Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

2nd Year Refrigeration > Metering Devices, Application And Troubleshooting > Flashcards

Metering Devices, Application And Troubleshooting Flashcards

1
Q

What controls low side float

A

Liquid level in the low side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What controls high side float

A

Liquid level in high side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What controls Capillary tube

A

Pressure difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What controls automatic expansion valve

A

Evaporator pressure plus spring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What controls thermostatic expansion valve

A

Superheat at the outlet of the evaporator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

TXV pressure formula

A

Bulb pressure = spring pressure + evaporator pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does a low side float achieve

A

Minimum level of liquid in a flooded evaporator. Stops when:

  • system equalizes or
  • liquid levels raise enough to lift float and shut off inlet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does a high side float look to achieve

A

Liquid levels in highside of system. Opens outlet valve to evaporator as liquid levels increase in high side.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does a capillary tube look to achieve

A

Pressure difference between high side and low side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does an automatic expansion valve look to achieve

A

Maintains constant pressure in evaporator by use of spring pressure + evaporator pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does a Thermostatic Expansion Valve (TXV) look to achieve

A

Maintains a constant superheat at the evaporator outlet. Bulb pressure = spring pressure + suction pressure (evaporator)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where are low side floats used

A
  • commercial
  • industrial
  • low temperature applications
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where are high side floats used

A
  • domestic

- industrial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where are capillary tube valves used

A
  • domestic self contained units
  • package equipment
  • LOW TORQUE MOTORS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where are Automatic Expansion Valves used

A
  • Domestic

- brine systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where are TXV’s used

A
  • Commercial air conditioners

- industrial air conditioners

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Low side float adaptability to varying loads

A

Excellent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

High side float adaptability to varying loads

A

Good

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Capillary tube adaptability to varying loads

A

Fair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Automatic expansion valve adaptability to varying loads

A

Poor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

TXV adaptability to varying loads

A

Excellent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which two metering controls require a critical charge

A

High side float and capillary tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Can a low side float system store refrigerant

Re word question

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What device must a capillary tube system have

A

Accumulator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What device muse a capillary tube system NOT have

A

Reciever

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Low side float symptoms of overcharge

A

Excessive head pressure

Float remains high and allows minimal liquid refrigerant to flow causing high head pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Low side float symptom of undercharge

A

High suction pressure

Low charge causes float to drop allowing high pressure liquid refrigerant to flow freely

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

High side float symptoms of overcharge

A

Flood back in suction line

(Excess liquid refrigerant flows into float tank causing outlet to fully open allowing uncontrolled amounts of liquid refrigerant to flow to suction side)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

High side float symptoms of undercharge

A

Low back pressure

(Low levels of liquid refrigerant cause the float to drop forcing the outlet to choke the amount of liquid refrigerant flowing to suction side)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Capillary tube system symptom of overcharge

A

Floodback in suction line

Pressure differential is still maintained however high pressure liquid refrigerant is forced through

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Capillary tube system symptoms of undercharge

A

Low head and suction pressures

Tube acts oversized and system equalizes

32
Q

Automatic expansion valve system symptoms of overcharge

A

High head pressure

Fully compressed spring will still only allow a certain amount of refrigerant through

33
Q

Automatic expansion valve system symptom of undercharge

A

Low head pressure

34
Q

TXV system symptom of overcharge

A

High head pressure

Bulb = spring + suction pressure

35
Q

TXV system symptom of undercharge

A

Low head pressure and high superheat

Bulb = spring + suction pressure
If suction pressure goes down, valve opens more than usual

36
Q

Which 3 valves are adjustable in the field

A
  • automatic expansion valve
  • TXV
  • hand expansion valve
37
Q

Which two metering devices are used on multiple systems

A

Low side float and TXV

38
Q

Do liquid and cross charges have a MOP

A

No

39
Q

Do gas and gas cross charges have a MOP

A

Yes

40
Q

Where does migration occur

A

At the coldest spot

41
Q

What happens to a TXV if the bulb were to rupture

A

The valve would shut

Bulb pressure = spring pressure + superheat

42
Q

What is likely cause of cap tube plugging in the first 6”

A

Desiccant (filter drier break down)

43
Q

What is likely cause of cap tube plugging in last 6”

A

Moisture or wax

44
Q

What does an under capacity valve result in

A

Starving evaporator

45
Q

What does over capacity valve result in

A

Hunting

46
Q

Where is the valve screen located

A

Inlet of valve

47
Q

What is the minimum setting of superheat on an electrical expansion valve

A

O F degrees and up

48
Q

What is the proper way to test a TXV seat

A

Pressurize the outlet and cool the bulb

49
Q

What type of metering device is used for low torque starting

A

Cap tube

50
Q

What device must be used with a cap tube system

A

Accumulator

51
Q

What does a TEV maintain

A

Constant superheat in the evaporator

52
Q

What is the result of an overcharged AEV system

A

High head pressure

53
Q

What happens to sub cooling and average if cap tube is plugged

A

Subcooling goes up

Amp draw goes down

54
Q

What is the purpose of a double diaphragm TXV

A

Limit suction pressure during high load conditions

55
Q

Rating of TXV

A

Measured in tons

56
Q

Function of CPR or CRO and how does it operate

A

Closes on rise of outlet, maintains max compressor pressure (safety)

57
Q

Purpose and function of EPR

A

“Hold back valve” maintains pressure in evaporator. Closes on rise of inlet pressure

58
Q

Purpose of ORD

A

Open on rise of differential, maintains 2F degree differential. Used in on condensing unit

59
Q

Function of ORI

A

Open on rise of inlet. Like EPR, minimum pressure to receiver

60
Q

Function of headmaster

A

(ORI+ORD) maintains head pressure, bypasses condensing unit in cold atmospheric conditions (>70F)

61
Q

Function of reversing valve

A

Redirects lines for building heat (evaporator and condensing unit trade places)

62
Q

Purpose of DPR

A

Discharge pressure regulator. Max head pressure to Condensing unit. Used with hot gas bypas

63
Q

3 types of check valves

A

Ball
Gate
Spring

64
Q

Sizing of receiver

A

10% full at any time.

Must carry 125% of system capacity

65
Q

Another name for EPR

A

2 temperature valve or “Hold back valve”

66
Q

3 wire oil control

A

Line duty

67
Q

4 wire oil control

A

Pilot duty

68
Q

Sizing refrigerant drop in

A

Pressure at 0F, and at 100F if difference between refrigerants is greater than 50 then you can’t drop in

69
Q

3 types of filter driers

A

Loose full
Compressed bead
Solid core

70
Q

Evaporator CFM/ ton for cooling and heating

A

400CFM/ton cooling

450CFM/ ton heating

71
Q

Type of copper used in general

A

Type K and L

72
Q

Type of metal for ammonia system

A

Black iron or stainless steel
No yellow metals
Valve classified type A or D

73
Q

Bracing temp

A

840 - 1985F

74
Q

Purpose of discharge outlet on ammonia TXV

A

Reduce wire draw

75
Q

TQ ques

Solenoid valve construction

A

Soft iron Core and copper

76
Q

Cap tube length

A

6-18”

2nd Year Refrigeration (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions