
THE COST OF STEAM IN THE 1980’S.
72
DOLLAR LOSS TABLE FOR FLOAT AND THERMOSTATIC TRAPS
Steam cost @ $6.00/1000 lbs.
Float & Thermostatic (F&T) traps are found where higher levels of condensate are
produced (Unit heaters, end-of-mains, heat exchangers, etc.) The modulating control
provided by the float allows for continuous discharge of condensate when necessary.
The air vent in this trap will generally "fail open" after three to five years of hard
work. The mechanism and float assembly, which allows the condensate to discharge,
may operate efficiently for eight to ten years, and will normally "fail closed" after this
time. However, sludge and debris accumulation may cause the assembly to fail open
and waste "big bucks" as shown. Actual dollar loss may be more or less than shown.
73
DOLLAR LOSS TABLE FOR INVERTED BUCKET TRAPS
Steam Cost @ $6/1000
Pressure @ Trap 75 psig 100 psig 125 psig 150 psig 200 psig 250 psig
* Assigned orifice sizes employed in the traps below when
PIPE SIZE under the differential steam pressure shown.
1/2" *1/8" *1/8" *1/8" *7/64" *7/64" *3/32"
Dollar $37 $47 $57 $53 $68 $72
Loss/Month
3/4" *5/32" *5/32" *5/32" *1/8" *1/8" *7/64"
Dollar $57 $73 $89 $67 $87 $84
Loss/Month
1" *9/32" *1/4" *1/4" *7/32" *3/16" *3/16"
Dollar $185 $187 $229 $206 $197 $244
Loss/Month
74
75
SECTION 10 - BENEFITS
The estimated cost per year of on 1/8" air leak is $2,980.00. * If only one 1/8"
air leak was assumed for each of the main plant areas, the total annual loss
cost would be approximately $23,840.00. * Nitrogen leaks are even more
expensive events. One Nitrogen leak of only 1/16" costs a whopping
$10,700.00 (est.)** per annum. If we use the air leak scenario for the 1/16"
Nitrogen leak, the loss cost would be almost $75,000.00. A larger tank such
as a broken 1/4" OD instrument line will cost a plant $270.00 per day. THAT'S
OVER $90,000.00 per year in Nitrogen for ONE leak.
76
PAY BACK ANALYSIS
STEAM LEAKS
In a steam system with 150 lbs. of pressure and a production cost of $6 per
thousand pounds, a leak 1/32" in diameter - no larger than the tip of a ball
point pen - can cost $249 per year.
At Sun Co.'s Toledo, Ohio refinery, the ultrasonic testing identified 188
malfunctioning steam traps. Savings from replacing these traps have been in
the range of $56,000 per year based on reducing 450 p.s.i. steam
consumption by about 1,000 lb./hr.
Chevron USA, Perth Amboy NJ has six to eight thousand steam traps
throughout the plant. The plant generates close to 500,000 lb./hr. of steam. A
steam trap audit revealed the trap failure rate was up to 28%. The refinery has
increased its steam trap reliability by 15% within two years after ultrasonic
testing was put into use. The reduction in steam losses is savings at least
$50,000 a month.
AIR LEAKS
N-Ren . . . A bearing on one of their two 500 H.P. motors froze up and did
$2,500 damage. Using the stethoscope module, they picked up a bad bearing
noise on the second motor . . . resulting in immediate repair and avoiding a
complete shutdown in one area of the plant.
78
What causes air leaks?
Air cylinders often leak around the rod seals or piston packing. Piston-
packing leaks are apparent at the cylinder control valve exhaust port.
Pipefittings may be loose because equipment has been improperly installed
or because sealant was improperly applied during installation.
Poor quality materials also can be a cause. In other instances, the location of
the piping causes a leak. If a pipe connection is bumped occasionally by lift
trucks, pallet jacks, or other material handling equipment, the fittings may
become cracked.
Sometimes leaks are the result of human error. Workers may leave leaking
tools on, often beyond the inlet air isolation valves, or neglect to close valves
and halt the supply of air when there is no need for a particular application or
when production is shut down.
The audit
Any manufacturing plant will benefit from a compressed air system audit.
Typically, production demands account for only 50 percent of the total
demand for compressed air the remainder is lost. An audit pinpoints all air
leaks.
The audit concludes with a report listing operating costs, the cost of
improvements, projected savings, and a plan to achieve successful results.
In one plant repairing 324 air leaks lowered the demand for air an average of
750 cfm on the first shift, 475 cfm on the second shift, and 425 cfm on the
third shift and Saturdays. The air leaks cost $52,304/year.
80
Air-leak inspections can be conducted with the equipment on or off. As a
rule, technicians begin by determining at what kinds of loads the air
compressors are operating. They use the ultrasonic tools to establish sound
patterns of properly operating equipment. It is important to slowly scan the
entire air line system.
The technician aims the ultrasonic detector directly at the part of the machine
under inspection and makes small cross-pattern movements along all
exposed sections. The more sensitivity levels the instrument has, the better
it performs. If, for example, a one inch. pipe is suspected of leaking, the
technician should wave the gun an inch or two in each direction, moving
parallel to the pipe until finding the leak. Then the instrument's close focus
adapter can be honed in on the exact location of the leak. The problem may
actually be in the fitting.
When testing for leaks in air or blow-off applications near open air tubes, for
example, the technicians must focus the tool away from interfering noise and
isolate the ultrasonic sounds.
Every leak should be tagged with the location and an identification number.
A note should also record a description of each leak, including the size. The
make and serial number of equipment such as quick couplers, filters,
regulators, and lubricators that may be causing a chronic leakage problem
should be recorded so as to avoid purchasing the part again.
The technician should double-check each leak that is repaired before moving
on to the next area. Often new leaks are inadvertently created during the
repair stage and go unnoticed because the part is not retested. Using
confirmation and shielding techniques, such as sealing, always pays off
when the entire connection is checked one final time.
After the equipment has been repaired, the tag is removed, but the recording
sheet should be kept for reference. Finally, the technician should monitor the
load of the air compressors are too large for its real air demands. Many
compressors are designed to operate most efficiently at or near full load. If a
81
compressor is consuming 80 percent of the input power to deliver 50 percent
of its capacity following repairs, the plant might be wise to consider smaller
air compressors. The savings can be substantial.
After the number of air leaks has been determined and repairs have been
made, it is important to document the program, including an estimate of
projected cost savings. The costs of labor, materials, cooling water, and
other related expenses must be factored in.
Costs based on 75 psi Syst. at a production cost of $0.14/MCF, with a run time of 8,760
Hours/Year
82
83
SPEECH GIVEN AT MEETING OF NON DESTRUCTIVE TESTING
SOCIETY
As the name Ultrasonic implies, this term deals with that branch of acoustics
whose frequency waves are above the highest frequency audible to the
human ear. Ultrasonic vibrations (Sound Waves) are measured in terms of
Hertz (Hz). One Hz is one wave cycle per second. The human ear is generally
assumed to hear sounds with a frequency of 16 Hertz up to a limit of 20 Kilo-
Hertz (20,000 cycles per second). However, most sounds, which we hear, are
in a very limited range, considerably below this theoretical limit.
As the frequency of the sound wave changes, the way in which the sound
wave propagates also changes. Low frequency sounds tend to propagate
spherically with equal intensity in every direction. Higher frequency waves
particularly those over 20 kilohertz tend to propagate more directionally like a
beam. This makes the location easier to pinpoint. As the wave frequency
increases it becomes more and more attenuated by distance, requiring the
detector to be closer to the source or more sensitive to hear the vibration.
Like other forms of nondestructive testing, leak testing has a great impact on
the safety or performance of a product. Reliable leak testing saves costs by
reducing the number of reworked products, warranty repairs and liability
claims. The time and money invested in leak testing often produces
immediate profit.
2. CONTAMINATION
With stricter OSHA and environmental regulations, this reason for testing is
growing rapidly. Leakage of dangerous gases or liquids pollutes and creates
serious personnel hazards.
3. RELIABILITY
Component reliability has long been a major reason for leakage testing. Leak
tests operate directly to assure serviceability of critical parts from
pacemakers to refrigeration units.
Turbulent Flow:
Sometimes called sonic or choked flow, turbulent flow is the most widely
recognized source of ultrasonic vibrations. Turbulent flow occurs with any
fluid whether a liquid or a gas. This type of flow is one of the three basic flow
modes. Laminar and molecular are the other two. Of the three, however, only
the turbulent flow of a fluid across a pressure boundary creates acoustic
waves. These waves can be transmitted through the medium of the fluid
itself, through the containment structure, or through the air surrounding the
containment structure. Thus, depending upon the situation, turbulent flow
can be detected in a variety of ways. Turbulent flow often occurs through
holes with a diameter of .015 inches to .0005 inches. It is generally assumed
that the smallest detectable flow through leaks this size is 1 x 10-2 standard
cc/sec. (a rate equivalent to a pound of Freon leaking out of a container every
3 months). Besides instrument sensitivity two other controllable factors,
viscosity and velocity can improve test results. Lower viscosity fluids tend to
create greater turbulent energy and as a result, pressurization with a gas like
helium may allow the location of leaks, which could not be found with air. In
85
the same way, great velocity (or its complement, a greater pressure
differential) causes increased turbulent energy. For practical purposes
pressure differentials of 5 psi are at the lower limit of delectability but with
small holes in rigid material leaks with a pressure as small as one-half pound
pressure have been successfully detected. Higher pressures can cause the
acoustic waves to have a higher and more constant amplitude, making leak
testing easier and more reliable.
Liquid Movement:
Besides turbulent flow, liquid movements such as cavitation, flashing of a
liquid to a vapor, and bubble bursts can also produce high-energy ultrasonic
noise. Cavitation can be especially useful for finding small vacuum leaks,
which are usually considered difficult to find ultrasonically. By applying a
high surface tension liquid, (such as alcohol) on the area to be tested, the
ultrasonic energy produced as the film is broken by the vacuum, creates a
signal which is detectable at a distance of several feet. In the same way, small
bubbles from synthetic bubble fluids applied across a pressure boundary
create strong ultrasonic signals as they burst and reform. Bubbles, which are
often too small to be seen, can be heard easily ultrasonically. Soap and water
will not work for this technique. Soap or detergent solutions form a great
number of bubbles when applied. This makes it difficult to distinguish real
from apparent leaks. In addition, soap solutions form large rather than small
bubbles and as a result, they do not produce much ultrasonic energy nor do
they burst very often. For these and a number of other reasons soap or
detergent solutions have been banned by a number of regulatory agencies
such as ASTM and ASME for any leak detection use.
Mechanical Movement:
Another widely used source of ultrasonic energy results from contact
between metal parts and stress. Stressed material, which results in
stretching, shearing, abrading or other types of deformation releases high
levels of ultrasonic energy. Ultrasonic sound resulting from friction is often
used to monitor machines to prevent shutdowns and predict maintenance
needs. Examples of problems that are easy to detect are: Bearings with pits,
cracked races, loose parts, lubrication failure, misalignment, malfunctioning
valves or gears. By detecting defects such as insufficient oil film, worn
86
bearings, misalignment, or defective gears before significant increases in
vibration or temperature incipient failures can be prevented.
Sound Generation:
A technique for testing unpressurized containers involves the use of an
ultrasonic sound generator and a detector matched to the same frequency.
When used in a closed container with walls, which reflect rather than dampen
noise, the ultrasonic signals will pass through small leaks and can be
detected. This technique has been used successfully on items such as:
welded seams, airplane compartments, refrigerators, automobile windows,
condenser tubes and large tanks.
Electrical Discharge:
The fourth type of ultrasonic noise that can be detected is generated by
electrical discharges (corona), sparks, and flashovers. When an electrical
spark jumps from one object to another, the heated air expands rapidly and
produces an airborne shock wave. (This effect is similar to that of "thunder"
which accompanies a lightning stroke). The strong agitation of the air
produces ultrasonic noise. Therefore, the detection device can be used to
locate electrical defects, i.e., high-voltage corona discharges, arcs in cables,
on trolley arms, carbon brushes, transformers, motors, contactors,
insulators, reactors, distribution systems and other electrical installations
subject to electrical leakage or breakdown of insulation.
87
SECTION 11
FEATURES AND PRICE COMPARISON
OF COMPETITIVE EQUIPMENT
88
SECTION 12
89
INDUSTRIAL & COMMERCIAL
ULTRASONIC INSPECTION
DESCRIPTION
Inspection of mechanical equipment with EFI ultrasonic detection equipment has many advantages.
Ultrasound inspection provides early warning of bearing failure, detects lack of lubrication, detects leaks in
compressed-air and vacuum systems, prevents over lubrication and can be used on high as well as low
speed bearings. In addition, since ultrasound is a high frequency, short wave signal, it is possible to filter
out stray, confusing background noises and focuses on the specific item to be inspected. Basic inspection
methods are extremely simple and require very little training. In addition, ultrasonic testing works
extremely well with vibration technology. In fact the two technologies complement each other and enhance
any PDM, (Predictive Maintenance) program.
Some common areas for ultrasonic inspection in the industrial & commercial environment:
Detection Methods
Pressurized air & gas leaks produce turbulence with high frequency components. To locate compressed air
and gas leaks, simply scan the test area with the hand held EFI Microsonic detector. If a leak is present,
ultrasonic sound not audible to the human ear is produced. This high frequency sound will be "heard" by
the EFI detector and converted into an audible "hissing" sound heard through the systems headphones.
Simply follow it to the loudest point. If it is difficult to discriminate the leaks location, reduce the
sensitivity and continue to follow to the loudest point.
90
BEARINGS, PUMPS & MOTORS
ULTRASONIC INSPECTION
DESCRIPTION
Inspection of mechanical equipment with ultrasonic instruments such as the Microsonic unit has many
advantages. Ultrasound inspection provides:
In addition, since ultrasound is a high frequency, short wave signal, it is possible to filter out stray,
confusing background noises and focuses on the specific item to be inspected. Basic inspection methods are
extremely simple and require very little training. In addition ultrasonic testing works extremely well with
vibration technology. In fact the two technologies complement each other and enhance any PDM,
(Predictive Maintenance) program.
There are two basic methods for ultrasonic bearing monitoring: comparative and historical. In order to
trouble shoot bearings or to establish a baseline, it is necessary to compare similar bearings for potential
differences in amplitude and sound quality. To do this, make a reference point on a bearing housing or use
the grease fitting, using the stethoscope module make contact with the machinery and reduce the sensitivity
until the bearing reads 20 on the meter. Then compare this base reading to other similar bearings. A failing
bearing will show an 8 dB gain. Once a series of bearings have been tested, and a base line set, data is
recorded and then compared to future readings for historical trending and analysis.
91
COMPRESSORS, PRESSURE & VACUUM
SYSTEM ULTRASONIC INSPECTION
DESCRIPTION
Compressors are the heart of any compressed gas system. Routine inspection and maintenance can prevent
unplanned downtime. Although any type of compressor can be inspected ultrasonically, the most common
application centers on larger reciprocating types. Specifically, valve function in these compressors is
critical. Minor valve leaks can rapidly lead to large leaks, which can effect production and impact on plant
safety.
As with any mechanical movement, there is a "normal" operation and a "deviation". In the case of valves,
normal function is the typical open/close movement. Ultrasonically this will be observed as a rhythmic
movement. When valve movement changes due to leakage or sticking, the sound pattern changes. Each
condition has ultrasonic components that can be sensed and monitored by the Microsonic detection unit.
Due to the short wave, high frequency nature of ultrasound, the sounds produced by a compressor valve can
be isolated, which provides a clear test result.
Detection Method
For the "contact' method touch the valve with the contact probe and reduce the sensitivity until it is
possible to obtain a meter swing around mid-line and hear the valve open/close movement. When testing,
be sure to compare similar valves to each other (i.e. intake to intake, exhaust to exhaust) and under the
same conditions (i.e. idling vs. working). For additional localization, use the scanning module with rubber
focusing extension.
Compressed air and gas (Oxy, Nitrogen, LNG, CNG, etc) and vacuum systems are easily checked for leaks
or system flow. Fittings, valves, couplings, regulators, hoses, piping, auto-bleeders, pneumatic actuators,
gaskets & seals, etc are among the system components easily checked. Ultrasound is produced by the
passage of air or gas though an orifice under pressure or vacuum. The ultrasonic signature is “heard” by our
detectors and converted into a sound you can hear through headphones and seen as an indication on an
analog meter.
Detection method
Simply scan detector along system components (pipe, valves, connectors, etc) until leak is found.
Ordinary sounds such as background noise, talking or machinery (no matter how loud) are not detected.
But leaks are easily pinpointed even in otherwise deafening background sound levels.
DESCRIPTION
When valves or steam traps leak or fail, it can be extremely costly in terms of product quality, safety and
energy loss. Valve operation affects the way fluids will flow through a system. There are great differences
in the way particular valves and steam traps work. Ultrasonic testing makes it easy to adjust for these
differences and readily determine operating conditions while valves and traps are on-line.
As fluid moves from the high-pressure side of a valve through the seat to the low-pressure side, it produces
turbulence. This turbulence generates ultrasound, which is detected by the ultrasonic probe, and translated,
via heterodyning, down into the audible range. The translated ultrasounds are heard through headphones
and seen as intensity increments on a meter. High frequency tuning allows users to adjust for differences in
fluid viscosity (i.e. water vs. steam) and reduce any interference from stray pipe noises.
Inspection methods vary depending on the type of valve or steam trap. Therefore the primary rule is to
know the details of your system, for example the way a specific trap or valve may work under specific
conditions. In order to determine leakage or blockage: touch upstream of the valve or trap and reduce the
sensitivity of the instrument until the meter reads about 50. If it is desirable to hear the specific sound
quality of the fluid, simply tune the frequency until the sound you would expect to hear becomes clear. It's
that simple. Next, touch downstream of the valve or trap and compare intensity levels. If the sound is
louder down stream, the fluid is passing through. If the sound level is low, the valve or trap is closed.
Ultrasonic valve and steam trap inspection is considered a "positive" test in that an operator can instantly
identify sound quality and intensity differentials and thereby determine operating condition accurately.
93
PIPE, JOINTS, VAULTS, VALVES, & TANKS
ULTRASONIC INSPECTION
DESCRIPTION
Pipe is the heart of any gas or liquid distribution system. Inspection and maintenance can prevent
unplanned leaks and downtime. Any type of pipe can be inspected ultrasonically.
x Concrete
x PVC, PE
x Steel
x Iron
x Aluminum
x Copper
x Fiberglass Filament Wound, Etc.
Ultrasonic testing is done during assembly, WITHOUT WATER OR AIR PRESSURE, BEFORE
BURYING PIPE! Find Rolled or Pinched Gaskets, Cracks or Pinholes. Frequently this equipment pays for
itself with the first use! You may also use the EFI Microsonic tool to detect leaks underground after the
project is buried.
DETECTION METHODS
During assembly, a Microsonic tone generator is placed inside the pipe or other volume (Vault, Manhole,
etc,) this will saturate the inside area with high intensity ultrasonic sound, not audible to the human ear.
This high intensity ultrasonic sound will find and exit any hole in the pipe or joint. A hand held Microsonic
Detector is then used to scan the area being tested for leaks (seals, gaskets, cracks or pinholes). When a
leak is detected the operator will hear an audible indication in his headphones and will see an indication on
the analog meter built into the detector. It's that simple, Ultrasonic testing is quick, accurate and cost
effective.
Pressurized air & gas leaks produce turbulence with high frequency components. To locate compressed air
and gas leaks, simply scan the test area with the hand held EFI Microsonic detector. If a leak is present,
ultrasonic sound not audible to the human ear is produced. This high frequency sound will be "heard" by
the EFI detector and converted into an audible "hissing" sound heard through the systems headphones.
Simply follow it to the loudest point. If it is difficult to discriminate the leaks location, reduce the
sensitivity and continue to follow to the loudest point.
94
TRANSPORTATION & EQUIPMENT
ULTRASONIC INSPECTION
DESCRIPTION
The most common areas for ultrasonic inspection in the transportation industry are: wind noise, water
leaks, air brakes, and emission systems. Until the advent of ultrasound, water leak and wind noise detection
involved many hours of trial and error with a water hose and flashlight. Often a few trips around the block,
listening with a doctor's stethoscope for a wind noise captured two people for many hours. Air brake leaks
and emission leaks can take hours to locate using conventional soap and water bubble testing. Not only can
service shops benefit from Ultrasonic Inspection, so can Quality Assurance departments by providing
accurate fast and simple testing.
95
MARINE
ULTRASONIC INSPECTION
DESCRIPTION
Ultrasonic inspection can be used in practically every phase of the maritime industry. There are application
for marine vessels, dry docks, ship repair and shipbuilding. Some of the major areas of inspection cover
water tightness integrity of bulkheads, leak detection of hatches and vapor recovery systems, condensers,
steam systems, pressurized gas systems (including nitrogen blankets), valve leak detection/blockage and
steam traps. Mechanical applications include early warning of bearing failure, inspection of motors, pumps,
gears, gearboxes and compressors. Dry dock usage not only includes all of the above, but also extremely
large energy savings through compressed air leak detection.
High frequency sounds are produced by operating equipment and fluid flows. The Microsonic unit detects
subtle changes in mechanical equipment and turbulence produced by leakage to provide early warning.
Ultrasounds are translated into the audible range where the sound quality is easily recognized through
acoustically isolating headphones. The headphones are designed to be used in the extremely noisy
environment of the engine room. Intensity levels are read on a meter for trending, diagnosis and trouble
shooting purposes. A patented Tone Generator can be used to test for leaks in lieu of pressure by flooding
an area with intense ultrasound. The sound will deflect off a solid surface and penetrate leak sites.
Detection Methods
To locate leaks around pressure or vacuum systems simply scan the area while listening for a "hissing"
sound and follow it to the loudest point. Vapor recovery systems can be checked on-line in this manner.
Hatches and bulkheads may be tested with the patented ultrasonic Tone Generator. Place the generator on
one side (i.e. of the bulkhead) and scan the other side for sonic penetration, which will have a distinctive
tone sound. Scan the area to the loudest point of emission, which will indicate the leak site. For valves,
touch upstream and reduce the sensitivity to get a mid-line reading on the meter, then touch downstream
and compare intensity levels. A more intense reading downstream indicates leakage. No sound indicates
blockage. Set a baseline by selecting one test/reference point, touch that point with the contact probe, and
reduce the sensitivity to obtain a mid meter reading. An increase of 8 dB indicates "pre-failure" or lack of
lubrication, while an increase of 12-16 dB over baseline indicates the beginning of the failure mode. It's
that simple.
96
AIRCRAFT
ULTRASONIC INSPECTIONS
DESCRIPTION
Aircraft have many systems that can be checked ultrasonically. Some of the more common applications
include:
Operating systems such as compressed gas systems, valves, motors, pumps, etc., all produce ultrasound.
Some high frequency sounds are generated from turbulence, others from friction. As components begin to
wear, fail or leak, there is a change in the normal ultrasonic pattern. This can be detected as an increase in
amplitude, a change in sound quality or a change in sound pattern. Since ultrasound is a high frequency,
short wave signal, it will isolate the signal by localizing the problems and detect subtle changes for early
warning detection.
The Microsonic test unit detects minute changes in ultrasound and converts these signals so that they may
be heard through headphones, and observed as intensity increments on a meter. By using plug-in modules
for either a scanning mode or a contact mode, equipment may be inspected for leakage or for mechanical
problems. Due to its portability and its' rating of Intrinsically Safe, class 1, Division 1, Groups A, B, C, &
D, the Microsonic unit may be used all around the aircraft.
Detection Methods
For general leak detection, in a scanning mode, move along the area to be tested with the sensitivity at high
and, using a slight waving motion, listen for the loudest "hissing" sound and follow the sound to the loudest
point. Use the patented Tone Generator to test for cabin pressure and cockpit window leaks in the same
manner. The only difference will be the sound, which is heard as a distinctive tone, with graduating
intensity. For valves and actuators, touch upstream and reduce the sensitivity to a mid-line reading.
Compare with the downstream reading. Test bearings and mechanical equipment by reducing the
sensitivity first and then tune the frequency until the desired mechanical sound is heard. Compare readings
over time for trending. It's that simple.
97
REMEMBER, TO FIX IT…..FIRST YOU
HAVE TO FIND AMUSEMENT RIDE INDUSTRY IT!
ULTRASONIC INSPECTION
DESCRIPTION
Inspection of mechanical equipment with EFI ultrasonic detection equipment has many advantages.
Ultrasound inspection provides early warning of bearing failure, detects lack of lubrication, detects leaks in
compressed-air and vacuum systems, prevents over lubrication and can be used on high as well as low
speed bearings. In addition, since ultrasound is a high frequency, short wave signal, it is possible to filter
out stray, confusing background noises and focuses on the specific item to be inspected. Basic inspection
methods are extremely simple and require very little training. In addition, ultrasonic testing works
extremely well with vibration technology. In fact the two technologies complement each other and enhance
any PDM, (Predictive Maintenance) program.
Some common areas for ultrasonic inspection in the amusement ride industry include:
x COMPRESSED-AIR SYSTEMS FOR LEAKS
x AIR BRAKE SYSTEMS FOR LEAKS
x VACUUM SYSTEMS FOR LEAKS
x BEARINGS FOR EARLY WEAR
x ELECTRIC MOTORS FOR BEARING WEAR, BRUSH HOP, AND ELECTRICAL
SHORTING
x ELECTRIC PANELS FOR ARCING AND SHORTING
x DRIVE BELTS FOR CRACKS AND WEAR (with equipment in operation & belt guards in
place)
x PUMPS FOR INTERNAL WEAR & LEAKAGE
x HYDRAULIC SYSTEMS FOR INTERNAL LEAKAGE
x RAILS, TRACKS & SUPPORTS FOR LOOSE COMPONENTS & LEAKAGE
x FILTRATION SYSTEMS FOR FLOW
Detection Methods
Pressurized air & gas leaks produce turbulence with high frequency components. To locate compressed air
and gas leaks, simply scan the test area with the hand held EFI Microsonic detector. If a leak is present,
ultrasonic sound not audible to the human ear is produced. This high frequency sound will be "heard" by
the EFI detector and converted into an audible "hissing" sound heard through the systems headphones.
Simply follow it to the loudest point. If it is difficult to discriminate the leaks location, reduce the
sensitivity and continue to follow to the loudest point.
Leak Detection of heat exchangers, boilers and condensers most often involves inspection of
three generic areas: tubes, tube sheets and housings. The Microsonic detection unit can be used
to detect leaks three ways: pressure leaks, vacuum leaks or by utilizing a unique Tone
transmission method.
While it may be necessary to take a unit off-line to inspect for leaks, with ultrasound, it is often
possible to perform an inspection while on-line or at partial load.
During a leak, the fluid will flow from high pressure to low pressure producing a turbulent flow at
the leak site. This turbulence has strong ultrasonic components, which are sensed and translated
(via heterodyning) into the audible range where they are heard in headphones and seen as
intensity increments on a meter.
Most often leak detection is concerned with tube leaks. In heat exchangers and condensers,
there are situation where the end plates (headers) are removed or water boxes are isolated while
the unit is still on-line or at partial load. The tube sheet is scanned while listening for a distinct
"hissing" or "rushing" sound of a leak. By adjusting the sensitivity of the instrument to help
discriminate direction, move in the direction of the tube with the loudest sound. Should the unit
require off-line inspection, it is possible to use the Ultrasonic Tone transmission method. Using
ultrasonic transmitters such as the patented Tone Generators, the heat exchanger is flooded with
intense ultrasonic sound waves on the shell side and the tube sheet is scanned for a distinct tone
sound coming from the leak. As above, adjust the sensitivity to discriminate direction and follow
the sound to the loudest point, which will be the leaking tube. While under pressure or vacuum,
fittings and casings may also be checked for leakage in a similar manner.
99
ELECTRICAL
ULTRASONIC INSPECTION
DESCRIPTION
When electrical apparatus such as switch gear, transformer, insulators or pot heads and
splices fail, the results can be catastrophic. This is just as true in industrial plants as it is in
the power transmission and distribution side. Electrical discharges such as arcing, tracking
or coronas are all potential for equipment failure. In addition, the problems of RFI and TVI
impact on our valuable communication networks. All these conditions produce ultrasound
and are detected with the Microsonic detection unit.
Arcing, tracking and corona all produce some form of ionization which disturbs the air
molecules around it. The Microsonic unit detects the high frequency noise produced by this
effect and translates it, via heterodyning, down into the audible ranges. The specific sound
quality of each type of emission is heard in headphones while the intensity of the signal is
observed on a meter. Normally, electrical equipment should be silent, although some may
produce a constant 60-cycle hum or some steady mechanical noises. These should not be
confused with the erratic, sizzling frying, uneven and popping sound of an electrical
discharge.
Detection Method
Before beginning any inspection of mid or high voltage equipment, be sure to review your
plant or company's safety procedures. Essentially, as in generic leak detection, the area of
inspection is scanned using a high sensitivity level. As the discriminate direction, reduce the
sensitivity until this is possible. If it is not possible to remove covers, or plates, scan around
the seams and vent slots. Any potentially damaging discharges should be detected.
100
ULTRASONIC
DRY-PIPE FIRE SYSTEM SURVEY
Ultrasounds, by definition, are beyond the limits of normal human hearing. Using a sophisticated detector a
technician is able translate ultrasonic signals to the range of human hearing.
The theory of ultrasonic detection is relatively simple. Frequency, the number of times a sound wave cycles
from trough to crest, is expressed in cycles per second and measured in hertz. One kilohertz is 1000 cycles
per second. Human ears can generally hear noises in the range of 20 to about 20,000 Hz (20kHz). EFI
ultrasonic detectors start at approximately 20 kHz and can work upward to sound as high as 100kHz. Thus,
Technicians using the ultrasound instrument can tune to and "hear" what is going on in operating
machinery and pressurized systems. When a leak occurs, the fluid or gas passing through produces
turbulence with strong ultrasonic components. Higher-frequency sounds cannot penetrate most solids; yet
they slip through the tiniest of openings. Ultrasound detectors are ideal for isolating such leaks.
The pistol-shaped Microsonic detection unit is battery powered and lightweight. Operators can easily leak
test large sections of piping quickly and effectively. Leaks in pressurized Dry-Pipe systems are found by
simply sweeping the Microsonic detector over the area to be checked. Ultrasound generated at the leak
source is made audible in the headphones and visible on the unit's analog meter. Testing using a soap
solution and watching for bubbles is very time consuming and will frequently miss leaks altogether if the
tested area is not visible
The best plan is to inspect the entire plant department by department, always following the same pattern.
However, if such a program seems too daunting, a plant might limit periodic inspections to one or two
departments. As maintenance crews become more familiar with ultrasound and inspection techniques, the
survey can be expanded to include the entire operation.
The technician aims the ultrasonic scanner directly at the part of the system under inspection and makes
small cross-pattern movements along all exposed sections. The more sensitivity levels the instrument has,
the better it performs. If, for example, a 1 in. pipe is suspected of leaking, the technician should wave the
gun an inch or two in each direction, moving parallel to the pipe until finding the leak. Then the
instrument's close focus adapter can be honed in on the exact location of the leak. The problem may
actually be in the fitting.
Every leak should be tagged with the location and an identification number. A note should also record a
description of each leak, including the size.
The technician should double-check each leak that is repaired before moving on to the next area. Often new
leaks are inadvertently created during the repair stage and go unnoticed because the area is not retested.
Using confirmation and shielding techniques, such as sealing, always pays off when the entire connection is
checked one final time.
REMEMBER, TO FIX IT…..FIRST YOU HAVE TO FIND IT!
101
MILITARY VEHICLE GROUND SUPPORT
ULTRASONIC INSPECTION
DESCRIPTION
The most common areas for ultrasonic inspection in ground and air transportation are: air/water/gas leaks
into personnel & equipment compartments, pressurized systems leaks, air brakes, motors, pumps &
bearings. Until the advent of ultrasound, liquid and gas intrusion detection involved many hours of trial and
error with a water hose and flashlight. Often applying a liquid under pressure or listening with a
conventional stethoscope for a pressure leak, required two people for many hours. Air brake leaks, exhaust
and intake leaks can take hours to locate using conventional soap and water bubble testing. Not only can
service facilities benefit from Ultrasonic Inspection, so can Quality Assurance departments by providing
highly portable, fast, accurate, and simple testing.
Compressed gases, when leaking produce a turbulent flow with strong ultrasonic components. By scanning
fittings, a leak will be heard as a distinct "hiss". Due to the high frequency, short wave nature of ultrasound,
the sound will be loudest at its point of origin. The Microsonic unit translates the ultrasonic leak signals
into recognizable audible signals where they are heard through headphones and seen as intensity
increments on a meter. A unique test incorporates a patented ultrasonic transmitter called a Wave Form
Generator. This device is placed in a cabin, tank, container or compartment where it floods the area with an
intense ultrasonic signal. The generated ultrasound will deflect off solid seals but will flow through a leak
path.
Some of the most common areas for ultrasonic inspection include:
x COMPRESSED AIR SYSTEMS
x CNG & LNG GAS SYSTEMS
x VACUUM SYSTEMS
x INTAKE & EXHAUST SYSTEM LEAKS
x ENGINE INTERNAL DIAGNOSTICS
x DRIVE LINE DIAGNOSTICS
x BEARINGS, PUMPS, MOTORS, SERVOS
x AIR & VACUUM ACTUATORS
x COMPARTMENT SEALS & GASKETS
x HATCH, BULKHEAD, PORT, WINDOW, FLOOR & ROOF SEALS
x HYDRAULICS FUEL INJECTORS DRIVE BELTS
Detection Methods
Pressurized air, gas & fluid leaks produce turbulence with high frequency components. To locate air, gas or
fluid leaks under pressure, simply scan the test area with the hand held EFI Microsonic detector. If a leak is
present, ultrasonic sound not audible to the human ear is produced. This high frequency sound will be
"heard" by the EFI detector and converted into an audible "hissing" sound heard through the systems
headphones. Simply follow it to the loudest point. If it is difficult to discriminate the leaks location, reduce
the sensitivity and continue to follow to the loudest point.
REMEMBER, TO FIX IT…..FIRST YOU HAVE TO FIND IT!
102
COLLISION REPAIR INDUSTRY -- ULTRASONIC INSPECTION
A major repair has been completed and everything is just right, with form, fit and finish reflecting your
shops reputation for quality work!
Your customer comes in to take delivery, inspects the repairs and expects all to be to pre-accident
condition. All is well, the repairs are paid for, forms are signed, and off drives another satisfied customer!
Most of the time this is how it goes!
On occasion a vehicle comes back with a concerned or irate customer complaining about some aspect of
the repair they feel was not done properly and frequently the complaint will involve:
DOORS, DECK LID, SUN-ROOF & T-TOP (seals, weather-strips, caulking, rust)
FLOOR PAN, ROCKERS, WHEEL-HOUSE, REAR BODY PANEL (caulking, welds, rust)
WINDSHIELD, BACK-GLASS & SIDE GLASS (seals & weather-strip, Rust)
WEATHER STRIPS, CAULKING & DRIP-CHECK
Until the advent of ultrasonic testing, leak detection could involve hours of trial and error
with the use of water testing, bubble testing, tracing fluids or compressed air and powder,
often requiring two technicians for hours. Frequently the results of these efforts were less
than satisfactory!
Ultrasonic testing is fast, simple and accurate. Saving time, money and resources, while
insuring customer satisfaction.
103
NEW CAR & TRUCK DEALERSHIP ¾ SERVICE DEPARTMENT
¾ BODY SHOP
¾ FACILITY MAINTENANCE
SERVICE DEPARTMENT
Ultrasonic testing as a quality control procedure during repair and as quality assurance during a
pre-delivery inspection can have a significant affect on customer satisfaction. Ultrasonic testing when
shown to customers will also promote customer confidence and shop credibility.
BODY SHOP
x AIR & WATER LEAKS AT DOORS, DECK-LID, SUN-ROOF, REMOVABLE ROOF PANELS
x AIR & WATER LEAKS AT WINDSHIELD, BACK-GLASS, SIDE GLASS
x AIR & WATER LEAKS AT SEALS, CAULKING, WELDS, RUSTED PANELS
x LOCATE SQUEAKS & RATTLES
x LOCATE EXHAUST SYSTEM LEAKS AND RATTLES
x DETECT DAMAGED ENGINE BELTS
x DETECT DAMAGED BEARINGS
FACILITY MAINTENANCE
x LEAK TEST SHOP COMPRESSED AIR SYSTEM (MAJOR SAVINGS POTENTIAL)
o SEE ATTACHED CHART INDICATING COSTS OF COMPRESSED AIR LEAKS
x LEAK TEST FACILITY DRY-PIPE FIRE SUPPRESANT SYSTEM
x LEAK TEST DOORS, WINDOWS, STORAGE AREAS
Until the advent of ultrasonic testing, leak detection could involve hours of trial and error with the
use of water testing, bubble testing, tracing fluids or compressed air and powder, often requiring two
technicians for hours. Frequently the results of these efforts were less than satisfactory!
Ultrasonic testing is fast, simple and accurate. Saving time, money and resources,
while insuring customer satisfaction.
104
SECTION 13
http://www.oit.doe.gov/bestpractices/compressed_air/ Government
compressed air resource site (VERY GOOD)
http://enerchecksystems.com/index.html
Complete ultrasonic Dist./Mfg. (good how to site)
http://www.amgas.com/ldpage.htm
American gas & chemical Co. Ltd. Leak detection technology
http://leakzone.com
Large leak detection resource site
http://steamlink.com/1wdm.html
Steam trap resource site
http://uesystems.com/
Competing ultrasonic equipment Mfg. (good resource for applications, how to
information.)
http://www.maintenanceresources.com/referenceLibrary/ezine/ultrasonic.htm
Ultrasonic testing procedures for steam traps
http://knowpressure.org/
The Compressed Air Challenge is a voluntary collaboration of industrial users;
manufacturers, distributors, and their associations; consultants; state research
and development agencies; energy efficiency organizations and utilities.
http://www.e4i.com
Web site for Electronics For Industry, Inc.
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SECTION 14
106
The End
www.e4i.com
Thank You
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