QUIZ 7 Flashcards
(83 cards)
1
Q
Accomplished at temperatures under 842F
A
Soldering
2
Q
Accomplished at temperatures above 842F
A
Brazing
3
Q
Operation of heating and cooling tubing to make it softer
A
Annealing
4
Q
Operation that allows two tubes of Eco diameter to be joined together
A
SWAGING
5
Q
Operation that causes one end of a copper two to expand at an angle for flare nut connection to system
A
Flaring
6
Q
Operation that causes one end of a copper tube to expand at an angle for flare nut connection to system
A
Flaring
7
Q
Removal of burrs and rough edges from tubing
A
Reaming
8
Q
Caused by excessive bending and straightening of tubing
A
Work hardening
9
Q
When soldering, flux should be applied to
A
The male part of the joint only
10
Q
The size indicated for the diameter of copper tubing used for plumbing is the approximate
A
Inside dimension
11
Q
When joining steel pipe, a …….. should be applied to the threads before connecting
A
Pipe dope and Teflon tape
12
Q
The maximum temperature at which soft soldering is done is……
A
842°F
13
Q
If a technician needed 5/8 inch ACR for an installation and was located near only a plumbing supply house what size and type of pipe should he ask for?
A
1/2” ID copper
14
Q
When soldering or brazing the solder is…….
A
Melted by heat from the tubing and fitting
15
Q
For cleaning ACR copper tubing before soldering a material that can be used is……
A
Sand cloth
16
Q
Pipe threads, when they are used on pipe that will contain liquid or vapor under pressure,……..
A
tapered
Generally have a V shape
Should have at least seven perfect threads
17
Q
The size indicated for the diameter of ACR copper tubing is the approximate……
A
Outside diameter
18
Q
Pipe threads are standardized by the A.N.S.A.N.S. Stands for…….
A
American national standard
19
Q
When soldering why should flux be used?
A
It helps solder flow easier
It helps prevent oxidation
It helps keep pipes clean
20
Q
The proper type of flame from an oxy acetylene torch for silver brazing is……
A
Neutral flame
21
Q
Braising is done at……… soldering
A
Higher temperatures than
22
Q
Filler materials used in the high temperature. Connection of copper joints are composed of…..
A
15% to 60% silver
23
Q
Molten solder flows between the two base metals being soldered because…….
A
Of capillary attraction
24
Q
True or false DWV copper stands for drain waste and vent and is also a lightweight copper not typically used in the HVAC industry as far as refrigerant carrying applications are concerned
A
True
25
When installing a refrigeration system that piping should be connected with as few joints as possible
True
26
An air acetylene torch with a twist tip method for mixing the air and acetylene may be used for both low and high temperature soldering
True
27
True or false L type copper is considered medium weight and is used most frequently
True
28
True or false 95/5 tin-antimony Sauter can be used in any part of a refrigeration system
False
29
M is a lightweight copper and is not commonly used in our industry
True
30
K type copper is heavy duty with a thick tubing wall
True
31
True or false When tubing is cut with a tubing cutter, a burr is produced in the process. This slight decrease in the inside diameter of the tube can adversely affect the operation of the system.
True
32
True or false ABS and PVC pipe can be used to carry the new blended refrigerant in low temperature applications
False
33
True or false the end of a piece of a steel pipe is reamed after it is cut with a pipe cutter to make it easier to start the thread die
False
34
True or false, When soldering, the technician should heat the solder with the torch to allow it to melt
False
35
True or false the use of flux is always required when soldering or brazing
False
36
One reason for insulation on a suction line is to help maintain the proper
System superheat
37
The tubing or pipe for natural gas supply to a gas heating unit is…
Steel/ galvanized wrought iron
38
In the thread specification 1/2-14 NPT, the NPT stands for…..
National pipe taper
39
The abbreviation for the plastic pipe used in systems for water and gas supplied lines and irrigation systems is…..
PE/polyethylene
40
The abbreviation for the plastic pipe used in systems for water drains waist drains and low temperature vents is….
ABS
41
The abbreviation for the plastic pipe used in high-pressure systems at low temperature is…..
CPVC/PVC
42
In order to thread steel pipe,…………… must be used to make sure that friction and heat do not damage the pipe and/or cutting di cutting dies
Cutting oil
43
The copper tubing used in the field piping of refrigeration systems is type…..
L/ACR
44
In the thread specification 1/2–14 in PT, the 14 stands for……
Number of threads per inch
45
In the thread specification 1/2–14 NPT, the 1/2 is the…..
Thread diameter
46
Four tools that are needed to properly prepare and thread steel pipe are the………
Die
Reamer
Vice grip
Pipe cutter
47
The abbreviation for the plastic pipe used in hot and cold water supply systems is…
CPVC
48
Map gas has a flame temperature of?
3730°F
49
When making a swage joint, what should the depth of the enlarged portion of the tube be?
The same depth as the size of the pipe +1/8 inch
50
The type of steel pipe thread used primarily in this industry is the “ tapered” thread. Why?
Providing more secure connection and joint for applications that work with high-pressure and high temperature. As pipe is tightened, threads lock in for good connection. Utilize thread sealer.
51
When soldering, what is the flow of molten filler material between the two base metals called?
Capillary attraction.
Filler is melted at temperatures below 842°F when soldering .
Heat base metal and solder melts combining the two base metals .
Filler adheres to all surfaces and forms a good bond .
52
What are two purposes for using insulation on the suction line?
To prevent added heat to the system from ambient air, humidity, this can give false readings for system superheat.
Prevent condensation from pooling in the attic or ceiling spaces that could cause damage to ceiling tiles or unwanted dripping
53
Before you heat a joint, it is a good practice to introduce….. into the system (how and why, finish the paragraph)
Nitrogen
You should have a running constant flow of nitrogen (1-2 psi) when heating/soldering/brazing to limit the amount of carbons that enter the system and oil.
Nitro flow regulator
54
Describe how to prep repairing a leak on a system that still has pressure in it
Pump the system down put all the refrigerant into the receiver or recover if need be.
Flow nitrogen into the open area of the system while you repair leak with 15% silver solder.
After fixing the hole, pressure check and then pull a vacuum before opening system again .
55
What is a compression fitting used for?
And what is a ferrule?
Joining pipes that expand in contract often, a ferrule is the metal ring that goes on the inside of the fitting to provide the seal.
56
If I have some 1/2 “ hard drawn ACR pipe and want to flare the end of the pipe then bend it 90 degrees with my bender what should i do?
Anneal the pipe first so that it will be easier to bend and work with.
1 foot at a time until cherry red, let it cool slowly
Put flare nut on the tube before using the flaring tool to make a flare
As long as pipe is still malleable, use a tube bender to bend your 90° angle
57
Finish the paragraph: the piping system provides…….
A pathway for the refrigerant to flow and change phases as needed to do its specific job in the refrigeration cycle. It connects all components of the system, and also allows a way for oil to return to the compressor from wherever it is in the system.
58
What is pro press? And how would we use it in Hvac?
Pro press is used in water applications. You can do the same thing that soldering/brazing can do in areas that don’t allow heat or open flames. It is more expensive but faster, safer, and has small error margins. We can use it in HVAC and chill water systems, cooling towers, and water cold heat pumps.
59
Name four common heat sources used for soldering and brazing
MAPP
Butane
Propane
Oxy acetylene
Air acetylene
60
Tubing that can be purchased in bundles that have insulated pipes are called? And what are they used for?
Line sets.
These come pre-charged with refrigerant or nitrogen.
When installing a system, these will connect the split units liquid and suction lines, and on startup, the refrigerant will be released into the system.
Also helps keep people from getting burned on discharge .
EEV is on condenser
61
Describe how to set up an oxy acetylene torch set to be ready to braze
Crack lines to clear dirt
Soap joints to check for leaks
Crack acetylene first and then oxygen
5 to 10 ratio with five being acetylene and 10 being oxygen
Make sure to attach pressure regulator to each tank so you are able to monitor and control flow rate
Check hoses for any holes or leaks and make sure torch is attached correctly
When opening tanks use correct tools
Loosen packing gland on the tank to make opening stem a little easier
62
Give me the brazing temp range
1205°F to 1550°F
63
Give me the soldering temp range
361°F to 500°F
64
Bag stands for
B= Brazing
Ag= Silver
65
Oxygen tanks connections are…..treads
Right hand
66
Flux contains………..to…….. water
15% to 35%
67
Anytime copper tubing is heated to a temperature until cherry red, what accumulates inside and outside of the pipe?
Copper oxide scale
68
BCup stands for
Brazing Cup = copper phosphorus
69
Acetylene tanks are……… treads
Left hand
70
Space between fittings and copper pipe where the filler flows is approximately………. Inches.
.0003 in
71
What happens to flux when too much heat is applied when soldering?
The flux will burn out and it will start oxidizing
The solder will not stick, it will bead off
72
After soft soldering, flux should be wiped off because
It is acidic and can cause corrosion
73
An air acetylene torch has a flame temperature of
4200°F
74
What type of solder should be used on a copper suction line to a brass accessory valve?
45% silver with correct flux for dis similar metals
75
What is the recommended type of solder to use on a copper liquid line to a steel filter dryer?
45% silver with correct flux
76
Why is a special Santa cloth used on her medic compressor systems?
The dust particles from sanding could cause it to arc and could be damaging or unsafe
77
Explain why a technician might choose bending instead of soldering or brazing when installing refrigerant lines
Too many heat sensitive components around
Little to no ventilation for fumes
No open flames allowed
One major reason is that joints add resistance/turbulence to flow and can eventually be leak points in the future .
78
When installing refrigerant lines, why is it a good field practice to install the lines so that they are short and straight as possible?
Long lines add to the amount of total charge needed
Ben’s cause restriction to flow and could eventually be leak points
Long lines and bins decrease capacity, pressure and velocity
Pride in your work
Reduces oil traps
79
Explain the difference between wide radius elbows and short radius elbows and their applications
Use long radius elbows, whenever possible to mitigate loss of velocity and refrigerant flow
The more gradual than 90° the less disruption
You short radius elbows, if space is an issue.
80
Can a pro press fitting be used for R290 refrigerant?
Pro press fittings are typically utilized for water piping. If you would like to use a pro press fitting for R290 refrigerant, I would recommend that you verify their compatibility and compliance with safety standards before doing so
81
How would you prep to install a press fitting?
Cut tubing using proper to cutter and deburr as needed
Make sure pipe is perfectly round
Sandpipe to ensure that it is very clean
Open fittings as needed , not too early so dust doesn’t enter and degrade seal integrity
Mark tubing correctly during prep and preassembly
We’re doing the press , hold down button until the tool clutches, and that signifies that it is pressed correctly
If need be, another press can be made for insurance
82
Draw a pipe diagram with an evaporator 25 feet higher than the condenser. Explain your reason for drawing it that way. Include any information you may have learned in class about installing pipe you could apply to this install.
83
Draw a pipe diagram with a condenser 25 feet higher than the evaporator. Explain your reason for drawing it this way.
Include any information you may have learned in class about installing pipe that you could apply to this install
