Discuss NFPA CFPS Exam Topic 3 Question 19

Typical fire pump drivers reach maximum brake horsepower between

A65-85% of rated capacity.

B90-100% of rated capacity.

C110-125% of rated capacity.

D140-170% of rated capacity.

Suggested Answer: D

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Typical fire pump drivers reach maximum brake horsepower (BHP) between 140% and 170% of rated capacity, depending on the type and size of the pump. This means that the driver must be able to provide enough power to operate the pump at its peak efficiency point, which is usually beyond the rated capacity. The rated capacity is the flow rate at which the pump is designed to deliver a certain pressure, as specified by NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection. The maximum BHP is the highest power output required by the pump at any point on its performance curve. The driver must be sized to match the maximum BHP of the pump, with some allowance for service factor and safety margin. Reference: Understanding the Basics of Fire Pumps | Pumps & Systems; How are Engines and Motors Sized for Fire Pumps?; NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection, 2023 Edition, Chapter 4, Section 4.7.

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26 comments · newest first

Antonio 5 months ago

C seems too high. B is the sweet spot for reliability.

Leslee 5 months ago

I’m leaning towards A. It feels safer at that range.

Harley 6 months ago

I agree, B makes sense. High efficiency.

Myra 6 months ago

I think it's B, 90-100%. Seems standard.

Meghan 6 months ago

Interesting, I didn’t know it was that low.

Matilda 6 months ago

I thought it was B) 90-100%. Guess I was wrong!

Paulina 6 months ago

Wait, 110-125%? That seems way too high!

Brice 6 months ago

Totally agree, that’s what I’ve always heard!

Dominga 7 months ago

A) 65-85% is the sweet spot for fire pumps.

Minna 7 months ago

B) 90-100% of rated capacity. Anything higher would probably blow the pump right off the truck!

Cherrie 7 months ago

Hmm, I'm not sure if fire pumps even have a "brake horsepower" rating. This question seems a bit fishy to me.

Annamae 8 months ago

C) 110-125% of rated capacity? That's way too high for a fire pump driver. I'm confident B) 90-100% is the right answer.

Malcom 8 months ago

D) 140-170% of rated capacity seems a bit excessive. I'm going with B) 90-100% as the correct answer.

Skye 8 months ago

I think the answer is B) 90-100% of rated capacity. That's the typical operating range for fire pump drivers.

Julieta 8 months ago

I’m leaning towards option B, but I could be mixing it up with something else we studied about efficiency ratings.

Ruth 8 months ago

I have a vague recollection that it could be higher, like 110-125%, but that seems a bit off for fire pumps.

German 8 months ago

I'm not entirely sure, but I feel like we practiced a question that mentioned 65-85% being typical for other types of pumps.

Jess 9 months ago

I think I remember something about fire pump drivers reaching max horsepower closer to their rated capacity, maybe around 90-100%?

Ryann 9 months ago

Alright, I've got a strategy here. I'm going to think through the physics of how fire pump drivers operate and use that to narrow down the options. Gotta love applying that textbook knowledge!

Terrilyn 9 months ago

I'm a bit unsure about this one. Fire pump drivers are not something I'm super familiar with. I'll have to make an educated guess and hope for the best.

Malcom 9 months ago

Ah, I remember learning about this in my fire protection systems class. I think the key is understanding where fire pumps typically operate at maximum efficiency. Time to put that knowledge to use!

Carmen 9 months ago

Okay, let me see. I know fire pumps need to deliver a lot of power, so I'm guessing it's probably in the higher range of their capacity. I'll eliminate the lower options and focus on C and D.

Shay 10 months ago

Hmm, this seems like a tricky one. I'll need to think through the typical operating characteristics of fire pump drivers to figure this out.

Sabra 3 months ago

↳ replying to Shay

What about C? It could be possible too.

Odette 4 months ago

↳ replying to Shay

I disagree, I lean towards A. It's more common.

Lonna 5 months ago

↳ replying to Shay

I think it's B. They usually operate at high capacity.

NFPA CFPS Exam - Topic 3 Question 19 Discussion