Reciporcating compressors Flashcards
reciprocating compressor oil sumps are usually painted with an oil resistance coating to
keep the oil contaminants out of the oil
prevent corrosion
trap any casting sand that might be left in the sump
both the 2nd and 3rd answer is correct
Both second and third answers are correct
when designing a foundation, you must make sure that it
keeps the frame from distorting
allows proper alignment of the compressor to the driver
has sufficient mass and be isolated from rest of the building
all the above
All of the above
when doing a wire alignment on a compressor, you need to know _______________ to accomadate for wire sag between the 2 end points of the wire
the size of the wire and the weight of the wire
the size of the wire and the amount of weght attached to the end of the wire
the size of the wire, the amount of weight attached and the distance between the 2 end points
the wire will not have sag in it
the size of the wire, the amount of weight attached and the distance between the 2 end points
in a multi-stage compressor, to balance the inertial forces, pistons are
made of aluminium
heat treated
hollowed out
both the 1st and 3rd answer are correct
Both first and third answers are correct
chroming is done to rods and journal surfaces to make them long wearing
true
false
True
when balancing crankshafts you would_______________ to resolve reciprocating forces
use apposed throws and counter-weights
used apposed throws and add inertial forces
use counter weights traveling in the same direction as force
use counter-weights and add inertial forces
Use apposed throws and counter weights
if you could put a 0.002 feeler gage under the shaft at one of the main bearings, when the shaft is sitting in the bottom of all the main bearings, what would happen if you ran it this way
nothing, it is ok to run it this way
the bearings beside it would fail more quickly
the crank would have more axial float
oil flow would be minimal thru this bearing
The bearing beside it would fail more quickly
for every rvolution of the crankshaft you will have one suction stroke and one compression stroke. this would be a
double acting piston
single acting piston
Single acting piston
piston rods
are used to join the piston to the crosshead
are chrome plated to increase their life
are screwed into and locked onto the crosshead with a nut
all the above
All of the above
rod loading is when the rod
is under compression
is under tension
both the 1st and 2nd answers are correct
none of the above
Both first and second answers are correct
rod reversal is
the reversal of the rod laod from compression to tension
good for lubrication
improved with a tail rod
all the above
All of the above
excessive rod loading does ____________________ to happen
not allow misalignment
not allow corrosion
not allow full film lubrication
allows full film lubrication
Not allow full film lubrication
in a double acting piston, when the piston is at TDC, the valves are_____________
open
closed
open and closed
none of the above
Closed
no oil rings exist on double-acting compressors or non-lubricated compressors
true
False
True
cast iron piston rings are used because
they are cheap
they are brittle
they conform quickly and are self-lubricating
both the 1st and 3rd answers are correct
First and Third answers are correct
oil control rings control the flow of oil on cylinder walls by
allowing oil to flow onto the wall on the up-stroke thru holes in the ring
scraping oil off the cylinder walls with the oil ring
not having an expasion ring
both the 1st and 2nd answer are correct
Both first and second answers are correct
installation of piston rings should have the gap staggered _______ degrees when the piston has 2 pressure rings
90
45
180
360
180 degrees
synthetic rings out last metallic rings in enviroments such as
abrasion
acidic gasses
corrosion
all the above
All of the above
you would check for piston ring end gap when the ring is
on the psiton and the piston is in the cylinder
in the cylinder at the smallest diameter
on the piston in the piston groove
on the bench without being installed on anything
In the cylinder at the smallest diameter
piston rider bands
prevent the piston from touching cylinder during startup and operation
support 100% of the piston weight and 100% of the piston rod weght
have a tongue and groove cut ring
all the above
Prevents the piston from touching the cylinder during start up and operation
uncut rider bands are machined with a interference fit. when stretched on and into their grooves, they will
shrink to a snug fit in the groove
stay loose in the groove
need a backup ring to support it
both the 2nd and 3rd answers are correct
shrink to a snug fit in the groove
a special clamping device and torque multiplier will be needed to install the ___________ into the ______________
rod, crosshead
rod, piston
crosshead, crankshaft
crankshaft, rod
Rod, Piston
the piston rod is screwed into the crosshead and locked in place with
lock nuts
balancing nuts
set screws and lock wire with the lock nut
all the above
All of the above
when removing the piston and rod from the crosshead and out of the cylinder, you will
need to record the number of turns to remove the rod from the crosshead
rotate the driver to move the crosshead out of the way
carefully pull piston and rod out thru the cylinder without scoring it
all the above
all of the above
if setting the piston clearances, when the compressor is cold, you will
set the crank head clearance at 2/3 and the head end clearance to 1/3 of the total clearance
set the crank head clearance to 1/3 and the head end clearance to 2/3 of the total clearance
set both head end and crank head clearance to 50%
make sure there is no contact at either end
Set the crank head clearance at 1/3 and the head end clearance to 2/3 of the total clearance
_________________ are used to fine tune the weight balancing of opposing multi-stage reciprocating compressor parts
balancing nuts
lock nuts
set screws
lock wires
Balancing nuts `
clearance pockets can be fixed or variable and they
help match the output of the compressor to the demand of the system
can be a plug or bottle type
can be VVCP
all the above
all of the above
when reversing a clearance plug, the compressor capacity will be
increased
reduced
stay the same
none of the above
Reduced
you can only adjust the VVCP when the compressor is running
true
false
False
when not running
hydro-testing a cylinder, you would pressurize the cylinder to 1.5 times the max working pressure
true
false
True
when you have a large industrial compressor with a cylinder of 3 meters extending from the main frame, you will need to support it so the frame and distance piece do not take all the load or weight. the support is pre-loaded to take some of the weght
true
false
True
what is the shim move needed if R = 0.01, L = 36”, S = 6” R/S=X/L X= shim move
0.050
0.060”
0.075”
00.80”
0.060
the packing prevents excessive leakage of compressed gas along the piston rod and into the distance piece
true
false
True
free floating mechanical packing
moves in all directions
has cups
has segmental sealing rings
all the above
All of the above
which of the following is NOT a type of packing ring
pressure breaker
radial cut
tangential cut
cup cut
Cup cut
the pressure breaker ring is located
in the middle of the packing
closest to the frame
closest to the cylinder
does not matter
Closest to the cylinder
on low pressure single sealing (one-direction) the radial ring is doweled to the tangent ring. the radial ring must be installed on the pressure side with the markings (dots) on both rings facing the pressure side
true
false
True
the double acting ring combination, seals in both directions
true
false
True
packing case design is dictated by type of application, pressure and compressor speed, this will determine
the # of cups and rings
if cooling is needed
if lubrication is needed
all the above
All of the above
cup joints can be lapped with an O-ring, gasket joint or tongue and groove which helps seal between the cup faces
true
false
True
when using lubricated and vented packing, the vent is located on the
top
bottom
Bottom
the oil wiper ring is located
next to the cylinder in the distance piece
middle of the distance piece
crank side of the distance piece
anywhere in the distance piece
Crank side of the distance piece
in operation, the 1st oil wiper ring turns back most of the oil to the crankcase and the rest is scraped off by the internal scraping of the ring
true
false
True
the distance piece is used to
prevent cylinder leakage from pressurizing the main frame
prevent oil from the crankcase getting into the cylinder
access the packing, wipers and checking rod runout
all the above
All of the above
you could use a 2 compartment distance piece to totally seal off an explosive gas coming form the compressor chamber
true
false
True
the purpose of the crosshead is to centre the piston rod in the packing case
true
false
True
adjustable crossheads with removable shoes can use shims at the bolt locations to alter the clearance between the crosshead and guides
True
the rod nut face must be smooth and free of burrs and dirt. the mating face of the lock nut should be perpendicular to the rod nut face
true
False
False
must be parallel
the lock nut is used to adjust the position of the piston by allowing the piston rod to turn into and out of the crosshead
true
False
True
the connecting rod has a bias cut when you have to pull the the connecting rod thru the cylinder bore
true
False
True
you need dowel pins on both sides of the parting line of the rod cap to hold the 2 halves in proper alignment
true
False
True
when taking the connecting rod out, make sure to match mark the 2 pieces
true
false
True
if plasitigage is not reading the proper clearance, you would look at __________ as the cause
dirt under the bearing insert
wrong size of bearing insert
beraring insert caught on tag or tap
all the above
All of the above
when using locking plates to retain the crosshead pin, the device requires connecting rod and crosshead to be separated before pulling the unit
true
false
False
Cannot remove beforehand?????
with single a single acting compressor, you must remove the connecting rod thru the cylinder
true
True
oil starvation to the bearings causes the bearing surfaces to
over heat
wipe away
have their clearances decrease
both the 1st and 2nd answers are correct
Both the first and second answers are correct
measurments taken between the crosshead and guides should measure between ____________”
0.12 to 0.15
0.17 to 0.20
0.007 to 0.010
0.001 to 0.002
.007 to .010
to check for rod runout, you would put the dial indictor on top of the rod in the distance piece and cycle the crankshaft form BDC to TDC
true
false
True
the largest factor effecting a compressors efficiency is
piston and ring wear
leaky packing
improper valve operation
the clearance volume
Improper valve operation
the 4 components of compressor valves are sealing element, valve seat, assembly elements and valve gaurd
true
false
True
when using v-shape rings and flat rings for cylinder head valves, which one has a smoother flow path and less chance of deposits forming
v-shape
flat
no difference
V-Shaped
for the size of the valve, which valve allows for the least restriction to flow, since there are no flow reducing webs
ring
plate
Ring
dampen disc valves are used to reduce compressor valve flutter
true
false
True
alve flutter is a condition where the sealing element rebounds off the piston
true
false
False
Look up right answer
feather valves do not use
pressure differential to move the strip
suction
springs
all the above
Springs
bringing cooling water temperatures to above incoming gas temperatures will
prevent slugs
cause condensation in the cylinders
cause coking
all the above
Prevent plugs
coking is caused by
too much water on a hot discharge valve
too much oil on a hot discharge valve
lack of heat of compression
valve flutter
to much oil on hot discharge valve
too little lift in a sealing element will cause ____________________ which causes lower compressor capacity
an increase in both horsepower and gas temperature
increased valve wear
leaky valves
an increase in compressor capacity
An increase in both horsepower and gas temperature
to test compressor valves and their seats for leakage, you would ___________________ and tap the valve plate and seat to clean the seal area after a slight pressure build up during the test
use a pressure drop test
use a flow meter test
use a HP test
both the 1st and 2nd answer are correct
Both first and second answers are correct
when removing valves from a reciprocating compressor, you should make sure to vent the cylinder by backing off the valve cover nuts a few turns and tapping the cover to jar it loose from its seat
true
false
True
valve covers should have some clearance between them and the cylinder housing after the bolts are torqued
true
false
True
there is very little physicl difference between suction and discharge valves except the direction they are orientated. you can check for orientation by pushing on the sealing element. a discharge valve will open _____________________
away from the nut
towards the nut
Towards the nut
in oil systems, the most important aspect of oil in a compressor system is the oils viscosity
true
false
True
the best oil system for double acting compressors is
splash
gravity
splash and gravity
full pressure
Full pressure
pressure in a positive displacement pump system is created by the
pump
maximum pressure relief valve
bearing clearances
none of the above
Bearing clearances
the maximum pressure relief valve is there to protect the compressor oil system from excessive lube pressure
true
False
True
filter systems for the lube system are usually
partial flow
full flow
mixed flow
unfiltered
Full flow
metered oil is used in the
packing cases
main frame
cylinders
both the 1st and 3rd answers are correct
Both first and third answers are correct
divider valves ae used to supply metered oil to many points with 1 pump
true
false
True
the divider block lubrication system cannot tolerate dirt, air, gas or leaks. it must b full of oil and free of air to work properly
true
false
True
you would use a venture silencer with paper filter elements with a
screw compresor
vane compressor
reciprocating compressor
none of the above
Reciprocating compressor
the filter that spins the dirty incoming air to help separate the dirt from the air is the
fabric
oil-wetted labyrinth
scrubber
inertial
Inertial
when cylinder cooling, the coolant should start near the discharge vlaves and exit near the suction valves
true
false
True
piston rod run out would have a proximity sensor that would measure rod drop
true
False
True
by opening a clearance pocket to a larger size in a compressor, you would
increase its capacity
decrease its capacity
increase valve lift
decrease valve lift
Decrease its capacity
valve designs for high speed compresors will have
high lift valves
wide ports
low lift valves
no ports
Low lift valves
the minimum, H2S gas amount that could kill you within 8 to 48 hrs is
0.010 %
0.050 %
00.40 %
0.030 %
0.010
filling out permits will alert you to potential dangers that may be overlooked and ensures you will follow established safety routines. you will also meet with everyone involved to review the safety procedures
true
false
True
following manufactures specifications will help you with understanding the procedures involved
true
False
True
OEM is the best place to find someone with equipment knowledge and system knowledge of their equipment
true
false
True
organizing parts and labeling of the parts will help your team (when different people will be working on the same equipment at different times or shifts)
true
false
True
rotating crankshafts when compressors are in storage, would help stop
brinelling
false brinelling
spalling
flaking
False brinelling
before starting up a large compressor, you should make sure to __________ after an overhaul or on a first start up
prelube the bearings
check rotation of prime mover and compressor
bar compressor over a full 360 degrees
all the above
all of the above
when starting a compressor, you must shut down the compressor immediately (within 5 seconds of not having oil pressure)— normally about 45 psi
true
False
True
rapidly wearing packing could be caused by an incompatible gas being compressed
true
False
True
when doing a flush of the lubrication system in a reciprocating compressor system, it is necessary to bar over the compressor a 1/4 of a rotation every 15 to 20 minutes during this flush
true
false
True
a tail rod is used to equalize the surface area which reduces tha capacity of the compressor but ensures rod reversal
true
false
True
failure analysis collects and analyzes data to find out the causes of a failure. operator logs are an excellent source of info for analysis
true
False
True
changes in oil sample readings can help detect
wear rates of bearings
the oils viscosity and additive levels
the filters efficiency level
all the above
All of the above
why should you check for proper rotation if a 3 phase motor drives the compressor and it was replaced
compressor is driven in the proper direction
lube pump driven in proper direction
the wires could be reversed
all the above
All of the above
labyrinth compressors use ___________to help control pressure drop across the cylinder wall and piston
piston rings
oil rings
grooves on the cylinder and piston
all the above
Grooves on the cylinder and pistons
diaphragm compressors are used where _______________is needed
pulsation free air is needed
oil free air is needed
leakage is acceptable
all the above
Oil free air is needed
intercoolers are used to
cool the compressed air between stages
decrease the amount of power required to compress the gas
remove moisture from the air
all the above
All of the above
displacement is
the total volume of air moved out of the compressor cylinder
the total volume of air the compressor compresses divided by the compression ratio
the total volume of air moved out of the compressor cylinder in a given unit of time
total volume of air the compressor takes in divided by the compression ratio in a given unit of time
the total volume of air moved out of the compressor cylinder in a given unit of time
swept volume
is equal to the area of the piston area times the length of stroke
does not include the clearance volume
includes venting
both the first and second answers are correct
Both first and second answers are correct
the difference between venting and purging is
venting is pressure release while purging is cleaning the system with inert gas
venting is cleaning the system with inert gas while purging is pressure release
they both mean the same thing
all the above
venting is pressure release while purging is cleaning the system with inert gas
