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Refrigeration IP Prep > Review Questions Set 1 > Flashcards

Review Questions Set 1 Flashcards

1
Q

What temp is Brine kept at for ice?

A

15-20F

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2
Q

What orientation are vibersorbers installed

A

parallel to the crankshaft

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3
Q

vapor barriers are installed on which side of the walk in cooler wall

A

warmest side

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4
Q

what filter is used to remove odours

A

carbon filter

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5
Q

what is the purpose of a double suction riser

A

oil entrainment at minimum capacity load conditions

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6
Q

how do you test an oil failure control

A

jumper out terminals 1 and 2

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7
Q

when decommissioning a unit, what state should the coil be left in

A

5psi of nitrogen

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8
Q

what 2 common scenarios can cause an oil failure control to no longer offer protection

A

crank case pressure not connected and cover removed

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9
Q

Who sets the standards for indoor air Quality

A

ASHREA

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10
Q

What is the purpose of the door switch on a walk in cooler?

A

it shuts off the fans when the door is open to prevent pushing excess cold air out

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11
Q

What device is used to sense temperature on ultra low systems

A

Thermisters

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12
Q

What is the maximum velocity for CONDENSATE lines?

A

150 fpm

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13
Q

What is thermal lag?

A

the time it takes for heat to travel from one side of the substance to the other

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14
Q

What is used to braze copper to steel?

A

Silver Solder

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15
Q

What is the maximum size of Soft Copper allowed for installation

A

1 3/8”

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16
Q

Another Term for Change Over Control

A

Enthalpy Control

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17
Q

Who are Refrigerant releases reported to

A

Alberta Parks and Environment

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18
Q

Convert guage pressure to absolute

A

add 14.7

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19
Q

convert “W.C. to absolute

A

14.7 - (x/2.04)

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20
Q

bypass factor formula

A

(leaving dry bulb temp - coil temp)/(entering dry bulb temp - coil temp)

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21
Q

Heat pump cfm/ton?

A

450

22
Q

A/C cfm/ton

A

400

23
Q

When do you set an EPR

A

During high load conditions

24
Q

When do you set a CPR

A

After a defrost Cycle and adjusted to Compressor FLA

25
Q

What is the biggest factor to consider when setting up an open display case?

A

Do not set it under an air diffuser

26
Q

What is used to clean Condensor Tubes?

A

Nylon Brush

27
Q

What direction must an ecentric bearing ring be turned in order to remove it?

A

In the same direction as the wheel turns during normal operation. (the oval shape is designed to be tightened as the wheel turns, therefor turning in the same direction would loosen it)

28
Q

How is the integrity of an Electronic Air Cleaner (EAC) tested?

A

With a Megger. neither leads are grounded and the ability of the filter relies on the positive plate to keep a Charge during normal operation

29
Q

Replacement gas for R12?

A

R134a

30
Q

What is the result of undersized low Voltage Wiring?

A

Relays and contactors may chatter. (Voltage drop occurs which results in an under voltage to the coil and not enough power to properly pull in the contacts

31
Q

An impedance relay has ____ ohms across the contacts and ____ resistance across the Coil

A

zero and High.

Also known as High impedance relay, or Lock Out Relay.

32
Q

How does a Lock out Relay Function

A

High resistance coil prevents a path for current flow if there is an alternate path with near zero resistance. in the event of safety trip current flows through the LOR and opens the AUX contacts preventing the safety from resetting until manually reset

33
Q

Inlet vane position on a centrifugal system are determined by?

A

Leaving water temperature

34
Q

If the pressure in the condenser is 135 psig and subcooled 10 degrees F, what is the pressure at the outlet of the condenser?

A

135 psig. subcooling does not change Pressure, only temperature

35
Q

% voltage unbalance formula

A

(100 x Max voltage deviation from the AVERAGE voltage) / Average Voltage

36
Q

When converting a system from R12 to R22, what components must be replaced

A

TXV and Filter Drier

37
Q

What refrigerants must be charged as a liquid

A

134a, 404a, R22, and R502

38
Q

What is the easiest way to check the rotation of a scroll compressor?

A

Discharge and Suction Pressures

39
Q

What 4 things do you visually inspect on a Transport Refrigeration system

A

Cleanliness
Oil Leaks
Refrigerant Sight Glass
Oil Level

40
Q

What causes the TXV seat to prematurely wear?

A

Liquid Flashing prior to Valve

41
Q

Where is the King Valve Located

A

Outlet of the Reciever (Queen calls the shots in the Reciever)

42
Q

a perfect vacume is ____ “HG

A

29.4

43
Q

Formula for Compression ratio

A

discharge/suction pressure in ABSOLUTE

44
Q

an oversized evaporator coil will provide a _____ than normal humidity

A

lower

45
Q

if the valve plate gasket on a recip compressor were replaced with one of thicker material, what would happen to compressor efficiency

A

decrease, high positioning of the heads would allow for more refrigerant to be reexpanded before compression can occur.

46
Q

What component Stores refrigerant until it is needed by the evaporator

A

Reciever

47
Q

When should vacume pump oil be replaced?

A

When it can no longer evacuate down to 500 microns (but really after every use no matter how much it was used, moisture in the pump breaks down the gears)

48
Q

How many BTU’s/Cubic FT is natural gas?

A

1000 BTU/Cubic FT

49
Q

recovery cylinders must not be filled to more than ___% of their capacity

A

80%

50
Q

During Defrost, what device MUST be denergized

A

Evaporator Fan

51
Q

formula to convert C to F

A

(1.8 x C) + 32

Refrigeration IP Prep (1 decks)

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