fire flow requirements

[colum]

I am working on a Preliminary Report for a water supply scheme, mainly rural in nature but with some villages. I am trying to find some definitive guidelines in relation to fire flows, i.e. what fire flows to provide in villages and rural areas, how long the fire flow should be available, at what pressure, and is it usually modelled with peak demand or average demands??

 

[quark]

Depends upon your local statutory requirement. For example, here in India, we have to provide 700lpm from one hydrant and the pump discharge pressure is about 7kg/sq.cm. Each hydrant should conver a radius of 45 meters of periphery. This decides your no. of hydrants. The pump capacity should be based upon 1/10th of hydrants running at a time and the reservoir capacity should be sufficient to take care of 2hrs of pump operation.

NFPA guide is a good reference.

 

[eddieng27]

colum,
If there is a fire department around, talk to them. If there is no fire protection now, the fire department will likely be thrilled to get almost anything. 1,000 gpm to 1,500 gpm is really considered the minimum now days. 2-hour durations are in order for these flows; if higher flows, you'll want to provide storage/ pumping for a longer period of time. Take into consideration water quality degradation issues though if the system is so small that water age creeps up there with a large tank. Is your fire system also a potable distribution system? If so, you'll need to consider system pressures under fire flow conditions. Typically you'll want to provide fire flows such that the minimum pressure in the potable system remains above about 20 psi. You could also consider providing water cisterns for the fire department to draft from. Maybe you can consider lakes/ ponds sources if you have them in close proximity to the various villages.

 

[AegisFPE]

If you are unable to provide the FD's minimum flow, the development may need to plan to install fire sprinkler systems in the houses (NFPA 13D). This should be discussed with the jurisdiction in advance, but will need to be anticipated in the size of the laterals leading to the home sites.