REF UNIT 7

Question 1

(7.2) What is steel-wrought pipe used for?

Answer 1

gas lines and steam heating

Question 2

(7.2) How is copper piping categorized?

Answer 2

K, L, M, DWV [K being heavy duty, DWV is used for drainage and waste(not typically used in our industry)].

Question 3

(7.2) What is copper tubing used for refrigeration and air conditioning called?

Answer 3

ACR tubing

Question 4

(7.2) how is ACR sized?

Answer 4

by outside diameter

Question 5

(7.2) How is plumbing and heating tubing sized?

Answer 5

by inside diameter

Question 6

(7.2) Define annealing

Answer 6

the process of heating and slowly cooling a metal in order to strengthen it (specifically copper tubing).

Question 7

(7.4) What do line sets come with?

Answer 7

liquid line and vapor line

Question 8

(7.6) What are the 2 tools used in bending tubing?

Answer 8

tube bending springs and lever-type tube benders

Question 9

(7.7) What is the soldering temperature range?

Answer 9

361F to 500F

Question 10

(7.7) What is the brazing temperature range?

Answer 10

1205F to 1550F

Question 11

(7.7) What are the two common filler metals used in soldering?

Answer 11

1. 50/50 (50% tin, 50% lead), used for moderate pressures and temperatures.
2. 95/5 (95% in, 5% antimony), used for high pressure water lines.

Question 12

(7.7) Why must brazing be done in some applications?

Answer 12

because of the filler material

Question 13

(7.7) What 2 filler metals can be used in brazing?

Answer 13

a silver alloy or a copper-phosphorous alloy

Question 14

(7.8) What are the 5 common torch types found in the industry?

Answer 14

propane, butane, oxyacetylene, MAPP gas, and air-acetylene.

Question 15

(7.8) What torch produces the hottest flame?

Answer 15

Oxyacetylene torch

Question 16

(7.9) What does flux do in brazing and soldering?

Answer 16

prevents oxidization and facilitates filler material flow.

Question 17

(7.9) Where do you apply flux?

Answer 17

only on the male part of the connection

Question 18

(7.9) Why should a phosphorous filler material never be used when brazing with steel?

Answer 18

because phosphorous and steel produce phosphides, which are easily cracked.

Question 19

(7.9) How do you displace oxygen in pipe that is being brazed?

Answer 19

pressurize system with 1 to 2 psi(g) of nitrogen.

Question 20

(7.16) How is steel pipe specified?

Answer 20

ID for pipes less than 12 inches diameter, OD for pipes more than 12 inches diameter.

Question 21

(7.16) What are the only type of threads used on steel pipe in the HVAC industry?

Answer 21

tapered threads

Question 22

(7.16) How is pipe threading specified?

Answer 22

thread diameter, number of threads per inch, National pipe taper (1/2-14 NPT).

Question 23

(7.17) What does pipe dope do?

Answer 23

helps seal pipes.

Question 24

(7.18) What is ABS piping for?

Answer 24

drainage, waste, venting

Question 25

(7.18) What is polyethylene (PE) piping for?

Answer 25

cold water, gas, irrigation (only low pressure).

Question 26

(7.18) What is PVC piping for?

Answer 26

high pressure, low temperature applications (like gas, waste).

Question 27

(7.18) What is CPVC piping for?

Answer 27

like PVC but can be used with high temperatures.