3 replies to this topic

[kasri]

Dear sirs,
Please calrify the following querry .
For centrifugal pump if the flow reduces the developed head will be high for the same rpm,same liquid.
Then how about reciprocating pump.For ex.
A pump( centrifual/reciprocating) is designed for 5 m3/hr , suction pressure: 3 barg , discharge pressure 10 barg.( ie. pressure differential=7 barg).
(1)If the suction flow reduces , the developed head will be increased for centrifugal pump;similary what happens if the suction pressure reduces to 1 barg( for the same flow of 5 m3/hr), is it develops the discharge pressure of 8 barg( 1+ differential pressure 7 barg).
(2)In case of reciprocating pumps,if the suction flow reduces , what will be the outlet pressure is it increase( driver speed same as 5 m3/hr);similarly what happens if the suction pressure reduces to 1 barg( for the same flow of 5 m3/hr & driver speed same as 5 m3/hr), is it develops the discharge pressure of 8 barg( 1+ differential pressure 7 barg).
Please clarify me eventhough I read with theoretical sentence, it is better to understand through numeric values.

Regards,
Kasri

[breizh]

Kasri ,
I invite you and others to open this link where you can get a lot of very good information about the centrifugal pumps .

http://www.gouldspum...at_pf_0001.html

You should be ablr to get additional info udsing search button , top right!

Hope this helps

Breizh

[Erwin APRIANDI]

Dear Kasri,

You can browse thruu this site

http://www.driedger...._cp/CE1_CP.html
and
http://www.driedger....dp/CE2_PDP.html

Hope you it clear up your problem

[djack77494]

One important point to make here. The term head is often used in refering to the performance of a centrifugal pump. It should NOT be used when refering to a positive displacement pump. Dynamic pumps transfer kinetic energy to the pumped fluid. The energy imparted to the liquid is such that the liquid can be driven to a certain height for a given flowrate. For example, if you connect a centrifugal pump to a vertical pipe of a length just long enough that the liquid makes it to the top of the pipe but does not overflow, then the discharge head of the pump is the height of the pipe. The pump only incindentally produces pressure. If the pump were a pressure producing device, then it would put out a fixed pressure for a given flow, independent of the liquid being pumped. It does NOT operate that way. Instead, it will generate a fixed head for a given flow. While the discharge pressure changes as the liquid's density changes, the discharge head does not change. These characteristics, however, do not apply to PD pumps.