First, for those of you who are not fire service types...you really need to get up to speed on the fundamentals and the tactics if you are designing what are manual firefighting components. Talk to your local FD's. They would be more than happy to give everyone a couple of hour "seminar" on the basic tactics and operations. After all, you are building stuff for them to use and they REALLY want/need it to work.
Fire apparatus pumps are variable pumps with the discharge volume and pressure output being determined by the incident and the actions of the firefighters/pump operator. You can flow 100 gpm at 50 psi and then jump to 1200 gpm @ 175 psi if you want by opening valves and adjusting engine speed. You can even get the pressure in the hose line to be lower than the city pressure if you throttle your valves. The point being that you cannot and should not treat apparatus pumps like a normal fire pump. There is a human in the way and you have to account for him/her in your calcs....hence my very first comment above. That said, as someone else stated earlier, it is fairly common for fire departments to tie-in to a sprinkler and/or standpipe riser and pump at 150 psi and adjusting engine speed to maintain this until notified to do something else. This is used for two reasons. First, 150 psi is some pretty good water pressure and works very well for the majority of sprinkler systems. Second, from a standpipe point of view, 150 psi is more often than not sufficient pressure to overcome elevation and friction losses to the firefighters on the tip (nozzle). They can call for adjustment at needed...and often do. Fight the fire in the basement and provide nothing less than 150 psi, when me and my crew get done taking a beating from our own hoseline, I will come outside and use whatever energy I have left to beat the pump operator into a bloody pulp. Conversely, if you are up to many floors firefighters can take a beating from insufficient pressure too...hence the code requirements. This is the reason you do the calculations...it prove whether your design is capable of providing adequate pressure and volume with the human factor in the system. We (my engineering firm) always assume that the water supply curve for a manual standpipe is 150 psi static, 150 residual, flowing the pumps rated capacity. For most designs this is ample...but you have to know what the pump capacity is (most today are at least 1000 gpm...but not all). If your demand is more than 1000 gpm, you need to get the info from the fire department directly...do not assume! If it turns out that to provide adequate volume and pressure at the top of the riser requires a tie-in pressure greater than 150 psi, make the FD aware (in writing) and mark it on the standpipe connection so that any responding pumper can read and knows what is needed. You can not assume that the first responding fire truck will the one closest or even from the same town. As for total water volume you have to meet the code requirements. No truck caries enough water. You have to have adequate city water, a tank, a pond, a river or a tanker (a "tender" to you west coasties) shuttle or a combination of them to meet the volume demand. I hope that helps. Paul Sincaglia, P.E. President, Firesafety Solutions, Inc. And Lt. Chagrin Falls Fire Department. _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
