Fire Sprinkler System Test/Drain to a Mop Sink?

4/3/2019

Does anyone have successful experience with routing a fire sprinkler drain and/or inspector's test to a mop sink?

I have a client that has a 12" deep mop sink in a janitor's closet which the contractor is asking to as the discharge for an inspector's test. I suspect that with the pressures on the system (~120 psi) and a typical 1/2" orifice, that the flow will be roughly 60 gpm (=5.6 x sqrt (120)). We are recommending a 4" plumbing standpipe to accept the inspector's test if a drain riser can't be routed to the exterior separately. What are your thoughts?

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8 Comments

Raul Vasquez

4/3/2019 10:10:33 am

Nope. Water everywhere.

Rusty Scott

4/3/2019 10:22:09 am

When I was a sprinkler contractor we took auxiliary drains to the janitors sink just to help drain the system faster for maintenance. But never a test and drain for testing.

Vince

4/3/2019 10:30:23 am

Depending what state your located in here, in Nevada we are not allowed to dump into a drain at all. The AHJ's and Water District does not allow this for the chemicals that are used.

PETE

4/3/2019 10:32:07 am

That's only allowed in Mississippi.
... just kidding.

Like others have said, that's too high of a flow rate. I will add that whenever an inspector's test or drain has been required to be run outside, we have been responsible for running it. I don't know if you're on the 30th floor of a high rise or in a basement.

You can get a test an drain with a sight glass for FDT for dry systems, and run a hose outside the building. They make them with a 3/4 hose connection. Also, there is a provision in NFPA 13 to use listed FDT software for dry system time delivery. In combination with flowing the system through a hose for valve trip and alarm annunciation, this is another option.

Kendall Nightlinger link

4/3/2019 12:03:31 pm

As the previous comments are stating, this is not a good idea unless you want black mud all over the walls adjacent to the mop sink.

Mike

4/3/2019 01:36:56 pm

There are tables in the plumbing manuals indicating capacities of drain pipes under various conditions. I'd simply give them the flow and have the mechanical engineer design it to release liability from you.

Doug Funk

4/3/2019 08:09:29 pm

As an inspector, I would not recommend an inspectors test into a mop sink. It rarely turns out well.
Running a drain/IT into a 4" vent crosses into cross connection issues. Water purveyors really frown on it.They only possible way is if the sprinkler system has an RPBA but check with your water purveyor.
Your best option is deffinately to run it outside.

Jesse link

4/4/2019 10:11:13 am

Agree with all - this would be a disaster. The mop sink won't be able to keep up with the volume, and we all know how pretty and clean AS water is.

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