Compressor Pre-test quiz 1 Flashcards Preview

Compressors Exam > Compressor Pre-test quiz 1 > Flashcards

Flashcards in Compressor Pre-test quiz 1 Deck (28)
Loading flashcards...
1

The function of a compressor is to take refrigerant vapour at a ______ temperature and pressure and change it to a _____ pressure and temperature

low

high

2

At a constant RPM, a compressor is a _____ displacement device and its capacity is variable depending on the _______ of the refrigerant at the intake of the pump

constant

pressure

3

the reciprocating compressor has a built - in problem with efficiency, that is a portion of the discharge gas does not escape the cylinder and must re-expand before the suction gas can enter. The problem is caused by the ______ _______ which is designed in to the compressor to prevent _______

clearance pocket

contact between piston and valve plate

4

A mechanical shaft seal is required in a _________ compressor

open type compressor

5

All refrigeration compressor valves are opened and closed by ___________

pressure differential

6

How does a compressor initiate flow in a system?

a) by raising pressure in the evaporator
b) lowering pressure in the evaporator
c) by discharging liquid
d) raising pressure in the condenser

by lowering pressure in the evaporator

by raising pressure in condenser

7

In this compressor, a piston travels back and forth within a cylinder?

reciprocating

8

In this compressor two offset spiral disks compress refrigerant vapour

Scroll

9

This compressor has high speed impeller with many blades. The impeller rotates within a housing

centrifugal

10

This compressor has a pair of helical rotors. They trap and compresses gases as they revolve in a cylinder.

Screw

11

What is the fundamental difference between and hermetic and semi-hermetic compressor with regards to mechanical field service?

hermetic is much harder to service due to its metal housing

12

Most of the heat energy in the suction vapour entering the compressor is:

a) heat of compression
b) sensible heat
c) latent heat
d) defrost heat

latent heat

13

List four types of compressors

hermetic

semi hermetic

open drive

belt drive

14

As suction pressure increases the amount of refrigerant pumped ________ because the specific volume of the refrigerant ________

increases

decreases

15

List the types of compressor body styles?

hermetic

semi hermetic

open drive

16

Explain what is meant by saying the compressor rides with the load?

suction pressure goes up, density goes up, capacity goes up, specific volume goes down and volumetric flow rate is constant

17

List thee ways mechanical cylinder unloading is accomplished?

discharge bypass, suction cutoff, hydraulic

18

The cylinder unloader method of capacity control is used mainly with?

centrifugal

screw

rotary

none of the above

none of the above

19

In a scroll compressor;

a) both scrolls move
b) only the upper scroll moves
c) only the lower scroll moves
d) neither scroll moves

only the lower scroll moves

20

the capacity of a compressor is related to;

a) the speed of the driving motor
b) the compressor displacement
c) number of cylinders
d) all of the above

all of the above

21

The on/off method of capacity control is normally used with?

a) reciprocating, rotary, and scroll multi-compressor systems
b) rotary compressors
c) scroll compressors

a) reciprocating , rotary, and scroll multi-compressor systems

22

Excessive foaming in the oil sight glass shows the oil is

a) mixed with refrigerant
b) air
c) acid
d) all of the above

mixed with refrigerant

23

The contaminants present in a clean system are

a) moisture
b) air
c) acid
d) none of the above

none of the above

24

Match the type or Capacity control used with the appropriate compressor type;

1. Motor speed control
2. Cylinder unloading
3. on off cycling
4. sliding vanes
5. inlet vanes

Reciprocating?

1,2,3

25

Match the type or Capacity control used with the appropriate compressor type;

1. Motor speed control
2. Cylinder unloading
3. on off cycling
4. sliding vanes
5. inlet vanes

Rotary?

1,3

26

Match the type or Capacity control used with the appropriate compressor type;

1. Motor speed control
2. Cylinder unloading
3. on off cycling
4. sliding vanes
5. inlet vanes

Scroll?

1,3

27

Match the type or Capacity control used with the appropriate compressor type;

1. Motor speed control
2. Cylinder unloading
3. on off cycling
4. sliding vanes
5. inlet vanes

Screw?

1,4

28

Match the type or Capacity control used with the appropriate compressor type;

1. Motor speed control
2. Cylinder unloading
3. on off cycling
4. sliding vanes
5. inlet vanes

Centrifugal?

1,5