NFPA Exam CWBSP Topic 4 Question 18 Discussion

Actual exam question for NFPA's CWBSP exam

Question #: 18
Topic #: 4

[All CWBSP Questions]

A 4 in. (102 mm) nominal diameter Schedule 10 sprinkler main is to be supported from the structure utilizing a trapeze

hanger with a span of 8 ft (2.4 m). Using Schedule 40 pipe for the trapeze hanger, what is the minimum diameter pipe

that should be used?

A1.5 in. (40 mm)

B2 in. (50 mm)

C2.5 in. (65 mm)

D3 in. (75 mm)

Show Suggested Answer

Suggested Answer: B

For supporting a 4 in. Schedule 10 sprinkler main with a trapeze hanger spanning 8 ft, a Schedule 40 pipe of at least 2 in. in diameter is typically recommended. This size provides adequate strength for the span and weight of the sprinkler main.

by Glenn at Jul 04, 2025, 04:21 AM

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Paris

41 minutes ago

I'm leaning towards C) 2.5 in. (65 mm) because of the span of the trapeze hanger

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Latricia

7 days ago

I disagree, I believe the correct answer is B) 2 in. (50 mm)

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Jenelle

8 days ago

Hmm, I'm leaning towards C. 2.5 in. (65 mm) just to be on the safe side. Better to have a bit of extra strength than to risk the whole system collapsing, you know?

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Annice

13 days ago

I'm pretty sure it's B. 2 in. (50 mm) seems like the right size for a trapeze hanger supporting a 4 in. (102 mm) main. Anything smaller would be too weak, and anything larger would be overkill.

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Martina

3 days ago

I think you're right, B) 2 in. (50 mm) sounds like the best choice for the trapeze hanger.

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Remona

16 days ago

I think the answer is A) 1.5 in. (40 mm)

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