1 reply to this topic

[SyedAhmed]

Dear All

 

I am doing the hydraulic of the existing pump suction line.

 

Case in detail

 

There are three pumps connected in series. One is centrifugal booster pump and the other two is PD pump. Booster pump discharge is the two PD pump suction. Booster pump is operating @ 220 USGPM @ 45psig. Distance between the pumps is 200ft. Calculated NPSHa is -630 ft. If we operate one PD pump than it works perfect but when two PD pumps works simultaneously than the pumps start cavitation. I propose to reduce the distance between the pumps and increase the line size but client want to add the pulsation dampener.

 

I went through the API 14E for pulsation dampener to reduce the acceleration head but the example has given to reduce the pump suction length to 15 x nominal diameter. I need to know that if I have 200ft distance between the pumps with 4” line size so Length use in acceleration head will be 5ft. In that case NPSHa increase to +48ft. Its mean API calculation neglecting the acceleration head of 215ft line and only 5ft line acceleration head will be use for the calculation of NPSHa.

 

Please help me to understand this as I believe the acceleration head of upstream dampener will also be included in the NPSHa calculation because this will also affect the Pump suction.

 

[fallah]

Hi,

 

A simple sketch of the system would help us out to provide better assistance...