Circulation pump

[flamearrow]

Hi everyone,

We have a problem with our circulation pump of the firewater tank. the rated power on the plate shows 11 kw,
while our reading given 4.7 kw (8.5 R-Y-B, V-L-L -396v) & (Pump 35 l/s & 15.4 m and suction lift of 1.6m, dH-0 m)
we have enhanced the suction discharge lines as 8 nos of foot valves (PN16)in the suction of 150mm and 12 nos MFP nozzles of 50mm connected in 100mm discharge line in order to cover the entire tank water for circulation.

Besides the flow reading was less as 21 l/s in fully opened line and the discharge pressure in the downstream was 6-7 psi.

NPSH available has been proven above the required to aforementioned design. ( NPSHa =3.9 m, NPSHr =2.1m )

Is the pump performing under and cause cavitation? could anyone diagnose the problem and advise me what is lacking
Please

 

[Artisi]

Have you checked for correct direction of rotation?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

Type days is a bit confusing and would benefit from a sketch, but you seem to have a lot lower inert head than the design, hence lower other head and hence less flow and less power. You day 11KW on plate. Plate of what? pump or motor? I get pump shaft power to be about 8KW

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[flamearrow]

Thank you gentlemen for all your replies.
rated power from motor plate. yes we realized that the available head even we get positive answer by calculation theoretically, it must have affected the capacity.
Is the PN (PN16) rating of the foot valve playing any role, I mean, the spring is too stiff to be lifted fully?

 

[flamearrow]

of course pic will postulate more than words. please find attached fwt.rar for dwg and data

 

[flamearrow]

Direction of Rotation is correct. What type of flow meter will suit to our system, to measure accurate flow.
Magnetic or any mechanical type such as turbine

 

[Artisi]

Miko123. I can not open your dwg / file .

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[flamearrow]

Artesi, Sir, it is all PDF format files zipped to RAR. how could I help you to open?

 

[LittleInch]

Just post them as a zip file or individually. .rar is not installed or supported on many systems and I can't get it to open without security warnings

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[flamearrow]

Dear gentlemen

please find attached zip file format. sorry for the inconvenience.