IOM-JET-0209

Ejector
Installation, Operation, Maintenance and Manual

Graham Corporation ● 20 Florence Avenue ● Batavia, New York 14020

Email: equipment@graham-mfg.com ● www.graham.mfg.com
Phone: 585-343-2216 ● Fax: 585-343-1097
Graham Corporation

TABLE OF CONTENTS

SECTION I - GENERAL INFORMATION .....................................................3

1.1 Introduction ................................................................................................3
1.2 Principle of Operation ...............................................................................3
1.3 Mechanical Description .............................................................................3
SECTION II - INSTALLATION .......................................................................4
2.1 Initial Inspection.........................................................................................4
2.2 Installation ..................................................................................................4
SECTION III - OPERATION ............................................................................5
3.1 Startup .........................................................................................................5
3.2 Shutdown.....................................................................................................6
3.3 Switching Ejector Elements.......................................................................7
SECTION IV - TROUBLESHOOTING ...........................................................7
4.1 General ........................................................................................................7
4.2 Motive Fluid Conditions ............................................................................8
4.3 Overloading Conditions.............................................................................9
4.4 Discharge Conditions ...............................................................................10
4.5 Mechanical Damage and Wear ...............................................................10
SECTION V - OPERATOR’S MAINTENANCE ..........................................11
SECTION VI - REPAIR AND REPLACEMENT ORDERS........................11
FIGURE I ........................................................................................................ 12
FIGURE II ................................................................................................... 13
FIGURE III ........................................................................................................14
FIGURE IV ........................................................................................................15
FIGURE V .........................................................................................................15
FIGURE VI.........................................................................................................15

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Graham Corporation

SECTION I - GENERAL INFORMATION

1.1 Introduction

The purpose of an ejector is to transport a gas, liquid, powder or solid particles from
one pressure level to a higher pressure level. It is easy to operate, durable and
generally trouble-free because there are no moving parts.

It is to be emphasized that the ejector is probably one of the most foolproof, trouble-
free pieces of apparatus that operates in any vacuum cycle. This does not mean that
the apparatus can be abused beyond all limitations, nor does it mean that it can be
ignored so far as inspection, maintenance and repair are concerned.

There are a few, rather simple, rules to follow in the operation and maintenance of
ejector equipment and, if the operator will adhere to these rules, little or no difficulty
may be expected.

1.2 Principle of Operation

Atmospheric to high pressure motive fluid passes through the motive nozzle where its
pressure is dissipated in accelerating this fluid to high velocity as it exits the mouth of
the nozzle. This high velocity stream of fluid issued from the nozzle mouth entrains
the suction fluid. Entrainment between the motive fluid and the low pressure suction
fluid causes the latter to move with the motive fluid. These two streams mix as they
pass into the diffuser. The velocity profile is constantly changing and the pressure
continues to rise as the discharge of the diffuser is reached.

1.3 Mechanical Description

Refer to Page 12, Figure I for a complete description of all parts for a cast ejector and
two types of fabricated ejectors. There are only four basic parts of an ejector. They
are:

Motive nozzle (1)

Motive chest (3)
Suction chamber (5)
Inlet / outlet diffuser (7), or (7) and (9).

The motive inlet may be flanged or welded rather than NPT as shown. The suction
and discharge may have weld ends rather than flanges on fabricated ejectors only.

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SECTION II - INSTALLATION

2.1 Initial Inspection

Inspect for shipping damage to all protective covers. If damage is evident, inspect for
internal contamination and replace protective covers if the unit is going to be stored.
If the unit is damaged mechanically, notify the carrier immediately and then contact
Graham Corporation.

2.2 Installation

Sufficient clearance should be provided to permit removal of the motive chest which
contains the motive nozzle that protrudes inside the suction chamber. The ejector may
be installed in any desired position. It should be cautioned that if the ejector is
pointed vertically upward, a drain must be present in the motive chest or in the suction
piping to drain any liquid that could accumulate. This liquid will act as load until
completely flashed off, thus giving a false performance indication. The liquid could
also freeze and cause damage to the ejector.

The motive line size should correspond to the motive inlet size. Oversize lines will
reduce the motive velocity and cause condensation when the motive fluid is a
condensible. Undersized lines will result in excessive line pressure drop and, thus,
potentially low pressure motive fluid to the nozzle. If the motive fluid is a
condensible fluid (such as steam), the lines should be insulated. Refer to Page 12,
Figure I for proper piping of the motive fluid line.

The suction and discharge piping should match or be larger than that of the equipment.
A smaller size pipe will result in pressure drop, possibly causing a malfunction or
reduction in performance. A large size pipe may be required depending upon the
length of run and fittings present. Appropriate line loss calculations should be
checked. The piping should be designed so that there are no loads (forces and
moments) present that could result in damage. Flexible connections or expansion
joints should be used if there is any doubt in the load transmitted to the suction and
discharge flanges. If the discharge pipe is designed to exhaust to a hotwell, the pipe
should be submerged to a maximum of 12" below the liquid level. If the discharge
exhausts to atmosphere, the sound pressure level should be checked for meeting the
requirements of OSHA standards.

A thermostatic type trap should be avoided since they have a tendency to cause a
surge or loss of steam pressure when they initially open. This could cause the ejector
to become unstable.

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SECTION III - OPERATION

3.1 Startup

The ejector motive line should be disconnected as near as possible to the motive inlet
and the lines blown clear. This is extremely important on new installations where
weld slag and chips may be present and on units that have been idle where rust and
scale particles could exist. These particles could easily plug the motive nozzle throats.
If a strainer, separator and/or trap is present, they should be inspected and cleaned
after the lines are blown clear.

If condensers are present, check to insure that the vapor outlet of the aftercondenser
and condensate outlets are open and free of obstructions. Be sure the cooling medium
is flowing to the condenser(s). (Refer to separate manual, e.g. Shell and Tube Heat
Exchanger, Barometric Condenser, In-Line Inter/Aftercondenser or Heliflow for
proper operation.) Refer to Pages 13, 14 and 15, Figures II, III, and IV for
nomenclature for various stages and condensers.

Open all suction and discharge isolating valves if present. If the unit has dual
elements with condensers present, make sure the condenser has been designed for both
elements operating. If the condenser has been designed for one element operating,
open the suction and discharge valves to one element only (isolate other element).

Fully open the motive valve to the ‘Z’ stage(s). For optimum performance during an
evacuation cycle, the motive valves should always be open starting with the ‘Z’ stage
and proceeding to the ‘Y,’ ‘X,’ etc. stages. If a pressure gauge is present near the
motive inlet, check the reading to ensure the operating pressure is at or slightly above
that for which the unit is designed. The motive pressure gauge should be protected
with a pigtail if the motive fluid is a high temperature gas or condensible fluid. This is
to insure protection of the internal working parts of the gauge. The design operating
pressure is stamped on the ejector nameplate.

In the case of a system having twin 100% ejector elements, all four ejectors can be
operated at start-up to reduce the time required to evacuate the system. After the
system has been evacuated to the normal operating pressure, one of the ejector
elements (one Y stage and one Z stage) can be taken out of service to conserve motive
steam usage. This should be done by closing the valves in the following order:

1) ‘Y’ stage (first stage) suction.

2) ‘Y’ stage (first stage) motive inlet.
3) ‘Y’ stage (first stage) discharge.
4) ‘Z’ stage (second stage) suction.
5) ‘Z’ stage (second stage) motive inlet.
6) ‘Z’ stage (second stage) discharge (if present).

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Twin element, two stage ejectors with inter/aftercondensers are generally equipped
with relief valve(s). The relief valves are nominally set at 15 PSIG. If the operating
procedures for startup or shutdown are not followed exactly, the ejectors could be
exposed to full operating motive pressure and they are normally not designed to
withstand this pressure. The relief valves protect the ejector in the event the motive
steam is inadvertently turned on when the isolating valves are closed. The ejectors
may be designed for the motive pressure if relief valves are not present, but it is
suggested the outline drawing be checked for notes pertaining to this feature or consult
the factory.

3.2 Shutdown

There are two procedures to be considered when shutting down:

Method A: If it is desired to maintain the vacuum upstream of first stage ejector (an
isolating valve has to be present at suction) rather than allowing pressure to rise to
atmospheric pressure, the valves should be closed in the following order:

1) Close first stage suction valve.

2) Close first stage motive inlet valve.
3) Close first stage discharge valve.
4) Close second stage suction valve.
5) Close second stage motive inlet valve.
6) Close second stage discharge valve (if present).

Note: If there are more than two stages, STOP AT STEP 5 and continue to repeat
steps 3, 4 and 5 for each additional ejector present and ending with step 6 on final
stage. If the system contains an isolating valve at the first stage suction only, the
procedure would be to close this valve and then either shut off the motive to all
ejectors at once or shut them off by stages, starting at the first stage. When all motive
valves have been shut off, the cooling medium may be turned off also. If the unit is
going to be shut down for a short period of time to service the ejectors or for some
other reason, it is not necessary to shut off the cooling medium. Energy savings
should be considered when making this decision. If the unit is going to be down and
freezing of the cooling medium is possible, then measures must be taken to prevent
freezing or the unit drained as much as possible to prevent damage.

Method B: If it is not required to maintain a vacuum upstream of first stage ejector,

the valves should be closed in the following order:

1) Close main motive valve to all the ejectors or close the motive valve(s) to each
individual stage, starting at first stage and continue on to second, etc.
2) The cooling medium may be turned off as explained in preceding paragraphs.

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3.3 Switching Ejector Elements

Should it become necessary or desirable to shift from one two-stage element to

another while the unit is in operation, proceed as follows:

1) Open discharge valve of the standby second stage ejector (if provided).
2) Open second stage motive valve.
3) Open second stage suction valve. When this has been accomplished, this standby
second stage ejector begins to take suction from the intercondenser along with the
other second stage element.
4) Open first stage discharge valve on standby element.
5) Open first stage motive valve.
6) Open first stage suction valve. At this point, both two stage elements are in
parallel operation.

The operating element can now be secured by closing the valves as follows:

1) Close first stage suction valve.

2) Close first stage motive valve.
3) Close first stage discharge valve.
4) Close second stage suction valve.
5) Close second stage motive valve.
6) Close second stage discharge valve (if provided).

SECTION IV - TROUBLESHOOTING

4.1 General

Malfunctions of ejectors can be difficult to analyze unless a step-by-step procedure is

followed. Through the process of elimination, the problem area can be located and
corrected.

There are basically only four main areas that will cause an ejector to malfunction and
these are:

1) Motive fluid conditions and properties different than designed.

2) Overloading conditions.
3) Discharge conditions.
4) Mechanical damage or wear.

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4.2 Motive Fluid Conditions

With all ejectors operating, check the motive steam pressure at the steam inlet to each
stage. Do not assume the pressure measured at one will be the same at another stage
since an obstruction causing pressure drop could be present. The motive pressure
check should be performed with a calibrated gauge (make sure the gauge is protected
with a pigtail.). A pressure gauge with the appropriate scale should be installed on the
motive inlet of each stage (immediately prior to the steam chests). It is essential that
the motive pressure not be less than the design pressure at any time during operation.
Motive pressures in excess of the design pressure may also be detrimental to the
operation. If this pressure exceeds 120% of the design, a pressure reducing station
should be utilized. Normally the excessive motive pressure will waste motive fluid
and tend to choke the diffuser throat, decreasing the capacity of the ejector. Instances
of non-condensible overload, however, can be compensated for by higher than design
motive pressure. Therefore, excessive motive pressure may not always appear to be
detrimental - it may indicate a problem exists elsewhere.

The motive, if a condensible fluid, should be 100% quality or slightly superheated.

Ejectors operating at a suction pressure greater than approximately 7 mmHgA will
function on approximately 1% moisture (99% quality). Highly superheated motive
steam will act as if low steam pressure is present (due to the higher specific volume).
If there is any doubt of the quality of the steam, install a steam separator of the proper
size and type in the steam supply line as close to the ejector motive inlet as possible.
The separator serves the purpose of removing the moisture by utilizing a centrifugal
scrubbing action. The separator must be installed in a vertical position for sizes 2"
and smaller and horizontal or vertical for sizes 2-1/2" and larger. The separator
should include a bucket type trap or a blow-down valve to permit the constant
drainage of any condensate. (Note: Do not use a thermally actuated trap.) If a blow-
down valve is utilized, it is only necessary that this valve be cracked open until a
small wisp of steam is blown to atmosphere. All lines should be fully insulated for
proper operation and for personnel protection. Moisture in the motive steam can
cause erratic operation, act as load to the ejector, and result in erosion and pitting of
the steam nozzle and diffuser. The motive fluid may contain a contaminant, resulting
in a buildup in the motive nozzle as well as other parts of the ejector. In addition,
small particles can become lodged in the motive nozzle throat. The motive nozzle
may be checked for pluggage by closing the motive steam valve tightly to insure that
there is not any high pressure motive present in the motive line. Remove the
inspection/clean-out plug (if present) and with the use of a flashlight, inspect the
throat. A properly sized rod or reamer may be inserted into the opening to attempt to
dislodge or clean any material from the throat area. This same rod or reamer may be
used for checking for wear (refer to Section 4.5). The motive chest, with nozzle
intact, may be unbolted and removed for a thorough inspection.

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4.3 Overloading Conditions

Overloading can be due either to excessive process loads, air in-leakage, and/or the
load at a temperature higher than design. It must be determined if the source of the
overload is upstream of the first stage ejector or within the ejector system. This is
done by isolating the first stage ejector from the remainder of the vacuum system
upstream. A blank-off plate inserted at the suction of first stage is the easiest method.
(Note: Even if an isolating valve is present, a blank-off plate should be used since
valves may leak.)

At zero load, the ejector will evacuate to shut-off pressures of approximate values
shown below for various number of stages:

Single stage unit ------- 50 mmHgA (may be unstable)

Two stage unit---------- 4 to 10 mmHgA
Three stage unit -------- 0.8 to 1.5 mmHgA
Four stage unit --------- 0.1 to 0.2 mmHgA
Five stage unit---------- 0.01 to 0.02 mmHgA
Six stage unit ----------- 0.001 to 0.003 mmHgA

The above shut-off pressures are only approximate and will vary with each particular
ejector. However, if the blank-off test indicates the ejector is operating in a stable
condition at its approximate shut-off pressure, then it can be assumed that the ejector
most likely will operate satisfactorily along with its entire performance curve. If this
is the case, further troubleshooting would then be required on the vacuum system or
upstream of ejector.

If the shut-off pressure is not obtained or is unstable, then the troubleshooting should
be confined to the ejector system. A hydrotest for checking air leakage is
recommended, however, it should be verified that the system is designed to carry the
extra pressure and weight of the water required to fill the system. There are other
methods, such as a Halide leak detector, that are acceptable. Another method, while
the system is operating and under vacuum, is to use ordinary shaving cream applied to
all joints, etc. If a leak is present, it will suck the cream into the leaking area and is
easily observed. If there are intercondensers present in the system, overloading of the
downstream ejectors can occur due to low cooling fluid flow, high inlet cooling fluid
temperature and/or fouling. Refer to Auxiliary Operation, Maintenance & Installation
Manual for the type of condenser present.

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4.4 Discharge Conditions

Pressure exceeding the design at the discharge of any of the ejectors may be a cause of
poor performance. The last stage ejector should be checked first. If a calibrated
pressure gauge cannot be located directly at the ejector discharge, the discharge piping
should be disconnected and the ejector allowed to exhaust directly to atmosphere.

The other ejectors upstream of intercondensers should also be checked for back
pressure greater than design. The ejector must remain bolted to the condenser. An
absolute pressure gauge reading should be taken directly at discharge of ejector,
before it enters the condenser and compared to the design. If higher than design,
check for an obstruction or buildup at the inlet to the condenser or piping leading to
the condenser, buildup inside the condenser, fouled condenser, insufficient cooling
fluid or cooling fluid inlet temperature higher than design.

4.5 Mechanical Damage and Wear

The final step would be to check the internals for damage or wear. Both the motive
nozzle and diffuser throats should be checked and if the wear exceeds 7% of the
original design area, the parts should be replaced. The steam nozzle and diffuser
interior should be smooth and clean. If any scale, product build-up or roughness is
present on inlet diffuser internals, this should be removed by an acceptable method.
The tapered sections of both the nozzle and diffuser should be free of pitting, lines,
and/or ridges. CAUTION: The motive nozzles should be handled very carefully to
insure that the nozzle mouth or threads are not damaged. It is important to inspect the
motive nozzle mouth for any indentations or other irregularities. A new nozzle should
be installed if the existing one is damaged.

Visible lines on the internal section of the motive nozzle extending from throat to
mouth, even if they do not seem to be worn into the metal, usually indicate that there
is wet steam present. Motive nozzle internals may be cleaned, but nozzle replacement
is recommended. Corrective action should be taken to improve motive quality.

The threads on the motive nozzle, extension or steam chest should be checked for
wire-draw and other damage. This is a source for high pressure motive leakage to the
inside of the ejector, causing an artificial load which, in turn, increases in suction
pressure. NOTE: Steam nozzles and nozzle extensions must be securely tightened
to prevent leakage (suggested torque of 150 ft./lbs.).

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SECTION V - OPERATOR’S MAINTENANCE

First 15 and 30 Days (for new installations): Blow out steam strainers while units
are in operation.

Every 3 Months: Check steam pressure and other utilities.

Every 12 Months: Remove, clean, and inspect strainers if present. Check nozzle and
diffuser internals. Inspect relief valves, if present. NOTE: Refer to inspection points
listed in auxiliary equipment manuals such as condensers.

SECTION VI - REPAIR AND REPLACEMENT ORDERS

When it is necessary to obtain spare parts, please address your communication to:

GRAHAM CORPORATION
20 Florence Avenue
Batavia, New York 14020

Telephone: 585 / 343-2216

Spare Parts: 800 / 828-8150
Fax: 585 / 343-1097
E-MAIL: spares@graham-mfg.com
WEBSITE: http://www.graham-mfg.com

IMPORTANT - The following information should be given in order to identify the

spare parts required:

1. Serial number of unit (stamped on nameplate),

2. Name or description of part required,

3. Method of shipment (i.e. freight, express, etc.).

Graham Corporation presents the information in this manual as good engineering practice.
We cannot be held responsible for any damage to equipment that may result from mal-
operation nor for any personal injuries should they occur during normal or abnormal
operation.

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Strainer Isolating Valve Motive

3
Inlet

Motive
Inlet
Separator 2 Throat
Typical Piping
Arrangement
1 Mouth
Isolating
3 4
Valve Typical Motive
Bucket Nozzle Detail
Trap
Test
Connection Suction

Inspection/Cleanout Plug
1 5
Motive
6 Cast Ejector Inlet 3 4
8

7
2
Test
Connection
9 Suction

1 5

Discharge 6

Fabricated
May be Welded Ejector
or Bolted
Parts List
7
Part No. Description May be Cones
1 Motive Nozzle or Barstock
2 Nozzle Extension
3 Motive Chest
4 Gasket Discharge
5 Suction Chamber
6 Gasket Ejector Component Parts and
7 Inlet or Inlet/Outlet Diffuser Cross-Sectional Drawing
8 Gasket
9 Outlet Diffuser FIGURE I

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Y Stage Aftercondenser Z Stage

Y Stage Z Stage

Y - Z Condenser

Two Stage Condensing

Two Stage Condensing with Aftercondenser
Y - Z Condenser

X Stage Z Stage
Aftercondenser

Y - Z Condenser

X - Y Condenser

Three Stage Condensing

Y Stage

Z Stage
Aftercondenser

Y - Z Condenser

X - Y Condenser

Y Stage

X Stage
Three Stage Condensing with Precondenser Precondenser
FIGURE II

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Y Stage Z Stage

Y Stage

Y-Z
Z Stage Condenser
Two Stage
Single Stage Non-Condensing Two Stage Condensing
Y Stage X Stage
Z Stage Y Stage
Z Stage

Y-Z X-Y
X Stage Condenser Condenser Y-Z
Condenser
Three Stage Combined
Non-Condensing & Condensing Three Stage Condensing
X Stage Y Stage

Z Stage

X-Y
Y-Z
Condenser
Four Stage Combined Condenser
Non-Condensing & Condensing FIGURE III

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-NOTES-

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