3 replies to this topic

[stu]

Dear All,
I am in need of one clarification regarding pump suction line reducer.
Is it the reducer compulsory required in the pump(centrifugal) suction line, while the line size and suction nozzle for pump is same.
Please explain.
regards,
Stu

[ankur2061]

Dear All,
I am in need of one clarification regarding pump suction line reducer.
Is it the reducer compulsory required in the pump(centrifugal) suction line, while the line size and suction nozzle for pump is same.
Please explain.
regards,
Stu

Stu,

I have written a company standard for a reputed O&G company in middle east titled 'Process Design Criteria' where in the liquid line sizing criteria for pumps I have mentioned the following:

quote:Pump suction lines shall not be smaller than pump suction nozzle. Therefore, eccentric reducer at pump suction is acceptable provided that the available calculated NSPHa (with pressure loss in the reducer) remains acceptable regarding the required NPSHr.:unquote

Hope this helps.

Regards,
Ankur.

[Andrei]

I concur with Ankur, the pump suction line reducer requirement is according to each companies’ standard and in some big projects it's a project standard. It is not actually the reducer requirement defined, but the line velocity and/or pressure drop.
As a rule of thumb for centrifugal pumps the suction and discharge lines are at least one diameter step larger than the pump nozzles. It is not working absolutely everywhere but in a lot of cases. And usually the reducer is placed immediately near the pump, both suction and discharge.

[fallah]

Dear All,
I am in need of one clarification regarding pump suction line reducer.
Is it the reducer compulsory required in the pump(centrifugal) suction line, while the line size and suction nozzle for pump is same.
Please explain.
regards,
Stu

Pump nozzles sizing is in vendor scope and determined based on customer requirements such as head,flow,...and other parameters e.g. reasonable NPSHr

Discharge and suction lines sizing is in process disign scope and determined based on NPSHa,velocity limitation,....

Pump nozzles and suction/discharge lines should be connected by reducers, if they are different on their size.