Strainer for fire pumps
Strainer for fire pumps
(OP)
Hope someone could recommend me a appropriate mesh size for suction strainer of fire water pumps.
We have installed fire water pumps recently as bellows.
1) Main pump #1: 3,000 GPM (Driven by electric motor)
2) Main pump #2: 3,000 GPM (Driven by diesel engine)
3) Jockey pump : 300 GPM (Driven by electric motor)
*. Discharge pressure: 10Bar
*. Water tank capa': 5,000 M3 ( H: 20 METER, D: 18 METER)
The problem is the suction strainers on the pumps.
It's 40mesh strainer. During the 3 hours test run, the strainer clogged. We consider that the mesh size is not chosen properly.
I contacted the manufacture of the pumps and received the data as follows.
*Maximum passing sphere size through impeller, single stage:
Maker: Peerless , fire pump. cetrifugal
Motor pump: 0.95 inch (Pump model 10AEF20)
Engine pump: 1.38 inch (Pump model 8AEF15A)
With above data, it's very difficult for us to decide the appropriate mesh size for the pump.
Someone told me that NFPA does not allow suction strainer for the fire water pumps. Is that correct?
Regarding the water quality, it's relativeley clean.
The water is supplied from the make-up water for cooling water.
Many thanks in advance.
We have installed fire water pumps recently as bellows.
1) Main pump #1: 3,000 GPM (Driven by electric motor)
2) Main pump #2: 3,000 GPM (Driven by diesel engine)
3) Jockey pump : 300 GPM (Driven by electric motor)
*. Discharge pressure: 10Bar
*. Water tank capa': 5,000 M3 ( H: 20 METER, D: 18 METER)
The problem is the suction strainers on the pumps.
It's 40mesh strainer. During the 3 hours test run, the strainer clogged. We consider that the mesh size is not chosen properly.
I contacted the manufacture of the pumps and received the data as follows.
*Maximum passing sphere size through impeller, single stage:
Maker: Peerless , fire pump. cetrifugal
Motor pump: 0.95 inch (Pump model 10AEF20)
Engine pump: 1.38 inch (Pump model 8AEF15A)
With above data, it's very difficult for us to decide the appropriate mesh size for the pump.
Someone told me that NFPA does not allow suction strainer for the fire water pumps. Is that correct?
Regarding the water quality, it's relativeley clean.
The water is supplied from the make-up water for cooling water.
Many thanks in advance.





RE: Strainer for fire pumps
http://www.lesliecontrols.com/Handbooks/Handbooks.html
http://www.mackiron.com/
RE: Strainer for fire pumps
Ask you pump supplier for a recomendation.
If you compare the tolerable particles size against the holes of a 40 mesh I imagine that the conclusion is obvious.
Make a water analysis and check the material out of the clogged strainer. Does the analysis match with the material found? or someone forgot to flush the system.
rgs
RE: Strainer for fire pumps
Thank you very much for your interest.
How about to remove the mesh screen in the suction of the pumps and install a new strainer in the inlet of the tank as following drawing?
http://www.antlove.com/fw.jpg
<IMG SRC=http://www.antlove.com/fw.jpg>
<A HREF="http://www.antlove.com/fw.jpg">
Have a nice day.
RE: Strainer for fire pumps
The idea of filtering the water before the tank is a very good one, it avoid the typical problem of NPSH when you put a very small strainer before a pump.
I would still recommend to protect the (any)pumps against debris. The mesh size (holes) should be smaller than the Maximum passing sphere size through impeller. For sizing ask you pump supplier and check the pressure loss to determinate the required area.
Kind regards
RE: Strainer for fire pumps
Cheers!
RE: Strainer for fire pumps
6.3.4.2 The pipeline strainer shall be cast or heavy fabricated with corrosion-resistant metallic removable screens to permit cleaning of strainer element without removing driver from pump.
6.3.4.3 The strainer screens shall have a free area of at least four times the area of the suction connections, and the openings shall be sized to restrict the passage of a 7.9 mm (0.3125 in.) sphere. "
Hope this answers your NFPA question.
Regards,
RE: Strainer for fire pumps
The more you know, the less you know.