Manual Standpipe in a High Rise building

[RBK]

Despite the requirements of NFPA and the building and fire codes, one of the jurisdictions I work in informed me that they want a manual standpipe system in a new high rise building. From the perspective of my company, this isn't such a bad thing. The system will certainly be less expensive; smaller fire pump and storage tank, fewer pressure reducing hose valves, less drain piping, etc.

Any thoughts/concerns about a manual standpipe in a high rise? Any liability issues to consider?

 

[Coug Dad]

I would supervise it with water pressure so you know if a 2.5 inch fire hose valve is tampered with and left open. This would make it a manual wet as opposed to a manual dry. I am all in favor for letting the Fire Department control the fire fighting water supply through thier trucks and the FDC. Much more reliable than a fire pump within the building.

 

[AegisFPE]

This may be a reasonable approach for "short" high-rise buildings, but should not be a blanket statement for all high-rise buildings. For "taller" high-rise buildings, there is a point where fire apparatus, even pumping in tandem, could not effectively provide the required flow to the roof.

 

[Dr. J]

Get their direction to stray from the adopted codes in writing of course. They should confirm (in writing) that the FD aparatus is capable of serving the standpipe water demand and pressure, this probably requires your input as to what is required at the FDC.

I am not so sure you will have fewer pressure reg. hose valves. The pressure required at the base should be no different whether it is a FD aparatus or a building fire pump providing the required pressure for the top of the riser. Wherever this exceeds 175 psi (typically any floor lower than about 10-12 stories from the top) a prv should be installed. I am not sure drainage is any less either.

CD's idea is good. You can probably use the manual wet standpipe riser as a combo sprinkler/standpipe and avoid a separate sprinkler riser. Thus the system would look pretty much like a fully auto wet standpipe, just with a smaller fire pump.

 

[AegisFPE]

I think the absence of PRV's would be based on the assumption that there would not be fire hoses flowed from the top and bottom of the standpipe simultaneously, and the FD apparatus would pump only the the pressure required on the floor(s) where hose lines were in use.

 

[RBK]

Thanks for the responses. The system will be manual-wet, and they actually require separate standpipe and sprinkler systems, with a "priming" line, to keep the standpipe wet and notify if a valve is open (without tampering every hose valve). I have the requirement in writing, though I am awaiting a confirmation of some of the specifics, such as that their apparatus is capable of the pressures needed for this building. It is a "short" high-rise, only 21 stories, so the 200-210 psi required at the FDC should be within their capability.

Bonus points to Aegis! That is exactly the argument I used when discussing the requirements with the FD. Fortunately, they agreed with me. That saves some pressure reg. hose valves.

Coug Dad, do you know of any jurisdictions that prefer manual standpipes for high-rise buidlings, or is that just a personal preference? I am of the same opinion, at least within the ability of the FD pumper apparatus. Fire pumps in the building, even with backup generators, dual water supplies, and even backup-pumps, will never be as reliable as the FD, in my opinion.

Any concerns about violations of the state building and fire codes, or the fact that this requirement is not included in their municipal code, but is only part of a fire department "handout"?

 

[Dr. J]

Interesting concept. From an engineering standpoint I like it. I can't comment on FD ops, but modulating the pumper outlet pressure to only what is needed seems like a good idea, rather than just brute forcing everything.

Tell me more about the priming line. Is this off a separate jockey pump to maintain the column of water all the way up? Off the sprinkler fire pump? Off a domestic water booster (guessing not this)?

Fire pumps for standpipes have always bothered me. Similar to hoses in cabinets, and Class II standpipe outlets, the only people who should use the fire valve outlets show up to the incident with well maintained hoses and the biggest pump in town (high-high rises are another thing). But like I say, I don't have the background to debate FD operations.

Will the demand calculated back to the hydrant need to include the sprinkler demand PLUS the standpipe demand? In a combo sprinkler/standpipe system the spinkler demand does not get added to the standpipe, and the standpipe demand is limited to 1000 gpm. Did the FD address this?

 

[RBK]

The priming line is a small line, typically 1", that connects the sprinkler system to the standpipe system. It has a shutoff valve, check valve, and flow switch, to detect if a hose valve is opened. The standpipe system is thereby pressurized to the same system pressure as the sprinklers, but as soon as a valve is opened, the flow through the 1" priming line can't possibly keep up. As far as the fire department is concerned, the pressure in the standpipe system is not important, it is just a matter of keeping the standpipe system full of water. For a system with a fire pump, the priming line would be supplied by the jockey and fire pumps, or by the city supply (via the bypass line) if the pumps were off-line for some reason.

Interesting point about the sprinkler and standpipe demands. For the building in question, there is no calc back to the hydrant because the water supply is via a break tank. But even for more typical buildings, you don't need to account for use of both sprinklers and standpipes at the same time. The water supply needs to be adequate for the larger of the two (sprinklers plus hose allowance, or standpipe), but it's not expected that the systems meet their respective demands simultaneously. Once the FD is connected to the standpipe system, the sprinklers are no longer responsible for controlling the fire. If the combined demand of the sprinklers, standpipes, and any attack lines the FD is using from outside the building, is in danger of overwhelming the city's supply, they have a big problem.

 

[Insurance Engineer]

Despite the requirements of NFPA and the building and fire codes, one of the jurisdictions I work in informed me that they want a manual standpipe system in a new high rise building. From the perspective of my company, this isn't such a bad thing. The system will certainly be less expensive; smaller fire pump and storage tank, fewer pressure reducing hose valves, less drain piping, etc. Any thoughts/concerns about a manual standpipe in a high rise? Any liability issues to consider?

You may want to consider if the fire proteciton system does not meet NFPA or any codes, most insurance companies will either NOT write the insurance for the building OR charge a LOT more for the coverage. That can be a lot $$$ over the life of the building.