Flow Switch on Discharge Side of Fire Pump?

12/9/2024

Is a flow switch required on the discharge side of the fire pump on the pipe before it exits the pump room?

We have an approved job that does not have a flow switch, and the fire marshal is requiring one.

Thanks in advance.

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20 Comments

Pete H

12/9/2024 06:42:00 am

My immediate questions:

1) Is this pump fed from a tank?
2) Is this a displacement pump?
3) Are there separate isolated alarm/control valve system risers in the pump room downstream of the fire pump?

If a yes to the first two, it might need to be a full flow meter as opposed to just a flow detector.

If yes to the third.... yes, put a flow switch on each riser.

I can be wrong.

Glenn Berger

12/9/2024 08:09:39 am

My questions will be:

How far is the fire pump from the suppression system distribution?

Are you feeding standpipes and sprinklers?

Is there a flow switch present downstream?

Casey Milhorn

12/9/2024 09:08:04 am

I believe NFPA 14 now requires this if you have standpipes/hose valves. From a practical perspective, 100% of the time provide a flow switch. I've heard too many stories about hose valves being opened up and/or leaks occurring and flooding stairwells, basements, and/or adjacent properties. If you are a contractor, I would go through the RFI process though if it isn't contractually required by the standard or design intent drawings/specs.
Also, you should be able to program the panel to report a "feed main" or "hose valve" signal when only that flow switch is triggered, if this switch AND a sprinkler zone flow switch is signaled, just report the zone that is flowing. Not an alarm guy, but I'm fairly confident we have made this happen before.

Franck

12/9/2024 09:08:35 am

The technical answer is no.
When the pump starts (and deliver flow), you already have an alarm. Why asking for a second one ?
But you need flow switches for the different systems downstream (hoses, sprinkler risers) to know where you are delivering the water.

Anthony

12/9/2024 09:13:31 am

From a practical sense if the fire marshal is requiring it just install it that's not a fight worth fighting.

Code wise NFPA 20 doesn't seem to require it. how ever NFAP 14 specifically the diagrams on A71.(a), (b) and (c) do show a flow switch a pressure gauge after the pump assembly. So depending on the application that may be where the requirement is coming from?

Dan Wilder

12/9/2024 09:58:10 am

I will disagree with this method of thinking all day. Is it a hill I'm dying on, maybe-maybe not but it will always be under protest with the GC & owner involved so I have a means to recoup costs.

The purview of any given AHJ is based in either legislated & adopted building codes (IBC/IFC/NFPA) and referenced standards or published risk mitigation (FM Global, UFC). There is little allowance for a code official to require something without one of those two items above to reference back to as justification.

In simply complying with what an official feels or thinks opens up a checkbook that no contractor wants to fund. "Just adding the flow switch" would require a system shutdown (fire watch), materials and labor for the install, Fire Alarm wiring/programming/testing, and now an additional ITM aspect for the owner.

Jesse

12/9/2024 11:42:02 am

I agree with Dan here. I'm never afraid to question the fire marshal and stand up for my position. I was one for a long time so I kind of have an inside track.

I have never, ever lost a fire code appeal. But that that is because I pick my battles very carefully.

Dewayne Martinez

12/11/2024 07:57:22 am

I agree with Dan also. We have quite a few AHJ's that request some "wild things" during inspections. We politefully ask that they send us their requests in writing with the specific code reference so that we can send it along to the GC/Owner. Most of the times the issue just dies there.

Anthony

12/12/2024 03:40:24 pm

Dan, you're right, I'm wrong or at least I'm narrow in my view. I'm looking at this question as a design reviewer/engineer not as contractor or GC. I 100% agree if this is a post instillation comment then I'd fight it too.

Ray J link

12/9/2024 09:41:11 am

It's easier and less expensive to just state your case to the AHJ, (Authority Having Jurisdiction), and then do whatever they wish. You have to have the knowledge and street smarts to know when to go with the flow and when to fight, so to speak.

Jack G

12/9/2024 09:52:43 am

I agree with Anthony on this one.
Also its not a fight worth fighting.
There is a pump run in the panel so im curious why anyone wants a flow switch.
But its a combined system and as the individual zones and risers have alarms why shouldnt the combined system have a flow switch alarm like the sketch in nfpa.

Jose R Figueroa

12/9/2024 10:31:22 am

Assuming the Fire Pump system is installed in accordance with FM DS3-7 or NFPA 20 (supporting standpipes, hydrants, fire hose stations, and sprinkler systems), the response to the query is NO.

The pressure switches for both the jockey pump and the fire pump are typically located in the <FM> or UL Fire Pump Controller.

I appreciate the guidance from the Fire Marshall, and I would like to understand the reasoning behind the request for a water flow switch on either the suction or discharge sides of the pump. It seems that installing a flow switch at the Base of Riser (BoR) of a sprinkler system would detect flow and send an alarm more quickly than a switch installed downstream.

Could you please clarify the reasoning for this request? Thank you!

Jack G

12/9/2024 10:39:32 am

I think the intent…..is to install an alarm “ on the system”. The system being “ the combined standpipe/ sprinkler system”.
I m not sure that’s what he was going for, but shouldn’t be a big deal.
If you decide to do it be careful. Install it “after the junction of the bypass and pump discharge “ so that any flow from the bypass would be detected too.

Jose R Figueroa

12/9/2024 11:03:52 am

The alarm may not be needed in this situation and could lead to confusion. The fire pump controller is designed to automatically activate an alarm when the motor or diesel engine starts running, ensuring that any necessary action is taken promptly. Please refer to FM DS 3-7 or NFPA 20 for further guidance.

Additionally, I have observed similar issues in other countries due to misinterpretations of the referenced standards.

Jack G

12/9/2024 11:13:00 am

The text clearly shows a flow switch on the combined system. So argue the controller will signal this alarm. If the AHJ does not agree then bite the bullet and provide. The AHJ has the last word. If not shown on the contract documents ( which usually includes the clauses provide — per NFPA and AHJ ) you may be able to wiggle a change order. My opinion…..not.

Ronnie Morales

12/9/2024 11:14:22 am

Why not ask the AHJ to show you where the requirement is coming from? Then you can have a discussion if it's required or not.

Patrick Drumm

12/10/2024 07:33:46 am

I agree with Ronnie. It is always best to understand what code/section the AHJ is referencing.

One of two things will happen. You can find out that indeed, you didn't see something in the code and will gladly fix it on the current project and future projects, or the AHJ may be mistaken and you have a discussion so this does not continually come up (especially if you're in a jurisdiction you do a lot of work in).

Ronnie Morales

12/9/2024 11:35:35 am

Here is a requirement.

Stationary Fire Pumps and Standpipe Systems Handbook 2019

4.20.5.4 If a closed-type cone is used, it shall be provided with means for detecting motion of water through the cone.

Relief valve discharge is permitted to be piped back to the suction side of a fire pump (closed loop). Where this piping arrangement is used, a method to detect flow must be provided, such as a flow switch connected to a local bell, or a closed waste cone with a sight glass. This arrangement also necessitates the installation of a circulation relief valve for cooling purposes (see 4.20.7.1 for additional details). This
arrangement is shown in Exhibit I.4.28. Relief valve discharge is also permitted to be piped back to the water supply source, such as an aboveground water storage tank, as shown in Exhibit I.4.29(a). A method to detect flow is also required in this case since flow will not be readily visible, unlike cases where the relief valve discharge is piped to an open drain, as shown in Exhibit I.4.29(b).

Jose R Figueroa

12/9/2024 12:40:43 pm

This response may not align with the Fire Marshal's requirements. In confined spaces where the visibility of water flow through relief valve piping is limited, a closed-type cone or V-Cone® differential pressure (DP) meter could be more appropriate. So, this is an entirely different issue.

PS to the engineer who posed the question: please provide the specific Fire Marshal requirements. Thank you!

J.H.

12/9/2024 12:12:51 pm

What is the exact wording of the write-up from the fire marshal?

Ask the fire marshal to please provide the Code section supporting the requirement. One or both of you will learn something new.
After that, please post the outcome in this thread.

Flow Switch on Discharge Side of Fire Pump?

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