Module 2

Question 1

a compressor with mechanically separated inlet and discharge ports

Answer 1

Positive-displacement compressor

Question 2

a compressor with no method of separating inlet and discharge ports; permit free passage of air when not running

Answer 2

Dynamic compressor

Question 3

a type of compressor designed for high air volume rather than high pressure

Answer 3

Impeller (or blower)

Question 4

actual cubic feet per minute; compressor capacity measured at the intake when installed

Answer 4

Acfm

Question 5

standard cubic feet per minute; compressor capacity specified at standard intake conditions

Answer 5

Scfm

Question 6

Name the five kinds of positive displacement rotary compressor.

Answer 6

Sliding Vane
Dry screw
Wet screw
Liquid ring
Impeller

Question 7

A single-stage valve compressor can normally produce discharge pressures of _____ psi.

Answer 7

50

Question 8

Dry rotary-screw positive-displacement compressors have how many rotors?

Answer 8

Two

Question 9

Single-stage dry rotary-screw compressors normally produce discharge pressures of _____ psi.

Answer 9

50

Question 10

The mating lobes of a wet rotary-screw compressor are driven by the power source _____ timing gears.

Answer 10

Without (One lobe powers the other).

Question 11

The space where the air is compressed in a liquid-ring compressor is formed by _____.

Answer 11

Liquid

Question 12

Because of its low discharge pressure, an impeller compressor is often referred to as a _____.

Answer 12

Blower

Question 13

To prevent contact, the impellers of an impeller compressor are _____.

Answer 13

Timed by external gears

Question 14

The compressing impellers of a three-stage centrifugal compressor are mounted on a(n) _____.

Answer 14

Speed Increaser

Question 15

Most centrifugal compressors are equipped with _____ and _____ to prevent excessive air temperatures.

Answer 15

Intercoolers; Aftercoolers

Question 16

To be efficient, the rotors in dynamic compressors must rotate at _____ speeds.

Answer 16

High

Question 17

The discharge pressure of a multistage dynamic compressor is determined by the number of stages and the _____ per _____.

Answer 17

Pressure per Stage

Question 18

The most efficient method of controlling the output of centrifugal compressors is by _____.

Answer 18

Speed Variation

Question 19

The rotating blades of axial-flow compressors are positioned between stationary _____ blades.

Answer 19

Diffuser

Question 20

In plants having different compressed air requirements, it may be advantageous to install the compressor(s) in _____ location(s).

Answer 20

Several

Question 21

The term acfm may be referred to as _____ capacity.

Answer 21

Free air or Actual cubic feet per minute

Question 22

What is the maximum discharge pressure of a single-stage sliding-vane compressor?

Answer 22

50 psi

Question 23

What type of positive-displacement compressor is best suited for light-duty applications?

Answer 23

Diaphragm

Question 24

What type of compressor will deliver large amounts of oil-free air at approximately 100 psi?

Answer 24

Dry rotary-screw

Question 25

A centrifugal compressor is classified as a(n) _____ compressor.

Answer 25

Dynamic

Question 26

The compressing lobes of a wet rotary-screw compressor are driven without _____.

Answer 26

Timing gears.

Question 27

The impellers of centrifugal compressors rotate at high speeds to ensure _____.

Answer 27

Efficient operation

Question 28

Impeller compressors are frequently referred to as _____.

Answer 28

Blowers

Question 29

The most efficient method of controlling the output of a centrifugal compressor is by _____.

Answer 29

Speed variation

Question 30

Impeller compressors use the same operating principle as _____.

Answer 30

Gear pumps

Question 31

The term used to describe the measured capacity of a compressor after it is installed is _____.

Answer 31

Actual cubic feet per minute