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Refrigeration 2nd Year > Shop > Flashcards

Shop Flashcards

1
Q

Current relay type of wire and resistance

A

Heavy wire low resistance

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2
Q

Current relay S=?

A

S= start

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3
Q

Current relay L=?

A

L=Line voltage

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4
Q

Current relay M=?

A

M=run

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5
Q

In a current relay what position are L and S

A

Normally open

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6
Q

Potential relay what is it called when the coil is energized?

A

Pick up voltage

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7
Q

What shuts off a potential relay secondary coil after being energize?

A

Back EMF

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8
Q

What kind of resistance does a solid state relay have?

A

Low resistance

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9
Q

Order of calculating open compressor pulleys?

A

2 sames on top divided by the one by itself

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10
Q

Liquid charge and cross charge have a MOP

A

NO

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11
Q

Height limit for evaporators away from condensing units

A

20 feet

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12
Q

Hot gas bypass line sizing should not exceed a

A

6-12 psi pressure drop

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13
Q

Bypass pressure activation

A

58 psig

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14
Q

How does hot gas bypass valve open

A

Open of differential pressure ORD

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15
Q

When using hot gas bypass for capacity control what must be used

A

De superheating TXV is liquid injector valve

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16
Q

Should hot gas bypass line be insulated?

A

Yes

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17
Q

Is hot gas bypass the last unloader

A

Yes

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18
Q

What kind of valve operates heat reclaim

A

Pilot operated valve

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19
Q

Are head pressure control valves necessary when using heat reclaim valves

A

Yes

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20
Q

Epr and cpr shouldn’t be together

A

More often than not

21
Q

When does a CPR close

A

Closes on a rise of outlet pressure

22
Q

CPR is normally?

A

Open

23
Q

What amps is the cpr set for

A

FLA or 10% higher than RLA

24
Q

Where is a CPR installed?

A

Always downstream of other control devices

25
Q

EPR opens…

A

On a rise of inlet pressure

26
Q

What is a common hold back valve?

A

An EPR

27
Q

Can an epr be considered a 2 temperature valve?

A

Yes

28
Q

What does an EPR maintain

A

A minimum evaporator pressure

29
Q

Epr keeps a constant pressure

A

No it doesn’t

It limits the minimum evaporator pressure

30
Q

Where must a EPR be installed

A

Upstream of all suction controllers devices

31
Q

What is a hear pressure control also known as

A

A low ambient control LAC

32
Q

Head pressure control helps…

A

Oil return to the comp

Prevent TXV hunting

33
Q

OROA=

A

Headmaster

34
Q

Head pressure control opens…

A

On a rise of outlet pressure

35
Q

Head pressure control is usually used on temperature operated systems or pressure controlled systems

A

Temperature

36
Q

Valve selection pressure drop should be in between…

A

2 abs 14psig

37
Q

2 types of receivers

A

Flow though

Surge type

38
Q

Receivers capacity and temperature

A

90% at 90F

39
Q

How much % must a distributor be able to handle

A

50-200%

40
Q

Oil filters must be mounted…

A

Vertically

41
Q

At what pressure drop should you replace a filter?

A

40-50psig

42
Q

3 types of oil separators

A

Helical
Impingement
Coalescing

43
Q

Mixing valve mixed how many things

A

2

44
Q

Diverted valve

A

1in 2 out

45
Q

Direct acting solenoid valve is how small

A

1/4 or less

46
Q

3 way solenoid valve/mixing valve
Heat reclaim
Split condenser and 2 more

A

Hot gas defrost

Pilot control valve

47
Q

3 types of desiccant

A

Loose fill
Compressed beads
Solid core

48
Q

Adjust clockwise an epr what happens

A

Increase set point of valve

49
Q

Clock wise on a cpr

A

In increases

Refrigeration 2nd Year (13 decks)

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