For a horizontal split case fire pump, 10 pipe diameters of straight pipe is to be provided for the suction inlet.

My design includes a gate valve and strainer within the 10 pipe diameters.

Is the strainer allowable in this range?

I'm unable to find in NFPA 20 any input on this. Thanks in advance.

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I have question regarding fire pump capacity.

In my situation the water department is requiring a city tap size to be 2 pipe sizes larger than the fire protection backflow preventer.

In my project, I was using a 4" backflow and 400 gpm fire pump so my underground/city tap would be required to be at least 6 inches.

The AHJ is requiring me to increase the area size in one of my remote areas. So, my sprinkler demand now becomes 582 gpm. To avoid having to use a 500gpm fire pump (with a minimum suction size of 6-inch) and increase the underground to 8-inch, could I still use the 400 gpm fire pump to supply the 582 gpm demand?

This comes out to about 145% of the pumps rated capacity.

I have never come close to the 150% mark before and just want to see what others think. If the underground size wasn't required to be 2 inches larger I wouldn't even think about it and go with the 500 gpm pump.

Thanks in advance.

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NFPA 20 says that if the test header supply main is more than 15 feet from the fire pump, it must be increased one pipe size or hydraulically calculated based on 150 percent of the rated pump capacity.

What form does the hydraulic calculation take?

Are we trying to determine if the main can flow 150 percent of the pump rating without running out of pressure?

How low a pressure would be acceptable?

Is this a one time calculation to size the main or is this a calculation that must be performed during each annual fire pump test?

Thanks in advance.

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For a fire pump subject to NFPA 20, I know that the suction side requires an eccentric reducer, but “can” one be put on the discharge side?

I have a situation where we are removing and replacing existing pumps where both the suction and discharge are at the same elevation, but the new pumps have the discharge about 2.5” lower than the suction.

I am trying to find a solution to resolve this. Thanks in advance.

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Can the pipe from a remote FDC at the front of our building route under the building slab to connect to our fire pump room at the back of the building?

The Fire Pump Room is on the basement level.

This is for a six-story hotel with a partial basement along the back portion of the building that is open to a lower grade level in back. Here's a sketch below.

The fire marshal requires a remote FDC at the sidewalk in front of the building. Our fire pump room happens to be on the opposite side, in the back.

The most straightforward routing is below the building, but it is minimum 60' of run which certainly exceeds the 10' maximum distance allowed for the fire supply from NFPA 13.

Going above the first floor ceiling is challenging given all the interiors/ceilings, public spaces, and glass at the street front.

Given that the FDC pipe is normally-dry and not pressurized, do we have the same restrictions of 10' max below grade?

Even if not, can't say I'm thrilled about having that many joints below our building above. Thanks for your help/thoughts!

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For determining the capacity of a water storage tank, is the tank capacity calculated by the max flow extension of a pump curve or by 140% rated capacity? Or could it even be 120% of the pump rated capacity?

Looking for guidance on how the pump size and water storage tank size would be directly related.

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I was recently cited by a surveyor for not having supervised control valves (isolation gate valves) on the jockey pump.

All other control valves are supervised for the riser and fire pump. I view the jockey pump as not critical or a necessary part of the fire pump and would not have an adverse effect if the jockey pump were out of service for any reason.

Is there a NFPA code reference that requires supervision on jockey pump gate valves?

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I am trying to understand how low suctions control valves in a fire pump work.

At what point would you need to have one? Could anyone help me understand that?

Thanks in advance. 

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I'm looking at a few projects that have fire pumps and above-ground cylindrical storage tanks for fire protection.

Some projects I have seen have recirculation after the fire pump discharge underground and back into the storage tank. Frustrated I can't find much on this in NFPA 22 or elsewhere.

Is this part of a means for freeze-protection, or to keep the water from getting stagnant, or for pump testing (in which case I guess it would have to branch off from the flow meter)?

Or is it likely engineer preference? Is it a military requirement?

Thanks in advance.

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I am doing some work on a combined fire-fighting/domestic pump house for a small community.

A couple things look odd to me.

1. They have a 12-inch flanged basket strainer after the pump discharge just before the mains. I was under the impression that any devices or fittings between pump discharge and need to be listed for fire protection use.
   
2. Instead of a jockey pump, they have three potable water pumps which run all the time pushing potable water to the mains. The primary fire pump automatically operates when the pressure drops to 4.5 bar and the backup pump at 2.3 bar.
   

There seem to be two deviations from NFPA standards here:

First, the jockey pump should be small , so that in case of fire it is the fire pump taking the load, and second, the starting sequence requires the jockey pump to start above the fire pump churn, the first fire pump a little lower and so on.

Is there any exception for such combined domestic/fire protection systems in the NFPA line of standards?

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What is the best procedure to use when testing a 3,500 gallon diesel fire pump that is equipped with a throttling/pressure governor installed on it?

My graph was well below the rated curve at 50% and 100%, but the governor seemed to disengage at 150% flow and my numbers exceeded the rated curve when we pushed this much water.

I did not attempt to change the controller settings or unplug the device (if that's even possible) to disengage the forced idle at 50% or 100% but insurance isn't "buying" that the pump didn't fail. These pumps aren't more than 5 years old and are ran on a tight schedule once a week (by the way).

Maintenance thinks it'll lead to faster wear and tear on the motor and I agree. All I could really do was state the facts and hope I don't have to go back out there and do the test again.

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We have two fire pumps on a project which are to be connected to one emergency generator. One is a primary pump, the other is a backup.

Will these ever run simultaneously?

The Electrical Engineer on the project is concerned about running supply for both pumps simultaneously and overburdening the generator. 

Is there an NFPA limitation for this, or requirement either way?

Thanks in advance.

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Is there any NFPA provision for forbidding a fire pump to start in the event a water storage tank has a water level that is too low?

I'm wondering what might happen if the water storage gets down to ~25% of the design level, or lower, and the potential need to shutdown the pump before it runs dry. 

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I live in a province in Canada with its own building code version and recently had a project for a very small, single-story building - an industrial class with an incinerator.

We were originally told that the building needed to be sprinklered so we designed a system for it. Since the system will cost a lot of money, the owners have hired a code consultant that concluded that the building does not need to be sprinklered as there is no requirement to sprinkler a single-story very small industrial building by the building code.

They make the argument that standards like NFPA 82 & NFPA 20 (for fire pumps) pertain to the equipment but not the building as those aspects are covered by the building code. They also mention this usage has been called into question and accepted in other Canadian provinces with similar code structures.

Noting that this argument is not specific to the incinerator or NFPA 82 but any equipment or room covered by an NFPA standard, I'm wondering if anyone has heard a similar argument or has other experience in another jurisdiction.

Does the usage here drive a requirement for fire sprinkler protection?

Is this the correct approach here?

Thanks in advance.

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Are there any good practices or other viable options allowed by NFPA 20 (other than a Pressure Limiting Driver) to limit the fire pump discharge pressure to at churn to 175psi when there is a high static pressure on the water supply?

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We are bidding a job that may possibly need a 1,250 gpm rated fire pump due to not enough flow from the city. Our test was 43 psi static, 35 psi residual at 872 gpm. We will need to include a ground suction tank.

How do I correctly include or simulate a ground suction tank in my hydraulic calculations?

We use the Sigma Hydraulic Calculation program.

Thanks in advance.

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Is there a code or standard that specifies floor clearance in front of a fire pump controller cabinet?

I am installing a fire pump in an existing building which has a controller with a transfer switch. Of course the fire pump room size presents clearance issues.

I have clearances I need for sprinkler pipe, but I do not know the working clearances required in front of the cabinets. 

I do have door swing clearance, but was wondering about a working clearance. Thanks in advance.

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We have a two-zone fire sprinkler system, one is wet, the other is dry-pipe. There are no inside hose valves, just a small NFPA 13 building.

Does the fire pump size need to accommodate hose allowances?

The sprinkler calculations have no inside hose allowance. We would typically apply the hose allowance at the city tap, which would be upstream of the fire pump. 

Thanks in advance.

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Does a diesel-powered fire pump require a full flow relief valve to prevent over pressurization due to a RPM governor failure?

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Under NFPA 20, Section 4.20.7.1: 

The circulating relief valve shall actuate below the opening set point of the pressure relief valve to ensure cooling of the pump during churn operation.

NFPA 20 Handbook:
​
The pressure setting of the circulation relief valve should be well below the pressure relief valve setting but above the maximum suction pressure.

Based on this, how do I properly specify the circulation relief valve setting that is installed on the pressure relief valve discharge line if the pressure relief valve set point is 175 psi?

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When doing an annual test today for large fire pumps with a combined test header, I was told that most inspectors throttle and send water to the pitot gauges by using the butterfly valve inside the pump room and keeping the control valves wide open outside on the test header.

I disagreed with this approach, as my mentor in the industry taught me to first charge the test header and then get your pressures by opening each outside control valve individually to get your pressures. He said this is so that you don't burn up the rubber on the inside test header (normally-closed) butterfly valve. He said it happened to him in the past and then the building owner is left with a leaking test header control valve and the danger and costliness of a test header full of water.

Is there a correct way (by code) to get your pitot reading off the hose monsters outside (what I mainly using) or is charging water one way or the other simply a matter of preference?

I hope this makes sense.

I understand some test header control valves are OS&Y but most all the outside components I come across are the test hose connections that open and close via the gate valve.

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Is there a minimum distance requirement between a unit heater and a diesel fuel tank within a fire pump room?

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There's a project in our jurisdiction that is a warehouse with a detached fire pump building.

They are proposing to feed the controller for the diesel fire pump (in the detached fire pump building) from the service in the main warehouse building.

Are there any relevant fire codes or standards that require the controller to be fed from a separate service?

Or, at least fed from a service that is "dedicated" to the fire pump building?

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We have a newly-installed electric (duty) fire pump, and a back-up diesel fire pump. 

Each pump has a 100% required flow capacity for the system (750 gpm each) for the building.

Is it OK to run the two pumps simultaneously during testing - which would result in a 200% flow?

The diesel pump is only intended to be used during power interruption/worst-case, but not with normal power online.

During testing, we release water in the test line (flow meter) - the pressure went down and triggered the cut-in pressure of both the electric and diesel pump which makes it run simultaneously (electric first, then the diesel a few seconds later).

Does this not have a water hammer effect on the system?

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Working on a project with an underground water storage tank, where the water level is under the pump suction inlet. The pump type is a vertical turbine pump.

Is the a maximum vertical length of suction pipe for this type arrangement?

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