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NFPA CWBSP Exam - Topic 3 Question 26 Discussion

For an existing antifreeze system without a backflow prevention device, what size hole is required in the check valve separating the supply and the antifreeze?
A) 1/32 in. (0.79 mm)
B) 1/16 in. (1.59 mm)
C) 1/8 in. (3.17 mm)
D) 1/4 in. (6.35 mm)

NFPA CWBSP Exam - Topic 3 Question 26 Discussion

Actual exam question for NFPA's CWBSP exam
Question #: 26
Topic #: 3
[All CWBSP Questions]

For an existing antifreeze system without a backflow prevention device, what size hole is required in the check valve separating the supply and the antifreeze?

Show Suggested Answer Hide Answer
Suggested Answer: A

If sprinklers are above the level of the water supply to the antifreeze system, a check valve with a 1/32 in. (0.8 mm) hole in the clapper shall be provided in the U-loop.


by Derrick at Mar 08, 2026, 07:39 PM

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Rene
5 hours ago
I think it's B) 1/16 in.
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Helaine
5 days ago
This question is tricky.
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Hailey
11 days ago
Why is there no backflow prevention device in the first place?
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Billy
16 days ago
Totally agree, 1/16 in. is the standard!
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Brynn
2 months ago
Wait, are we sure about these sizes?
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Frank
2 months ago
I thought it was 1/8 in. (3.17 mm).
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Gretchen
2 months ago
It's definitely 1/16 in. (1.59 mm).
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Lisha
3 months ago
Why is there no backflow prevention device? Seems risky!
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Martin
3 months ago
Totally agree with Rebecka!
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Shenika
3 months ago
Wait, are we sure about these sizes?
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Carlton
3 months ago
I thought it was 1/8 in. (3.17 mm).
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Rebecka
3 months ago
It's definitely 1/16 in. (1.59 mm).
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Camellia
3 months ago
I have a feeling that 1/4 in. is too large for a check valve in an antifreeze system, but I can't recall the exact reasoning behind it.
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Ezekiel
4 months ago
I practiced a similar question, and I recall that 1/32 in. was mentioned as a possible option, but I can't remember if it was for this specific scenario.
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Stephanie
4 months ago
I'm not entirely sure, but I feel like 1/16 in. could be the right answer since it's smaller and might prevent backflow better.
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Evangelina
4 months ago
I think the hole size might be 1/8 in. because I remember it being a common size for check valves.
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