Is Sprinkler Waterflow Alarm Silenceable?

11/13/2020

We have a project where the AHJ is telling us they want the waterflow alarm to be silenceable. Our understanding under NFPA 13-2019 7.7 and 28.2.3.1 is that there must be an audible alarm within 90 seconds (per NFPA 72) and must continue until the flow stops, not when the fire alarm system silences the flow.

Are we correct in that waterflow is a non-silenceable event, by code?

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4 Comments

Jonathan Griffin link

11/13/2020 10:15:01 am

Remember to look at the opening pages of every NFPA standard: The AHJ may make interpretations as they see fit, and may also direct the Building Owners (and their contractors) to follow rules, procedures and orders that may alter what the relevant NFPA standard has published.
So long as Life Safety & Property Protection are supported & provided, the AHJ has the final say, not the standard.

Jake

11/13/2020 10:15:12 am

As an AHJ, we require an exterior horn/strobe above the FDC. This H/S is to be programmed to activate upon waterflow and not able to be silenced until waterflow stops. This exterior H/S fulfills the requirements of 7.7 and 28.2.3.1.

The interior notification appliances can all be silenced per NFPA 72.

Franck

11/13/2020 12:03:48 pm

7.7 indicates that an audible alarm should be available on the premises within 5 min after the flow begins and until such flow stops.

But if you you go to 16.11, you will see a different possible interpretation.

So as usual, the answer to your question is : that depends.

The waterflow alarm through the water motor and gong assembly is normally installed to inform people outside the building that there is a fire inside, so that they can alert the fire department.
This is particularly important for buildings not constantly attended (at night and/or during the week end) where you can count on witnesses in the street to alarm firefighters.

But it is not fully reliable as if this is the only fire alarm, there might be a long delay during week ends and nights.

In addition, this sole audible sound is very lound on the outside of the building, close to the gong, but light not be audible inside the facility (when process is operating and noisy) especially when multiple separation walls are provided within the premises.

But if you are in a constantly attended location and the sprinkler alarms for each system are reported to this location, it might be acceptable per the AHJ not to have the local water motor and gong assembly in addition.
Alarm will sound on the alarm panel and inform the right person to make the right decision.
And he can (of course) decide to sound the alarm off once he has been advised (otherwise he might get crazy listening to the alarm and might be difficult to call outside fire fighters).

To fully answer your question, it depends on factors that are not indicated:
are you speaking of the water motor and gong assembly alarm from the riser ?
is the location constantly attended and alarms reported to a central station constantly attended ?

In the second case, the guards may decide to sound an evacuation / fire alarm and at the same time inform the fire department or on-site fire brigade.

Jason Lupa, PE

8/19/2021 08:51:47 am

A fire department connection (FDC) is required for most automatic sprinkler and standpipe systems. Fire apparatus can connect supply hoses to the FDC to pump additional water/ pressure into the suppression system.

The IBC and NFPA 13 both require an audible appliance by the FDC, but it is NFPA 13 (3-10.1) that tells how to arrange the equipment to provide this outdoor audible signal. NFPA 13 also describes how the audible signal must operate: continuously (non-non-silenceable) as long as water is flowing. Sometimes jurisdictions adopt a local ordinance to add a visual signal and may even require a unique color. NFPA 72 has no requirements for outdoor notification by FDC’s.

NFPA 13 has two methods of providing the outdoor audible signal. A water motor gong is a mechanical device that is pipped into the water main and operates with water movement to sound a bell. As long as the sprinkler system flows water, the water motor gong will operate. NFPA 13 also allows the audible notification to be provided by an electrical sounder such as a bell or horn. These 120vac appliances are wired to the normally open contacts of a water flow switch (usually switches have two contacts; DPST) and will operate until the water stops. There is no requirement for battery backup or supervision. NFPA 13 only states that this electric sounder is to be wired in accordance with the NEC. Either method is usually supplied by the sprinkler contractor; the electric option is the most common for new construction.

Some engineers specify a dedicated non-silencable circuit from the fire control panel to supervise and control an weatherproof 24VDC bell. The bell would be programmed to sound continuously only for sprinkler waterflow conditions.

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Is Sprinkler Waterflow Alarm Silenceable?

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