Wall Hydrants

[bmlxd40]

Does NFPA define hydraulic criteria for wall hydrants? I have looked, but if it's there, I missed it. There is a FPE involved in this project, so I have asked him to define the calculation criteria. I was just wondering if I overlooked it somewhere.

 

[cdafd]

What kind of business will these be at?

Where will they be located?

How many??

Who is requiring them???

 

[bmlxd40]

This is at a bus maintenance facility. There is one existing wall hydrant located on a remote corner of the building. It was presumably installed when the facility was built in about 1980. I am thinking that it was installed originally because there are no standard hydrants anywhere close or accessible to that end of the building. The scope of this project basically a complete fire protection upgrade.

The hydrant is connected to one of the existing sprinkler cross mains. I'm fairly certain that the current pipe sizing (mostly 4") wont support the wall hydrant alone, much less the wall hydrant and the sprinkler system.

 

[cdafd]

Wall hydrant or standpipe??

How many outlets??

And take it the entire building is sprinkled???

 

[bmlxd40]

Two outlet wall hydrant in a fully sprinkled building.

 

[cdafd]

I have only seen it once, and the person requireing it did not require any set flow or pressure.
ther was an fdc to pump through, but???


It was also tapped off the fire sprinkler system.

do not think you overlooked anything out of nfpa, guess someone needs to tell you how much water and pressure they want.

 

[TravisMack]

I have seen these a couple of times. I questioned the engineer involved. He wanted it to be like a standpipe and flow 500 gpm @ 65 psi (at the time that was all that was required under BOCA) and just be calculated to the FDC. My question was that if it was a standard hydrant on the site fire line, it would have been required to be 1500 gpm @ 20 psi, so why could he call it a "wall hydrant" and only have to make it 500 gpm? The answer I got was just to do it as specified and nothing more.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[MGXFP]

I've done these before, but added the hose stream at the wall hydrant instead of the fire hydrant off the water main for the calculations.

 

[bmlxd40]

TravisMack: I had the same thoughts. Especially since there are other outbuildings and buses in the rear parking lot with no available water supply other than the wall hydrant or whatever the pump truck has on board.

Cdafd: Thanks for your help. I'm going to get the FPE's input on this.

Newtonfp: I think that is the way to calculate it,I believe you hit the nail on the head.