NFPA CWBSP Exam - Topic 2 Question 7 Discussion

Actual exam question for NFPA's CWBSP exam

Question #: 7
Topic #: 2

To what exponent is the pipe diameter raised when calculating friction loss through a pipe with the Hazen-Williams formula?

A1.85

B2.31

C4.52

D4.87

Show Suggested Answer

Suggested Answer: D

You can see in the above equation that if Q is raised to the power of 1.85 in the above equation, this has the effect if the flow is doubled and all other factors remain constant, the friction loss would increase by almost four times. If the flow were to triple, the friction loss would almost be nine times greater. You can also see that the pipe diameter D is raised to the power of 4.87 and is in the denominator on the right-hand side of the equation. Therefore any increase in the pipe size will reduce the friction loss if all other factors remain the same. If the diameters double, the friction loss will be reduced by almost a factor of 1/32 likewise, if the pipe diameter is tripled, The friction loss would be reduced to about 1/243 of its original value.

https://canutesoft.com/hydraulic-calculation-for-fire-protection-engineers/the-hazen-williams-formula-for-use-in-fire-sprinkler-systems#:~:text=You%20can%20also%20see%20that,other%20factors%20remain%20the%20same.

by Sommer at Dec 10, 2024, 08:50 PM

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Cheryl

3 months ago

I always get confused with these exponents, but I trust 1.85.

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Quentin

3 months ago

Definitely not 4.52, that's way off!

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Pedro

3 months ago

Wait, is it really 1.85? I thought it was higher.

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Tamala

4 months ago

Totally agree, 1.85 is the right one.

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Anika

4 months ago

It's 1.85 for the Hazen-Williams formula!

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Amber

4 months ago

I thought it was 4.52, but now I’m second-guessing myself. This is tricky!

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Brynn

4 months ago

I’m pretty confident it’s 4.87, but I could be confusing it with another formula.

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Hayley

4 months ago

I remember practicing a similar question, and I feel like it was 1.85. I hope I’m not mixing it up!

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Alaine

5 months ago

I think the exponent for the pipe diameter in the Hazen-Williams formula is 2.31, but I'm not completely sure.

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Kanisha

5 months ago

I'm a bit confused on this one. I'll have to think it through step-by-step to make sure I get the right exponent.

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Paris

5 months ago

The Hazen-WilElmiras formula is one I've practiced a lot, so I'm confident the answer is 1.85. I'll mark A.

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Elmira

5 months ago

Hmm, I'm a little unsure about this one. I'll need to double-check the formula to make sure I have the right exponent.

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Dominque

5 months ago

I'm pretty sure the Hazen-Williams formula uses the pipe diameter raised to the 1.85 power, so I'll go with A.

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Evan

1 year ago

Ah, the age-old question of pipe friction. I'm going with C, 4.52 - it just rolls off the tongue, you know?

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Stefanie

1 year ago

I'm with you on this one, C just sounds right. 4.52 it is!

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Pok

1 year ago

I'm not sure, but I remember my professor mentioning it's raised to the power of 2.31. So maybe B?

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Johnetta

1 year ago

I think it's actually D, 4.87. That's what I learned in my fluid mechanics class.

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Willard

1 year ago

Oh, I see. Thanks for clarifying that. I'll remember that for the exam.

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Isadora

1 year ago

But the Hazen-Williams formula actually raises it to the power of 4.52.

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Frederic

1 year ago

2.31? Really? That seems a bit odd for the Hazen-Williams formula. I'll have to double-check my notes on that one.

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Denise

1 year ago

Let's look it up to be sure. It's important to get the calculations right.

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Merlyn

1 year ago

I'm pretty sure it's 4.52, but now I'm second-guessing myself.

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Verda

1 year ago

Are you sure about that? I remember learning it was raised to the power of 1.85.

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Shayne

1 year ago

I think it's actually raised to the power of 4.87.

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Willard

1 year ago

I disagree, I believe it's raised to the power of 1.85.

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Clarence

1 year ago

Hmm, 4.87 sounds about right. Gotta love those empirical pipe flow equations, am I right?

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Felicitas

1 year ago

Definitely! Empirical equations make life easier when calculating friction loss in pipes.

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Naomi

1 year ago

Yeah, 4.87 is the correct exponent for the Hazen-Williams formula.

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Dominic

1 year ago

Wait, isn't it 4.52? I remember that from my fluid dynamics class, but I could be wrong...

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Alline

1 year ago

I think you might be mistaken, it's actually 4.52.

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Thora

1 year ago

I remember learning that it's 1.85.

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Dean

1 year ago

No, I'm pretty sure it's 2.31.

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Wilbert

1 year ago

I think it's actually raised to the power of 4.87.

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Lilli

1 year ago

I'm pretty sure it's 1.85, that's the classic Hazen-Williams exponent we all know and love.

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Danica

1 year ago

Correct, it's always good to remember the classic values.

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Chantell

1 year ago

So, the answer is A) 1.85 then.

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Jerrod

1 year ago

Yeah, that's the exponent used in the Hazen-Williams formula.

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Gracia

1 year ago

I think you're right, it is 1.85.

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Isadora

1 year ago

I think it's raised to the power of 4.87.

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