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Journeyman Plumber Exam

Drainage: practice questions

Our Journeyman Plumber bank has 24 questions on this topic. Here are 5 of them with answers; the full mock exam draws from every topic, like the real one.

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Question 1

What is a 'trap arm'?

  1. The vent through the roof
  2. The fixture tailpiece
  3. The section of drain between a trap's outlet and the vent connection
  4. The pipe above the trap
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C. The section of drain between a trap's outlet and the vent connection — Codes limit trap arm length by pipe size.

Question 2

What is a building drain?

  1. A vent stack
  2. A floor drain
  3. The lowest horizontal piping inside the building that receives the discharge from soil and waste stacks
  4. The pipe from the building to the public sewer
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C. The lowest horizontal piping inside the building that receives the discharge from soil and waste stacks — The building sewer starts outside the building wall.

Question 3

What is a 'combination waste and vent system'?

  1. A standard vent stack
  2. A sewer pump system
  3. A system using oversized horizontal drains that also serve as vents, permitted in limited cases
  4. A system with no vents at all ever
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C. A system using oversized horizontal drains that also serve as vents, permitted in limited cases — Used in some commercial floor drain designs.

Question 4

Why can't a drain pipe be reduced in size in the direction of flow?

  1. It's too expensive
  2. It looks bad
  3. Smaller pipes downstream would restrict flow and cause clogs
  4. Codes require larger downstream pipes for gas lines only, not for drains
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C. Smaller pipes downstream would restrict flow and cause clogs — Drain size must stay the same or increase.

Question 5

What is a 'soil stack'?

  1. A vertical pipe that carries waste from water closets (and similar fixtures)
  2. A vent pipe
  3. A pipe carrying only clear water
  4. A rainwater leader
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A. A vertical pipe that carries waste from water closets (and similar fixtures) — Waste stacks carry waste without fecal matter.

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