Gas and Cylinder Characteristics
Please answer all questions in this section.
Question 1 of 77.
For any multistage compressor, if there are no interstage additions or subtractions, the MMSCFD
flow going through each stage is the same.
True
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Question 2 of 77.
Which diagram is helpful for analyzing a compressor's operation?
Pressure Volume (PV) Diagram
Rod Load Diagram
Crosshead Pin Reversal
Cylinder Temperature Diagram
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Question 3 of 77.
SCF stands for Standard Current Feet.
True False
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Question 4 of 77.
What is the correct sequence of events that occurs in each end of a cylinder during one revolution
of the crankshaft?
Suction, re-expansion, compression, discharge
Re-expansion, suction, compression, discharge
Re-expansion, compression, suction, discharge
Suction, compression, re-expansion, discharge
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Question 5 of 77.
Cylinder fixed clearance is the volume remaining when the piston is at the end of the stroke.
True False
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Question 6 of 77.
Compression ratio is calculated by dividing the discharge pressure in psig from the control panel
by the suction pressure in psig from the control panel.
True False
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Question 7 of 77.
What does PSIA mean?
Pounds per Square Inch Allowable
Pounds per Square Inch As Measured
Pounds per Square Inch Actual
Pounds per Square Inch Absolute
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Question 8 of 77.
What does "PV" as in PV Diagram mean?
Pressure Velocity
Pressure Volume
Piston Velocity
Piston Volume
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Question 9 of 77.
Utilization of a Variable Volume Clearance Pocket lowers the crank end suction volumetric
efficiency.
True False
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Question 10 of 77.
A Variable Volume Clearance Pocket (VVCP) can be adjusted while the unit is running.
True False
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Question 11 of 77.
Adjusting a Variable Volume Clearance Pocket (VVCP) below 30% volumetric efficiency could
cause premature valve failure.
True
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Question 12 of 77. Question 1 of 77.
What component must be changed when installing valve spacers?
Shorter valve retainers are used
Smaller valve cap
Removal of all steel gaskets
The valve assembly
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Question 13 of 77.
When installing high clearance valve assemblies the same retainer may be used.
True False
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Question 14 of 77.
Where would you find the correct rupture disc pressure rating and disc color for your
compressor?
Ariel Compressor Lubrication Sheet
Force feed lubrication box label
Compressor top cover label
Compressor Maintenance and Repair Manual
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Question 15 of 77.
A Lubrication Sheet can be obtained for your compressor by calling the Ariel Response Center
(ARC).
True
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Question 16 of 77.
A pressure gauge should be installed on all divider block systems because:
The pressure gauge indicates system operating pressure.
The pressure gauge is used to adjust the balance valve.
The pressure gauge can indicate lube pump failure.
The operator can not effectively troubleshoot the divider block system without a pressure gauge.
X All of the above
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Question 17 of 77.
Which force feed lubrication system component is adjusted to set the "cycle time"?
Rupture disc
Gear speed
Purge port
Lubrication pump flushing assembly
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Question 18 of 77.
The force feed cycle time is changed by adjusting the lube pump flushing assembly position.
True False
x
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Question 19 of 77.
The divider block piston cannot be removed from the bore. To fix this you must do the following:
Pump oil through the assembly until the piston moves freely.
Remove the piston with a small punch and smooth the piston with sandpaper. Clean the piston and
replace it back into the divider block.
Remove the faulty divider block and replace it with a new unit.
All of the above
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Question 20 of 77.
What can cause a rupture disc to burst?
High pressure lubrication system failure
Incorrect rupture disc installation
Installing an incorrect pressure disc
All of the above
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Question 21 of 77.
The high pressure force feed lubrication system provides lubrication to the following compressor
components. Select all that apply.
Cylinders
Connecting Rods
Crossheads
Packing Cases
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Question 22 of 77.
The Ariel Force Feed lubrication sheet displays the divider block configuration and connections.
True False
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Question 23 of 77.
The divider block assembly must cycle sequentially to continue to be operational.
True False
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Question 24 of 77.
What information do you need to provide when calling Ariel's Response Center (ARC) for technical
assistance? Choose the most correct answer.
Frame model type
Frame location and site name
Frame speed and cylinder maximum working pressures
Frame and cylinder serial numbers
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Question 25 of 77.
During a packing case rebuild; Where can you find the information that specifies which cup the
rod packing rings belong in?
Ariel Application Manual
Associated frame maintenance manual
Packing case drawing included with the rebuild kit
All of the above
Question 26 of 77.
The crosshead pin in an ELP crosshead is lubricated via passageways machined through the
crosshead.
True False
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Question 27 of 77.
What is the minimum oil temperature going into an Ariel compressor frame? _____ Degrees F.
150
180
190
170
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Question 28 of 77.
Which frame lube component is not mounted on the auxiliary end of the frame?
Oil pump
Eccentric chain tensioner cover
Oil level sight glass
Oil cooler
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Question 29 of 77.
The ELP oil circuit only effects how the main bearings are lubricated.
True False
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Question 30 of 77.
Why would oil leak around the crankshaft and down the front of the end cover?
Frame breather is plugged allowing frame to build pressure
Packing case is leaking and allowing gas to pressurize the frame
Distance piece guide vents are plugged allowing gas to leak into and pressurize the frame
All of the above
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Question 31 of 77.
Which frame lube circuit provides lubricant to the main journals via the oil gallery tube?
Traditional and ELP
High pressure system
ELP only
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Question 32 of 77.
What should the low oil pressure shutdown be set at for an Ariel compressor? ____ psig
50
45
55
35
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Question 33 of 77.
Which oil path has a rifle drilling through the connecting rod to allow oil to flow through and
lubricate the crosshead pin?
Traditional
ELP
Force Feed
Main's lube circuit
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Question 34 of 77.
Ariel does not require both a low oil pressure and a low oil level shutdown.
True False
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Question 35 of 77.
Suction and Discharge valves operate as one-way spring loaded check valves.
True False
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Question 36 of 77.
When the valve is properly installed in the cylinder, which valve has the seat facing the valve cap?
Suction valve
Discharge valve
The seat faces the valve cap for all valves
Depends on the cylinder size
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Question 37 of 77.
What types of non-metallic valve plate material used in Ariel valves. Choose all that apply.
NYX
MTX
PKX
PCX
Stainless Steel
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Question 38 of 77.
Valve spring part numbers can be selected once for an installation, regardless of changing
operating conditions.
True False
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Question 39 of 77.
A liquid test can be used to leak test compressor valves but may give incorrect results.
True False
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Question 40 of 77.
Which valve plate material is used in valves with high temperature standard applications?
PKX
MTX
NYX
PCX
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Question 41 of 77.
The valve model selection is based on cylinder design, operating pressure range, and speed
range.
True False
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Question 42 of 77.
What are the three forces that act on valve plate motion? Select the three correct answers.
Gas drag force
Spring force
Inertia force
Gas resistance force
Sticktion
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Question 43 of 77.
Some models of Ariel cylinders have interchangeable valves, care must be taken when installing
suction and discharge valves.
True False
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Question 44 of 77.
In simple terms compressor valves are spring loaded check valves.
True False
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Question 45 of 77.
Which methods are used on Ariel compressors to achieve proper clamping load? Select all that
apply.
Torque wrench
Torque-plus-turn
Heat
Hydraulic torque
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Question 46 of 77.
What is most of the effort trying to overcome when torquing a bolt that has not been lubricated?
Select both correct answers.
Head friction
Bolt material properties
Torque wrench accuracy error
Bolt thread friction
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Question 47 of 77.
The correct torque for a JGK main bearing cap bolt is _____ Lb x Ft.
230
280
310
90 plus 90 degrees of turn
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Question 48 of 77.
When a bolt is over-torqued, threads are under-stretched, the bolt does not seat correctly against
the secured materials, and does not have the correct clamping force.
True False
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Question 49 of 77.
Where can correct Ariel bolt torque values can be found.
Associated frame Maintenance Manual
Ariel ER-63; Fastener Torques for Reciprocating Compressors
Call the Ariel Response Center (ARC)
All of the above
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Question 50 of 77.
A torque wrench measures torque as a proxy for bolt tension to achieve proper loading and
clamping force.
True False
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Question 51 of 77.
What is the correct torque value for the force feed lubrication system rupture disc assembly?
______ Lb x In.
25
40
50
75
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Question 52 of 77.
What is the purpose of using the Ariel specified lubricant on threaded fasteners?
Obtain specified bolt preload
Prevent galling and seizing
Prevent rust and corrosion
Overcome friction forces
All of the above
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Question 53 of 77.
Which of these items must be known to operate, maintain, and troubleshoot an Ariel compressor
package?
Discharge Pressure
Elevation
Suction temperature
Gas cooler temperature
All of the above
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Question 54 of 77.
With a constant compression ratio the gas discharge temperature decreases if the suction
temperature drops.
True False
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Question 55 of 77.
With a constant clearance volume the volumetric efficiency will be constant with different gasses.
True False
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Question 56 of 77.
Which compressor operational configuration is most likely to cause a non-reversal condition?
Double acting cylinder with all valves installed
Single acting cylinder with Crank End (CE) suction valves removed
Single acting cylinder with Head End (HE) suction valves removed
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Question 57 of 77.
Rod Load Tension is when the piston is compressing gas on the outboard Head End of the
cylinder.
True False
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Question 58 of 77.
What is "Unbalanced Force"?
An energy source that tries to pull the entire machine and foundation first in one direction and then
in the opposite direction.
An energy source once per revolution.
An energy source twice per revolution.
An energy source that tries to make the machine oscillate about an axis.
None of the above
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Question 59 of 77.
Soft foot checks are performed to verify or correct main bearing alignment and are required for an
Ariel JGK/4 when setting the unit and during 8000 hour maintenance inspections.
True False
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Question 60 of 77.
What methods are used to align compressor and driver shafts. Select the three most used
methods.
Laser
Rim and Face
Reverse Indicator
Feeler Gauge and Tape Measure
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Question 61 of 77.
Which of the following could indicate a driver to compressor alignment issue?
Advanced main bearing wear
Worn thrust bearing plates
Vibration
High compressor frame oil temperature
All of the above
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Question 62 of 77.
List two pieces of information that are needed to perform a shaft alignment with dial indicators
using the Rim and Face method.
Indicator sag
Thermal growth; compressor and driver
Length of driver shaft
Compressor cylinder weights
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Question 63 of 77.
Coupling disc packs in compression mean what?
The driver and compressor are mounted too close together.
The driver and compressor are mounted too far apart.
This is a normal disc pack configuration.
The driver or compressor is mounted too high in relation to the other unit.
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Question 64 of 77.
Pipe stress has no effect on the compressor.
True False
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Question 65 of 77.
The packing case tie studs are not equally spaced which allows the ring cups to go on in only one
way.
True False
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Question 66 of 77.
When rebuilding a piston rod packing case, the letters on the ring sets typically face which
direction?
Away from the pressure
Towards the pressure
The rings alternate so that one side faces away and the other faces toward the pressure
Direction the packing case ring letters face is not important
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Question 67 of 77.
The piston rod packing case restricts the flow of gas out of the cylinder to ensure any vented gas
goes to a safe location.
True False
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Question 68 of 77.
Piston wear bands seal gas pressure across the piston.
True False
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Question 69 of 77.
The side notches on the compressor piston wear band prevent it from energizing as a seal ring.
True False
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Question 70 of 77.
The packing case restricts the flow of gas from escaping around the piston rod.
True False
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Question 71 of 77.
What causes excessive piston ring leakage?
Worn piston rings
Cylinder out of round
Taper of the piston ring groove
All of the above
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Question 72 of 77.
What is a possible cause for gas escaping the distance piece vent but not through the primary
vent from the packing case?
Packing case vent is plugged
Packing case bolts are loose
Leaking packing case nose gasket
All of the above
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Question 73 of 77.
Compressor terms throw and stage refer to the same thing.
True False
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Question 74 of 77.
There can not be more than four cylinders in a stage of compression.
True False
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Question 75 of 77.
The main bearings and connecting rod bearings are steel backed aluminum.
True False
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Question 76 of 77.
Throw number 1 on every Ariel compressor is located closest to the driver.
True False
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Question 77 of 77.
All Ariel compressor frame models use spacer bars.
True False
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