RACT unit 23

Question 1

Using two compressors can lower the ________ temperature and increases efficiency

Answer 1

discharge

Question 2

______ refrigerant passes through the suction valve of the compressor to fill the cylinders

Answer 2

cool

Question 3

Reciprocating compressors are used most frequently in _____ and _____ sized commercial refrigeration systems

Answer 3

small and medium

Question 4

The screw compressor is used in ______ commercial and _______ systems

Answer 4

large commercial and industrial systems

Question 5

The rotary, the scroll, along with the reciprocating compressors are used in ________ and light commercial air conditioning

Answer 5

residential

Question 6

Centrifugal compressors are used extensively for ___________ in large buildings

Answer 6

air-conditioning

Question 7

A hermetic reciprocating compressor has a __________ mechanism. The same shaft drives the compressor and motor

Answer 7

direct drive

Question 8

Difference between hermetic and semi hermetic

Answer 8

hermetic is welded and semi-hermetic is serviceable

Question 9

What is the only way to service a hermetic compressor?

Answer 9

cutting open the shell

Question 10

hermetic compressors usually have a _____________ system but smaller hermetics are splash lubricated

Answer 10

pressure lubrication

Question 11

semi hermetic compressors are ______ together so that it is easier to service and repair

Answer 11

bolted

Question 12

smaller semi hermitic compressor use _______ lubrication

Answer 12

splash type

Question 13

larger semi hermetic compressors use ________ lubrication

Answer 13

pressure

Question 14

Motor and crankshaft are connected in a semi hermetic compressor although the ________ is usually horizontal

Answer 14

crankshaft

Question 15

Open drive compressors are manufactured in two styles; ______ drive and ______ drive

Answer 15

belt driven and direct drive

Question 16

Any compressor with the drive on the outside of the casting must have a ____ _____ to keep the refrigerant from escaping

Answer 16

shaft seal

Question 17

rotary screw compressor has an open _____

Answer 17

motor

Question 18

In a screw compressor, a ______ seal traps refrigerant in the compressor housing where the rotating shaft leaves the housing

Answer 18

shaft

Question 19

Screw compressors are used in ______ systems

Answer 19

large

Question 20

The ________ of a reciprocating compressor transmits the circular motion of the rods into a back-and-forth motion for the pistons

Answer 20

crankshaft

Question 21

Crankshafts are normally manufactured or _____ iron or _____

Answer 21

cast iron or steel

Question 22

The off-centre shafts normally have _____ main bearing surfaces. One is on the _____ end and the other on the other end

Answer 22

two

motor

Question 23

some reciprocating compressor crankshafts are straight and have a cam-type arrangement called an ________

Answer 23

eccentric

Question 24

All reciprocating compressor shafts must be ________

Answer 24

lubricated

Question 25

Smaller reciprocating compressors using the splash system may have a ______ basin to catch oil and

Answer 25

catch

Question 26

In a reciprocating compressor, when the compressor runs the oil is then slung to the outside of the __________ surface

Answer 26

crankshaft

Question 27

(Recip) Connecting rods connect the ________ to the ______

Answer 27

crankshaft to the piston

Question 28

(reciprocating) Two types of connecting rods; one fits the _______ with off centre throws and the other fits the ________ crankshaft

Answer 28

crankshaft eccentric

Question 29

(recip) rods with large holes in the shaft end are for ______ shafts

Answer 29

eccentric

Question 30

The ______ is the part of the cylinder assembly exposed to the high pressure gas during compression

Answer 30

piston

Question 31

Pistons have high pressure gas on _____ and suction or low pressure gas on the ______

Answer 31

top bottom

Question 32

Piston rings are used on the larger pistons and are of two types; _______ and ____

Answer 32

compression and oil

Question 33

Smaller compressors use the oil on the cylinder walls as a _____

Answer 33

seal

Question 34

The valves in the top of the compressor determine the _______ the gas entering the compressor will flow

Answer 34

direction

Question 35

Reed valves and ring valves serve both the _____ and _______ ports of the compressor

Answer 35

suction and discharge ports

Question 36

The _____ _____ holds the suction and discharge flapper valves

Answer 36

valve plate

Question 37

Heads need to accomplish two things;

Answer 37

hold the pressure in and hold the valve plate on the cylinder

Question 38

Mufflers are used in many fully _______ compressors to muffle compressor pulsation noise

Answer 38

hermetic

Question 39

Compressor housing holds the compressor and sometimes the ______

Answer 39

motor

Question 40

Internal ________ protection devices in hermetic motors protect the motor from overheating

Answer 40

overload

Question 41

open drive compressors are manufactured with the motor external to the __________ shell

Answer 41

compressor

Question 42

the shaft protrudes through the casing to the outside where either a _____ or _______ is attached

Answer 42

pulley or coupling

Question 43

The pulley on the motor of a belt drive compressor is called the ______ pulley

Answer 43

drive

Question 44

The pulley on the compressor of a belt-drive compressor is called the _______ pulley

Answer 44

driven

Question 45

On a belt drive compressor, the drive pulley is sometimes adjustable, which allows the compressor ______ to be adjusted

Answer 45

speed

Question 46

direct drive compressors at limited to the _____ speed that the drive motor is turning

Answer 46

motor

Question 47

direct drive compressors can be ______ and serviced in place

Answer 47

rebuilt

Question 48

The closer tolerance makes the compressor more efficient because it reduces the ______________

Answer 48

clearance volume

Question 49

Scroll compressors conduct their ______, compression, and discharge phases simultaneously

Answer 49

intake

Question 50

Scroll compressor is known as a ____________________ type because the scroll compressor compresses the discharge gas to a zero volume

Answer 50

fixed compression ratio

Question 51

Scroll compressors have the ability to handle some ______

Answer 51

liquid

Question 52

Scroll type compressors are gaining popularity due to the efficiency, _______, and quieter operations

Answer 52

reliability

Question 53

The rotor shaft and impellers are the only moving parts in the _________ compressor

Answer 53

centrifugal

Question 54

Soft starting reduces __________ currents at start up

Answer 54

high inrush

Question 55

The centrifugal compressor is ___ free

Answer 55

oil

Question 56

In a centrifugal compressor, the rotor shaft has ___________ levitated bearings for frictionless operation

Answer 56

magnetically

Question 57

When small amounts of liquid enter the compressor it ______ the oil which means no lubrication and can cause the compressor to fail

Answer 57

dilute

Question 58

A dirty evaporator will cause the suction pressure to _____

Answer 58

drop

Question 59

Most manufacturers recommend that the compression ratio not be more than ___:1

Answer 59

10:1

Question 60

Dirty condensers and dirty evaporators cause the ______________ to rise

Answer 60

compression ratio

Question 61

Dirty condenser means high _____ pressure

Answer 61

head

Question 62

dirty evaporator means ____ suction pressure

Answer 62

low