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NFPA Exam CWBSP Topic 2 Question 7 Discussion

Actual exam question for NFPA's CWBSP exam
Question #: 7
Topic #: 2
[All CWBSP Questions]

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

Show Suggested Answer Hide 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.


Contribute your Thoughts:

Evan
1 months 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
20 days ago
I'm with you on this one, C just sounds right. 4.52 it is!
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Pok
22 days 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
27 days ago
I think it's actually D, 4.87. That's what I learned in my fluid mechanics class.
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Willard
2 months ago
Oh, I see. Thanks for clarifying that. I'll remember that for the exam.
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Isadora
2 months ago
But the Hazen-Williams formula actually raises it to the power of 4.52.
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Frederic
2 months 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 months ago
Let's look it up to be sure. It's important to get the calculations right.
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Merlyn
1 months ago
I'm pretty sure it's 4.52, but now I'm second-guessing myself.
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Verda
2 months ago
Are you sure about that? I remember learning it was raised to the power of 1.85.
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Shayne
2 months ago
I think it's actually raised to the power of 4.87.
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Willard
2 months ago
I disagree, I believe it's raised to the power of 1.85.
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Clarence
2 months ago
Hmm, 4.87 sounds about right. Gotta love those empirical pipe flow equations, am I right?
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Felicitas
2 months ago
Definitely! Empirical equations make life easier when calculating friction loss in pipes.
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Naomi
2 months ago
Yeah, 4.87 is the correct exponent for the Hazen-Williams formula.
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Dominic
2 months 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 months ago
I think you might be mistaken, it's actually 4.52.
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Thora
2 months ago
I remember learning that it's 1.85.
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Dean
2 months ago
No, I'm pretty sure it's 2.31.
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Wilbert
2 months ago
I think it's actually raised to the power of 4.87.
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Lilli
3 months 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
2 months ago
Correct, it's always good to remember the classic values.
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Chantell
2 months ago
So, the answer is A) 1.85 then.
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Jerrod
2 months ago
Yeah, that's the exponent used in the Hazen-Williams formula.
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Gracia
2 months ago
I think you're right, it is 1.85.
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Isadora
3 months ago
I think it's raised to the power of 4.87.
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