What is the purpose of purging with nitrogen while brazing? A) ...

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What is the purpose of purging with nitrogen while brazing?
 
  A) To help the flame burn a little hotter
  B) To check for leaks at the same time you are brazing
  C) To blow the oxides off the walls before it has a chance to firmly adhere
  D) To prevent oxide formation inside the pipes

Question 2

The most efficient operation is achieved with:
 
  A) Thermostatic expansion valves. B) Orifice-type metering devices.
  C) Automatic expansion valves. D) Capillary tubes.

[Tabitha_2016]

Answer to Question 1

D

Answer to Question 2

A

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