screw compressor

Question 1

dual rotor screw compressor requires timing gear to prevent rotor contact

Answer 1

dry screw or oil free

Question 2

dual rotor screw compressor uses injected oil to lubricate, the male rotor is usually driven and rotors are seperated by oil film

Answer 2

wet screw or oil flooded

Question 3

another name for screw compressor

Answer 3

helical lobe

Question 4

which is the drive rotor on a screw compressor

Answer 4

male rotor

Question 5

what determines a screw conveyors pressure ratio

Answer 5

discharge port location

Question 6

the main factor that reduces volumetric efficiency

Answer 6

back leakage

Question 7

how to decrease back leakage and increase volumetric efficiency

Answer 7

increase compressor speed

Question 8

4 things that determine compressor capacity

Answer 8

rotor length
diameter
lobe flute design
compressor speed

Question 9

how much more efficient are asymmetrical lobe profiles to symetrical lobe profiles

Answer 9

10-15%

Question 10

as the number of flutes increase

what happens to volume of air

Answer 10

decreases

Question 11

valve used to get minimum pressure on start up

Answer 11

minimum pressure valve

Question 12

emergency shutdown instrument , normal readings of 180-205 fahrenheit

Answer 12

discharge temperature probe

Question 13

valve acts as radiator for the purpose of keeping oil at required temperature

Answer 13

thermal mixing valve

Question 14

valve used to stop oil flow after compressor stops

Answer 14

oil stop valve

Question 15

valve that vent pressure from the separator on a shutdown to prevent oil from being pushed out of the compressor filter

Answer 15

blowdown valve

Question 16

3 ways to control capacity in a screw conveyor

Answer 16

suction throttling
rotating speed (modulation control)
displacement control (internal bypass)

Question 17

capacity control that controls suction flow or discharge pressure

Answer 17

suction throttling

Question 18

most common type of suction throttling

Answer 18

load/no load

Question 19

capacity control best used when load fluctuates between 60-100%

Answer 19

modulation control

Question 20

3 methods of displacement control

Answer 20

turn valve
poppet valve
slide valve