SEAL CHAMBER PRESSURE

[v7042800]

High energy barrel pump.

If you start one of these (or any multi-stage, between-bearings pump)with the discharge valve nearly shut...will the pressure developed by the impellers be transferred to the seal chambers, ie. apprach discharge pressure ? (...while the thrust bearing takes a beating)

 

[Artisi]

Probably yes, but depending on the seal arrangement it may not be a problem.

 

[JJPellin]

You have to review the design of the particular pump. Our high energy barrel pumps would not see any increase in seal chamber pressure running with a pinched or blocked discharge. But, the configuration of our pumps makes this impossible. A different pump configuration might have a different answer.

Johnny Pellin

 

[v7042800]

Thank you both for your answers. Which type of bet-bearing pump design would allow the box to pressurize?

 

[JJPellin]

We have four pumps (out of about 2000), that I think would have this problem. They are two-stage, between bearings pumps with no balance line. The inboard seal normally operates at intermediate pressure between suction and discharge. If the discharge flow was restricted, the discharge pressure would increase and so the intermediate pressure on the inboard seal would increase. The increase would be relatively slight and under no circumstances would the seal chamber pressure approach full discharge pressure. This is the only example I can think of in our refinery. In double suction, single stage, between bearings pumps, there would be no affect. In multi-stage pumps with balance lines, there would be little or no affect.

Johnny Pellin

 

[v7042800]

Thank you Johnny. I appreciate your response..!!!