Discuss NFPA CWBSP Exam Topic 3 Question 33

What is the thrust force on an 8 in. (205 mm) ductile iron 90 bend with a water test pressure of 200 psi (13.8 bar)?

A5,288 lb (2,400 kg)

B9,097 lb (4,126 kg)

C13,685 lb (6,207 kg)

D18,194 lb (8,253 kg)

Suggested Answer: A

The thrust force on a bend in a piping system can be calculated based on the water pressure and the size of the pipe. An 8-inch ductile iron bend at 200 psi would generate significant force, but among the given options, 5,288 lb is the most plausible based on typical hydraulic calculations.

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21 comments · newest first

Pauline 2 days ago

I remember the formula. It’s definitely A for me.

Meghan 7 days ago

I feel overwhelmed. Pressure calculations are tough!

Ligia 12 days ago

I think it’s C. The calculations seem to point there.

Freeman 17 days ago

This question is tricky. I’m leaning towards option B.

Annmarie 23 days ago

Yeah, pressure affects the thrust force significantly.

Linn 28 days ago

I think A is definitely too low. The pressure is high!

Latosha 1 month ago

B could be a good middle ground, but I still favor C.

Pura 1 month ago

D feels excessive. I doubt it’s that high.

Melita 1 month ago

I agree with Evan. C makes sense with the calculations.

Evan 2 months ago

I’m leaning towards C. It seems reasonable for a 90 bend.

Chaya 2 months ago

I feel like A is too low for that pressure.

Annmarie 2 months ago

This question is tricky. I think it's about understanding pressure and force.

Selma 2 months ago

13,685 lb? That seems way too high!

Benton 2 months ago

I agree with Dexter, 9,097 lb seems right.

Ciara 2 months ago

Wait, are we sure about those numbers? Sounds off to me.

Amber 3 months ago

I think it's actually 5,288 lb.

Dexter 3 months ago

The thrust force is definitely around 9,097 lb!

Marci 3 months ago

I practiced a question like this last week, and I think I got a different answer, but I can't remember the details. I should have reviewed more!

Hyun 3 months ago

I feel like the answer is closer to the higher end of the options, maybe around 13,685 lb, but I need to double-check my calculations.

Gerardo 3 months ago

I think the thrust force depends on the pressure and the area of the bend, but I'm not sure how to calculate the area for a 90 bend specifically.

Lorrine 4 months ago

I remember we did a similar problem in class about calculating thrust forces, but I can't recall the exact formula we used.

NFPA CWBSP Exam - Topic 3 Question 33 Discussion