FDC's for sprinkler systems

[npfd801]

All this talk of K factors, NFPA codes etc. is giving me flashbacks. I once designed fire sprinkler systems for a living and now I'm having cold sweats... Nothing more fun than hydraulic calculations for a sprinkler system.

I understand that there are some hard and fast rules we have to live by in the fire service, but like everything else - I think there needs to be an educated decision regarding what priority connecting to the FDC is in our order of initial ops at a suspected or actual structure fire.

Say perhaps in a residential occupancy with a high potential for many lives to be at risk unless a well involved compartment fire is knocked down quickly. If the building is sprinklered, and you see flames blowing out of a window, I would say something is going on with that system. Do you take your chances and boost the FDC or do you make an aggressive attack and go after it? I know what my answer would be.

By the same token at a business occupancy at 3 am with no cars in the lot, I might commit my crew to pumping that FDC before I send anyone in...

I'm tired, and it is late, but that's just my food for thought on this one.

[FFPotenziano]

If your pumping the FDC at 150psi for 5 minutes and you realize you need to increase the pressure, would that be an indicator that more heads have opened and fire is growing?

If you can't compress water, why not pump to the FDC? You'll make up the pressure loss and you'll have a gauge on the FDC (your pump).

[InsuranceLCRep]

[QUOTE=FFPotenziano;929090]If your pumping the FDC at 150psi for 5 minutes and you realize you need to increase the pressure, would that be an indicator that more heads have opened and fire is growing?QUOTE]

Yes, as more sprinklers open the pressure will drop, indicating the fire is getting larger. Depending on the occupancy and hazard u may see a big drop or a small drop. An office the design is about 10 gpm per head, so if 6 heads activate u will be flowing about 60 gpm. If this is a warehouse the flow maybe 60-100 gpm per sprinkler, same 6 heads, now u are flowing 350-600 gpm, u will see a drop in pressure with this flow.