Re: fire fighting pumps

Years ago, I used to work on fire department apparatus including pumps used on fire trucks. The pumps were basic centrifugal pumps with cast iron housings and bronze impellers. They could be either single stage or two stage. Two stage pumps could be used with both impellers in parallel to maximize flow for a given rpm or in series to maximize pressure for a given rpm. The pumps were optimized for maximum pressures of 300psi or less.

I suspect your "fire rated" refers to certification by nfpa. The nfpa certifies all matter of devices connected with fire protection similar to UL certification of electrical apparatus. There are two "nfpa" certifing organizations. National Fire Protection Association (nfpa.org) and National Fluid Power Association (nfpa.com). The second is more familiar to users of this newsgroup. They are not connected.

Fire pumps are not self priming per se. On all the apparatus I worked on, the pumps were located below the on board tank so they had flooded suction. Alternatively, the pumps could be supplied by a pressurized source such as another fire truck or a hydrant. When pumping from a static source below the pump inlet such as a lake or river a separate pump is provided that pulls water into the fire pump inlet through a orifice in the pump inlet. The priming pump is typically a vane pump but older apparatus sometimes used gear pumps. On some apparatus, priming is accomplished by using a device that routes engine exhaust through a venturi. My experience is that this type of priming device is limited to small portable pumps used primarily for wild land fire applications.

Once primed, the centrifugal fire pump can lift water a maximum of 30 feet but in reality, total head should be kept much less than that. As head increases, the volume that the pump can deliver drops off.

"John Manders" wrote in news:bd6r0e$ snipped-for-privacy@newton.cc.rl.ac.uk:

>> hello all, >> >> does anyone know if a fire fighting pump is different from an >> ordinary domestic/industrial pump?i'm asking this as there's no >> mention about differences in catalogues, they say that X pump can be >> used for industrial/domestic/fire-fighting applications. >> >> but i heard from someone that firefighting pumps are made from a >> different alloy and are more robust pumps. they also have a 'fire >> rating' >> >> can anyone enlighten me?? thx >> >> > The pumps used on fire tenders are different as they have to self > prime when drawing from rivers etc. As far as I know, fixed pumps are > normal industrial types. > > John > >
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Jon Juhlin
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