2ND 14

Question 1

If all other factors are held constant, the volume of a dry gas decreases:

a) in direct proportion to an increase in its pressure
b) when its pressure is decreased
c) in direct proportion to an increase in its temperature
d) as the square of the rate of the temperature increases

Answer 1

a) in direct proportion to an increase in its pressure

Question 2

Absolute pressure is equal to:

a) 14.7 psig
b) gauge pressure less 14.7
c) gauge pressure plus 14.7
d) gauge pressure plus altitude

Answer 2

c) gauge pressure plus 14.7

Question 3

If 500 cubic inches of gas under a pressure of 15 psia is compressed to 20 cubic inches, what will the new pressure be?
(Use formula 𝐏𝟐/𝐏𝟏=𝐕𝟏/V𝟐)

a) 2 psia
b) 375 psia
c) 667 psia
d) none of the above

Answer 3

b) 375 psia

Question 4

The quantity and pressure of air discharged from a centrifugal fan depends on the:

a) size of the fan rotor
b) speed of the fan rotor
c) density of the air
d) all three of the above

Answer 4

d) all three of the above

Question 5

Increasing the speed of an unbalanced shaft will:

a) move the center of gravity further from the axis of rotation thereby improving the balance
b) move the axis of rotation closer to the center of gravity
c) move the center of gravity further from the axis of rotation thereby increasing the unbalance
d) will have no affect on the location of the center of gravity

Answer 5

c) move the center of gravity further from the axis of rotation thereby increasing the unbalance

Question 6

Which of the following conditions would not normally contribute to a reciprocating air compressor explosion?

a) excessive recompression
b) excessive water accumulation
c) excessive lubrication
d) excessive compressed air demands

Answer 6

d) excessive compressed air demands

Question 7

Large reciprocating air compressors are generally unloaded while starting and stopping to:

a) prevent explosions
b) prevent excessive pressure from building up in receivers
c) prevent moisture carry-over into discharge lines
d) reduce the starting torque and permit more gradual stopping

Answer 7

d) reduce the starting torque and permit more gradual stopping

Question 8

The temperature at which molecules of water vapor begin to condense upon the surface of objects as air is cooled is called the:

a) saturation point
b) boiling point
c) dew point
d) relative humidity

Answer 8

c) dew point

Question 9

High outlet compressed air temperatures could be caused by all of the following except:

a) faulty valves and recompression
b) fouled cooling surfaces
c) low oil level
d) high inlet air temperatures

Answer 9

c) low oil level

Question 10

Air receivers are installed on all reciprocating air compressors to:

a) dampen pressure waves
b) reduce pressure drops
c) remove moisture or sludge
d) all of the above

Answer 10

d) all of the above