Booster pump for fire protection system

Your sprinkler system designer and your property insurance carrier must be tasked with this burden. Past the design and layout of the sprinkler system and the fire load of the building, other factors will be the amount of water available from a municipal supply, plus whether a lagoon or suction tank is required due to insufficient municipal water supply.

Just my experience suggests that the horsepower of the fire pump will be approximately 120% of the building's square feet measured in thousands, i.e., an 80,000 ft.sq. single floor facility with a cement floor, concrete walls, a twenty-four (24) foot ceiling height will require at minimum a 100 horsepower pump. But this is just a reference as there are many other factors that can make a serious difference.

Ing. Robert Forbus

The first thing i thank for your comments.

But that is not matter which i mentioned. I already had the HP of fire pump, but i want to use a booster pump in order to maintain pressure in this fire sprinkler system due to some leakage occur in the mean time.

Any good experience give to me

Thanks and regards,

Phuoc

First check what is the required suction pressure of your firewater pump. The booster pump should be firewater pump suction pressure plus 20% of this pressure.

Eng. Khushdil Mahmood

Select a Pressure Maintainance pump with a shut off pressure of 5-7 psi higher than the required system pressure of the sprinkler system. Do not forget to take into account the pressure losses of any PRV, check valve, or piping due to the location of the PM pump (ideally right next to the main pump). 1 to 5 US GPM is usually sufficiant for leak loads. Remember that the PM pump is NOT the fire pump so keep it's flow low.

First of all, you have to figure out the demand on your fire protection system (i.e., flow and residual pressure vis a vis type of construction/risk). Fire hydrants, for instance, put a high demand on the public supply (e.g. 1,000 GPM at 20 PSI residual) This, however, could be reduced if the buildings were to be equipped with fire suppression systems (e.g. sprinklers).

A booster pump arrangement can be made of one or two centrifugal, multi-stage pumps (the latter arrangement is best for redundancy), connected in parallel, so that one pump can supply the demand, while the other provides redundancy. A professional engineer, with experience in the field of pumping systems design should be in charge of putting the design details together.

Are u actually asking for a jockey pump?

That's my understanding from your question. If it is so, it should be an online pump which shall mantain the pressure within a pre-determined pressure range. Once the pressure drops beyond this range, the main fire pump should kick in. Therefore to select this jockey pump, your pressure requirement and pipe size requirement should be known. Hope this was help-full...

I am glad that you brought up the jockey pump. In the States we tend to call the fire pump a booster pump, because most of the time its function is to boost the pressure and flow available from the municipal water supply.

The jockey pump does not have to be very large, and typically operates but a few seconds per hour with a new system that is free from leaks or backflow. What I typically see is a pump with two (2) or three (3) horsepower for a large system.

Ing. Robert Forbus

Jockey or PM (Pressure Maintainance) are really interchangable names for the same function of this pump, which is to keep the main fire pump from starting due to leak loads. In most parts (if not all) of the U.S., a main fire pump is not permited to shut off automaticlly. Once it starts, it runs until it gets shut down manually or blows up ... no low suction shut off ... no low/system pressure or high pressure shut offs permitted. You can easily see the importance of the PM pump. The PM pump should be sized so that at the flow of one (1) sprinkler head the PM pump pressure is not greater than designed system pressure of the sprinkler system (flow of one head + leak load and the main pump will start). Horsepower will be determined by flow and pressure (5-7 psi above system) needed to be supplied by the PM pump proper. With the controls for the main pump set at 2 psi below system (if your controls are accurate enough) and PM controls set at system psi for start and system +5 for shut off you shouldn't have a problem. Grunfoss makes some nice (electrical) stack pumps for this application.

is this a "wet" or "dry" system?

there is a device for maintaining air pressure in dry systems.

It's called an air maintenance device or furnas switch and a compressor.

Some people get paid to solve this problem, like me. Where are you located?

I don't know what jurisdiction you are in that has fire pumps that "blow up". Generally most fire pumps built after 1968 have a mercoid pressure switch that will shut them down once they reach the desired pressure. The mercoid switch is also standard in most jockey pump controllers.

What you should have said is in a fire after the pressure loss is too much for the jockey pump too handle the fire pump will kick on and not shut off until it is shut off or it seizes.

I don't really know too many people in the industry besides salesmen that call em PM(pressure maintenance pumps) either. Jockey pump is widely known in the States anyway, as the standard.

Thanks,

Mat

Go into Spirax Hookup - the chapter on selecting & sizing centrifual pumps or any pump manufacturer's selection catalogs, work out all the total heads ( all pipes, valves, fittings, vertical lifts, running length) mark it up as per manufacturer's recommendations to arrive at grand total head. Go to sizing chart read Head Vs Flow Gpm & select the size of the pump. Contact the Manufacturer with the selection and he will gladly help you out with the right pump.

well according to me, as the name suggests booster pump (which is to be installed on the terrace level/top floor area) is only to boost the water. To pressurize the system you can install pressure switches and you can maintain pressure always, but according to my knowledge it would be useless if you do so.. i insist of installing a booster pump on a manual mode where you can go and start the pump when needed. Booster pump does not need any calculation for load capacity etc. as it runs itself on gravity. So a booster pump of 7.5 h.p. @ 32 mtr head (i.e. water column) is sufficient.

Regards,

Vishal Shah