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4th Year > Split Systems > Flashcards

Split Systems Flashcards

(68 cards)

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1
Q

What does a manifold set and pressure gauges do ?

A

Reads pressures
Boiling points
And saturation points

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2
Q

If valves are closed on gauges and we connect them to a live system will we read pressures ?

A

Yes

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3
Q

If you go from one refrigerant to another what should you do with your gauges ?

A

Clean them out (purge with nitrogen)

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4
Q

What colour is the low side and high side of gauges ?

A

Low =blue
High =red

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5
Q

The center hose (manifold gauge bank ) is ussally coloured coded what colour ?

A

Yellow

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6
Q

The center hose (manifold gauge bank ) is used for what ?

A

Adding and removing refrigerant

Allows you to pull a vacuum as well

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7
Q

If a gauge has a black line what is it used for ?

A

Adding or removing refrigerant

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8
Q

Three styles of pressure gauges used in the refrigeration field ?

A

High pressure
Vacuum
Compound

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9
Q

Gauges should never be subjected to more than ____% of Thier full scale range on the gauge face. And why

A

75%

Saftey reasons and also for accuracy of gauge

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10
Q

Low side (blue) gauge is a compound gauge designed to provide both ______ readings and ________ readings

A

Pressure readinngs = 0-250psig

Vacuum readings =0 to 30” Hg

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11
Q

High side gauge is graduated in ___ pound increments from 0-500psi. The high side gauge is designed to read ?

A

10 pound increments

Read pressures only above atmospheric

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12
Q

Hoses are constructed to withstand pressures in excess of _____ psi and burst pressure of _______psi for r22.

A

500
2000

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13
Q

Where can you find how much pressure a hose can withstand ?

A

On the hose

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14
Q

Hoses for r-410a are constructed to withstand ______psi with a burst pressure of ____psi

A

800
4000

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15
Q

The hose with a 45 connection connects to what ?

A

Service valve

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16
Q

Other side of hose that is straight connection connects to ?

A

The manifold

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17
Q

3 ways of identifying refrigerants?

A

Labels
Service fittings
Using a refrigerant identifier

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18
Q

Many refrigerants are colourless and odourless. True or false

A

True

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19
Q

How do we know what refrigerant is inside a system ?

Ait

A

Rateing plate

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20
Q

4 types of refrigerant leak detectors ?

A

Ion source detection
Thermistor type
Halogen type
Ultrasonic type

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21
Q

How do ultra sonic leak detectors work ?

A

Pick up sounds we can’t hear

The sounds occour when there is a leak in system and refrigerator air is being forced through

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22
Q

Benefits of ultrasonic leak detectors ?

A

Can use in a positive and negative pressure

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23
Q

What is a recovery unit used for ?

A

Remove refrigerant from the system and store it in an approved external container without necessarily filtering or processing it in any way

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24
Q

Do u need to remove refrigerant to make repairs to the system ?

A

Yes

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25
U can fill a a storage cylinder over 80%. True or false ?
False only 80%
26
How do recycling units work ?
Same manner as the recovery units but take it one step further by adding filters and oil separators that remove any compressor oil moisture and some contaminates from the refrigerant
27
What colour is r-22 cylinders ?
Light green
28
What colour is r-410a ?
Rose
29
Storage cylinders are used for ?
Recovery recycling and reclaiming of refrigerant
30
Storage cylinders range from ____lbs to ____lb and must be ______________ approved.
20lbs 100lbs Department of transportation approved
31
Vacuum pumps are used to ?
Evacuate the closed refrigeration system into a deep vacuum. Process is necessary to remove any gas or moisture that may be in the system
32
Why are two stage rotary vacuum pumps used ?
They are capable of reducing the pressure in a leak free system to 0.1 microns
33
A two stage rotary vacuum pump is usually faster. True or false ?
True
34
Make sure there’s no positive charge on nitrogen in the system when vacuuming. True or false ?
True
35
When should you replace the oil in a vacuum ?
Replace the oil after each use
36
Without a vacuum gauge (micron gauge) you take the risk of what?
Not dehydrating the system properly
37
A thermistor vacuum gauge (micron gauge) contains 2 elements what are they ?
Heater (filament ) Thermocouple junction that contacts the filament
38
What do charging scales do ?
Let’s u know how much refrigerant is used or in a system Can use when adding or removing refrigerant
39
Nitrogen is used in two ways what are they ?
Small amount used to Flow through copper when brazing to prevent the copper from forming oxides on inner surface Used to pressurize the system to check for leaks
40
Before you braze any pipe , it is important to fit the pipe and clean it to ensure?
Job is done correctly
41
Why do we get rid of the burr after cutting copper ?
The burr decreases the diameter of pipe
42
The rod that is normally used for brazing cooling lines is made of an alloy containing ____ to ______% silver and is commonly known as ______
5-15% silver Silfos
43
Which holds the most pressure weld joint braze or solder ?
Weld then braze then solder
44
Why do we try to avoid solder for refrigeration lines in a building ?
If a building burns solder will melt and allow refrigerant to leak
45
R-410a systems operate at a pressure _____times that of similar pressures using r22.
1.6 times out of
46
When a valve is front seated its is ?
Closed
47
When a valve is back seated its is ?
Open
48
Where do u Hooke up the low pressure gauge (blue gauge ?
Low pressure side
49
Where do you hook up the high pressure gauge (red gauge)
High pressure side of system
50
Where is the center hose connected to ?
Inlet port on recovery unit
51
It is considered good practice to use the shortest hose possible. True or false ?
True
52
How do u remove shrader valves ?
Special tool
53
If a system components show evidence of icing during the recovery process , the components can be heated gently to speed up the flow of refrigerant. What can you use to do so and what are not allowed to use
Heat gun or hot air blow dryer Don’t use open flame
54
What does moisture in refrigeration do ?
Damages the compressor
55
To be certain that as much moisture and non condensate gases as possible are removed, a vacuum of ________ microns or less must be obtained.
500 microns
56
If gauge rises slowly to 1500 microns this indicates what ?
Moisture in the system
57
If gauge steadily rises to atmospheric pressure it means what ?
Leak in the line and must be located and repaired
58
Most new split systems come with a factor charge of refrigerant. This charge is adequate for ________ unit with a matched _______ ________ and __ to ___ feet of ____ _____
Condenser unit Evap coil 15 to 20 feet Line set
59
What is manufactures recommended air flow across the evaporator coil ?
Between 400CFM to 425CFM per ton of cooling
60
Liquid recovery is the fastest way to recover refrigerant true or false ? Ait
True
61
For adding refrigerant the fastest way of doing it is ? Ait
High pressure liquid to low pressure vapour side
62
Pulling recovery and you know there’s a leak in the system you go to ??? Positive Negative 0 degrees Ait
0 degress
63
If you have a thermal expansion valve u can check for proper ________
Sub cooling
64
If you have orfice or capillary tubes systems u can check for ?
Superheat
65
The measured super heat should be within +\- ___ of the super heat found on the table
+\- 2 degrees Fahrenheit
66
Adjust charge based on superheat on systems with thermal expansion valves. True or fakse
False don’t adjust the charge U can check superheat to see if txv is working properly
67
It is much easier to remove refrigerant than to add it true or false ?
False easier to add not remove
68
Watch the vacuum gauge for ____ to ____ minutes to see if it rises
5 to 20 minutes

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