NFPA CWBSP Exam - Topic 1 Question 19 Discussion

Actual exam question for NFPA's CWBSP exam

Question #: 19
Topic #: 1

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?

A1/32 in. (0.79 mm)

B1/16 in. (1.59 mm)

C1/8 in. (3.17 mm)

D1/4 in. (6.35 mm)

Show Suggested 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 Lovetta at Jul 08, 2025, 09:49 AM

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Malissa

2 months ago

I thought it would be 1/4 in. (6.35 mm) for more safety.

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Kaitlyn

2 months ago

Totally agree with 1/16 in., makes sense!

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Monte

2 months ago

Wait, are we sure about these sizes? Seems off.

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Kimbery

3 months ago

Definitely 1/8 in. (3.17 mm) for better flow.

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Sharika

3 months ago

I think it's 1/16 in. (1.59 mm).

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Teddy

3 months ago

I recall that the hole size is crucial for preventing issues, but I can't remember if it's 1/4 in. or something smaller. This is tough!

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Ashlee

3 months ago

I’m really uncertain about this one. I thought it was 1/32 in., but I might be mixing it up with another topic.

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Isreal

4 months ago

I practiced a similar question, and I feel like 1/8 in. was mentioned as a standard size for check valves. Could that be right?

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Leota

4 months ago

I think the hole size might be 1/16 in., but I’m not entirely sure. I remember something about it being small to prevent backflow.

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Hoa

4 months ago

This seems straightforward. The check valve needs a small hole to allow for some backflow, so I'm going to go with option B, 1/16 in.

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Anthony

4 months ago

I think I've got an approach for this. The size of the hole in the check valve needs to allow for some backflow, but not too much. I'll work through the calculations.

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