Fire Pump selection for a fire hydrant 2

[madvb]

Hi,
I'm trying to select a packaged diesel fire pump to provide flow to a hydrant on a site. The facility is connected to the city's fire water line, but does not have enough pressure. If a fire hydrant is required to have 1500 gpm at 20 psig, does one select a pump for 1000 gpm or 1500 gpm?

I think NFPA 20 mentions something about the fire pump being able to handle 150% of its rated capacity. Can I say that my pump "rated capacity" is 1000 gpm, and therefore, 150% of my rated capacity is 1500 gpm, and would meet the fire hydrant flow requirement? Or do I select a pump for 1500 gpm + 50% = 2250 gpm?

If the facility has a fire hydrant (1500 gpm) and 2 buildings (bldg A: 225 gpm and bldg B: 300 gpm) that require fire sprinkler system. Does one size the fire pump for a fire hydrant + bldg B = 1800 gpm, or just the worst case (1500 gpm)?

Thanks.

 

[madvb]

"Heat tape works for very small runs line passing through an unheated space but not intended to heat entire system."

Really? Going through Tyco (Raychem), it seems that it would be ok as long as your circuit breaker and transformer is sized for it.

How do you guys deal with piping (domestic water and fire sprinkler) installed in the attic where insulation is at the ceiling and your design temperature is in the 20's F ... or even in the 30's? Dry-pipe or glycol system?

 

[pipesnpumps]

madvb,
I've been reviewing other people's submitted plans for about 1 year, and have yet to see a glycol system. The typical method is a dry riser off the lead-in, or could even be off a wet feed or cross main, even a branch, as allowed by code, but this would put the compressor somewhere else in the building..

I believe I read somewhere that with the cost of dry pipe systems now they are the preferred method, but I don't know much about the cost side of things yet, only engineering/code side.

That is a good question though, I hope you get some good answers.. I'd like to know too.

 

[TravisMack]

It depends on the project. I have seen some rather large anti-freeze systems. You now have to use the DW method for calcs. I have found that it can make quite a large swing in demands and therefore pipe sizing when you factor in solution density and viscosity. AF is typically chosen when doing residential projects and we can use tyco attic heads and keep everything as CPVC. If we are using steel, then typically just do a dry system.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[spkreng]

Just an off topic notice: NFPA 13R AND 13D are going to disallow anti-freeze systems "new TIA approved"

spkreng, CET

 

[SprinklerDesigner2]

spkreng,

Thanks, I didn't know that until now.

 

[Arsnman4]

Just an off topic follow up question regarding 13R and 13D anit-freeze......isn't it just Glycerin or Glychol (can't remember which one exactly.... being late Saturday night and all) since Blazemaster/ Lubrizol has a listed application for use?

"Fire suppression is a failure in prevention"

 

[Arsnman4]

To follow up on the "off topic" 13R and 13D information on the "Proposed TIA # 998 with comment closing date of 7-23-10"

The proposal is to not permit solutions in excess of 50% [7.6.1] and that factory pre-mix solutions will be permitted [7.6.1.1] based on UL document and FPRF report.

"Fire suppression is a failure in prevention"

 

[spkreng]

Your right, I had opened a diff comment, apologize for any confusion or heart attacks.....

spkreng, CET