sprinkler booster pump for a part of the system?

[ForeverStudent]

I have a project for 7 story building with cellar (parking garage in the cellar, two stories medical offices and others are residential). My understanding - for parking garage I have ordinary hazard 1, in other places it is light hazard. My hydraulic calculations show that there is enough pressure/flow for cellar-third floors. Is it acceptable to install sprinkler booster pump just for a part of the system?

Thank you very much for the help.

 

[stookeyfpe]

Can you meet the standpipe flow and pressure demand without a fire pump?

 

[ForeverStudent]

Hi stookeyfpe, thank you for the response. I do not have a standpipe, just sprinklers. For cellar I do not need the pump, only for upper floors because of the elevation the pressure of city main is too low.

 

[stookeyfpe]

If this building is in the US, a standpipe is required, retroactively by the International Fire Code.

It would be allowable to only provide a fire pump for part of an automatic sprinkler system. However, that introduces a host of other problems. I would not present such a design to a code official.

 

[skdesigner]

Seems like if you're paying for the pump, you should make use of it. Decrease pipe sizes, use extended coverage heads, long flex drops to hit center of tile quick etc. Go to town.

If you've got systems before the pump, you'll need two separate fire dept. connections. Also, good idea to add check valves to the risers before the pump. Nothing like having the pump suck them dry during a flow test and then having every flow switch trip when they refill.

 

[ForeverStudent]

Thank you for the valuable comments.
Skdesigner, excellent catch. Stookeyfpe, I am in New York City, surprisingly standpipe is not required here if you are below 75' and do not have occupancy more than 30 people above 55' (subject to area limitations though). Could you please mention potential problems (aggravations) with this design?

 

[stookeyfpe]

You would be prudent to again review the NYC Building Code standpipe provisions. I read Section 905.3.1 and your only citing one requirements for standpipes. NYC has many others.

http://www2.iccsafe.org/states/newyorkcity/Building/Building-Frameset.html

 

[ForeverStudent]

Stookeyfpe, you sited correct section. However I have 4,300 SF on greatest floor, residential floors only 2,600 SF each. I believe that the standpipe is not required in this case. Am I missing something?

 

[stookeyfpe]

Looks like you don't need a standpipe. I checked the NYC FC and it has no retroactive standpipe installation requirements.

 

[TravisMack]

SKDesigner made some very valid points.

Since the project is going to have a pump regardless, why not take advantage of the pump on all floors to reduce installation costs.

With the setup you described, you should be able to pull all of that off with a 200-300 gpm pump at most. You may as well use the pressure for all systems to get the most bang for your buck from the pump.

I have done buildings where I had taken an in-rack sprinkler system off prior to the pump. This was a retrofit with an existing pump. When the occupancy changed, the new storage requirements (rack + overhead) were going to be too much for the pump. However, I was able to make it work by taking the in-rack off prior to the pump and just using city pressure for that. It all balanced and was good to go.

However, in your situation, I would not recommend splitting the systems as described. If you want to size the lower floors based on city water, you could still do that, but keep them on the pump. If the pump failed for some reason, you know that the lower floors would still be fine with the city pressure via the pump bypass line.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com