A plumbing rough-in inspection checks fixture trap seals. What common water-seal range is used for fixture traps?
Correct Answer
D) 2 to 4 in.
Fixture trap seals are commonly required to be at least 2 in. and not more than 4 in. Other choices are too shallow to protect the trap seal or too deep for the standard range.
Why This Is the Correct Answer
Fixture trap seals are commonly required to be at least 2 in. and not more than 4 in. Other choices are too shallow to protect the trap seal or too deep for the standard range.
Why the Other Options Are Wrong
Option A: 1/2 to 1 in.
The trap in A is 1/2 to 1 in. That selection is wrong because 1/2 to 1 in. is a different published number than the cited Trap seal value; Fixture trap seal depth supports 2 to 4 in.; Fixture trap seals are commonly 2 to 4 in. deep.
Option B: 1 to 2 in.
Choice B gives 1 to 2 in. Its specific error: 1 to 2 in. is a different published number than the cited Trap seal value; Fixture trap seal depth supports 2 to 4 in. The accepted answer is 2 to 4 in.
Option C: 4 to 8 in.
Choice C (4 to 8 in.) is rejected because 4 to 8 in. is a different published number than the cited Trap seal value; Fixture trap seal depth supports 2 to 4 in. The cited answer is 2 to 4 in.
Memory Technique
Make trap seal a tabbed card: cite the exact condition, then choose 2 to 4 in.
Reference Hint
Open Pipe and Excavation Contracting, 2011; use the index entry or section for "Fixture trap seal depth" to confirm that Fixture trap seals are commonly required to be at least 2 in.
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