MILLWRIGHT ALBERTA PERIOD 3 FINAL EXAM STUDY GUIDE |
QUESTIONS AND ANSWERS | VERIFIED ANSWERS | LATEST EXAM
What are the 2 main categories of screw compressor - CORRECT ANSWER-
Oil wet and oil free dry screw comp
Witch rotor is the driver on a screw compressor - CORRECT ANSWER- The
male rotor
What determines the capacity of a screw compressor - CORRECT ANSWER-
Rotor length, diameter, lobe flute design and speed
What determines the discharge pressure of a screw compressor - CORRECT
ANSWER- The location of the inlet port along the rotor, the length of path and
the discharge port location
What function does the oil in a wet screw compressor serve - CORRECT
ANSWER- Remove heat, seal gaps to prevent leakage, lubricate and reduce
noise
What is the simplest type of control system in a screw compressor -
CORRECT ANSWER- Online/offline control
Which control system allows the compressor to produce only the amount of air
required - CORRECT ANSWER- Modulation control
What must be included to prevent rotor contact on a dry screw compressor -
CORRECT ANSWER- Timing gears need to be used
,Where are the thrust bearings located on a screw compressor - CORRECT
ANSWER- On the discharge side
Air filter should be able to remove particles down to what size before air enters
the compressor - CORRECT ANSWER- 5 microns
What two functions do oil separators perform - CORRECT ANSWER- Oil
separation from air, acts as an oil reservoir
What two functions do the minimum pressure valve perform - CORRECT
ANSWER- Maintain a minimum air pressure in separator, acts as a check valve
preventing flow reversal
What is the function of the thermal mixing valve - CORRECT ANSWER- To
maintain a minimum oil injection temp
What is the advantage of the helical lobe blower vs the 2 lobe blower -
CORRECT ANSWER- Increases Pr and smother air delivery
Only helical lobe blowers need timing gears - CORRECT ANSWER- False
What should be done first before putting a compressor back into service after an
overhaul or motor change - CORRECT ANSWER- Check for correct rotation
after motor or air unit replacement
Lobe blowers are used to produce high Pr and low volume - CORRECT
ANSWER- False
What should be done before resetting the timing on a lobe blower - CORRECT
ANSWER- Determine whether the unit is unidirectional or bi directional
rotation
, What should be done before starting a blower after an overhaul - CORRECT
ANSWER- Turn it over by hand to ensure that it rotates freely in the direction
of rotation
Care should be taken to prevent what from happening while you are attempting
to set the lobe clearences - CORRECT ANSWER- Take care to prevent pinch
points and injury
What type of compressor is flooded with oil all the time it's running -
CORRECT ANSWER- Wet vain
How do babe compressor systems often eliminate the need for a receiver -
CORRECT ANSWER- By using an inlet throttling control system
What is the only major moving part in a sliding vain compressor - CORRECT
ANSWER- Rotor assembly
What does it mean for a compressor to have a built in pressure ratio -
CORRECT ANSWER- This pressure ratio is not adjustable as are
reciprocating compressor
What prevents the high Pr discharge air from leakage back into the low pressure
suction area in vane compressor - CORRECT ANSWER- Centrifugal force
along with an oil seal on the vain
How is compressor capacity determined on a vain compressor - CORRECT
ANSWER- By calculating the volume of air between the sets of vanes at max
volume x by the number of vanes x the rom of motor
QUESTIONS AND ANSWERS | VERIFIED ANSWERS | LATEST EXAM
What are the 2 main categories of screw compressor - CORRECT ANSWER-
Oil wet and oil free dry screw comp
Witch rotor is the driver on a screw compressor - CORRECT ANSWER- The
male rotor
What determines the capacity of a screw compressor - CORRECT ANSWER-
Rotor length, diameter, lobe flute design and speed
What determines the discharge pressure of a screw compressor - CORRECT
ANSWER- The location of the inlet port along the rotor, the length of path and
the discharge port location
What function does the oil in a wet screw compressor serve - CORRECT
ANSWER- Remove heat, seal gaps to prevent leakage, lubricate and reduce
noise
What is the simplest type of control system in a screw compressor -
CORRECT ANSWER- Online/offline control
Which control system allows the compressor to produce only the amount of air
required - CORRECT ANSWER- Modulation control
What must be included to prevent rotor contact on a dry screw compressor -
CORRECT ANSWER- Timing gears need to be used
,Where are the thrust bearings located on a screw compressor - CORRECT
ANSWER- On the discharge side
Air filter should be able to remove particles down to what size before air enters
the compressor - CORRECT ANSWER- 5 microns
What two functions do oil separators perform - CORRECT ANSWER- Oil
separation from air, acts as an oil reservoir
What two functions do the minimum pressure valve perform - CORRECT
ANSWER- Maintain a minimum air pressure in separator, acts as a check valve
preventing flow reversal
What is the function of the thermal mixing valve - CORRECT ANSWER- To
maintain a minimum oil injection temp
What is the advantage of the helical lobe blower vs the 2 lobe blower -
CORRECT ANSWER- Increases Pr and smother air delivery
Only helical lobe blowers need timing gears - CORRECT ANSWER- False
What should be done first before putting a compressor back into service after an
overhaul or motor change - CORRECT ANSWER- Check for correct rotation
after motor or air unit replacement
Lobe blowers are used to produce high Pr and low volume - CORRECT
ANSWER- False
What should be done before resetting the timing on a lobe blower - CORRECT
ANSWER- Determine whether the unit is unidirectional or bi directional
rotation
, What should be done before starting a blower after an overhaul - CORRECT
ANSWER- Turn it over by hand to ensure that it rotates freely in the direction
of rotation
Care should be taken to prevent what from happening while you are attempting
to set the lobe clearences - CORRECT ANSWER- Take care to prevent pinch
points and injury
What type of compressor is flooded with oil all the time it's running -
CORRECT ANSWER- Wet vain
How do babe compressor systems often eliminate the need for a receiver -
CORRECT ANSWER- By using an inlet throttling control system
What is the only major moving part in a sliding vain compressor - CORRECT
ANSWER- Rotor assembly
What does it mean for a compressor to have a built in pressure ratio -
CORRECT ANSWER- This pressure ratio is not adjustable as are
reciprocating compressor
What prevents the high Pr discharge air from leakage back into the low pressure
suction area in vane compressor - CORRECT ANSWER- Centrifugal force
along with an oil seal on the vain
How is compressor capacity determined on a vain compressor - CORRECT
ANSWER- By calculating the volume of air between the sets of vanes at max
volume x by the number of vanes x the rom of motor
