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Fixtures materials practice questions

25 questions from the plumbing fundamentals practice test.

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Fixtures materials practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

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Sample questions

Under the Safe Drinking Water Act, solder and flux used on potable water piping may contain no more than what percentage of lead?

  1. 0.25 percent
  2. 0.2 percent
  3. 8 percent
  4. 50 percent
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B. 0.2 percent

The Act defines lead free for solder and flux as not more than 0.2 percent lead. 0.25 percent is the separate limit for wetted surfaces of pipe, fittings and fixtures, and 8 percent was the old limit for pipe and fittings before 2014.

Reference: Safe Drinking Water Act, Section 1417 (42 U.S.C. 300g-6)

What does flux do in a soldered copper joint?

  1. It melts and fills the gap between the tube and the fitting cup in place of solder
  2. It cools the fitting quickly so the solder sets before it can run out of the joint
  3. It keeps the cleaned surfaces from oxidizing as they are heated so solder can bond
  4. It lowers the temperature at which the copper tube itself begins to melt
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C. It keeps the cleaned surfaces from oxidizing as they are heated so solder can bond

Flux dissolves light oxide and shields the bright metal from the air while it is heated, which lets molten solder wet the copper and be drawn into the joint by capillary action. Flux is not a filler; too much of it left inside the tube causes corrosion.

Reference: Copper Development Association, Copper Tube Handbook (soldered joints); ASTM B828

What separates brazing from soldering?

  1. Brazing filler melts above 840 degrees F
  2. Brazing filler metal contains more lead
  3. Brazing melts the edges of the base metal
  4. Brazing is done without cleaning the joint
Show the answer

A. Brazing filler melts above 840 degrees F

By definition, soldering uses filler metals that melt below 840 degrees F and brazing uses fillers that melt above it, while the base metal does not melt in either process. Melting the base metal is welding.

Reference: American Welding Society definitions; Copper Development Association, Copper Tube Handbook

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