Backflow through centrifugal pump

[david6245]

Hello,

I am in the process of sizing a RO in a 1" warm up line around the discharge check valve of a pair of hot (415 deg F) condensate pumps. I have a somewhat simple question: is backflow through these pumps in this type of application an issue? The flow I calculated for this warm up line is 7 gpm vs a pump capacity of 1500 gpm. Are pumps designed to handle back flow up to a certain limit?

Any info would be great.

Thank you,

David

 

[Artisi]

Can't see any issue with backflow. Pumps are not designed with back flow as a consideration but are more than capable of tolerating backflow within certain limits but in your case, 7 gpm probably won't ever be noticed.

 

[JJPellin]

Back flow through a pump would not normally be a concern. As long as the rate of back flow is not great enough to roll the pump over in reverse, then I see no significant potential for harm. If the flow were to roll the pump over, it could only be a problem if the reverse rotation was too slow to provide proper lubrication to the bearings. It would also be a problem if the pump uses dry gas seals which are often rotationally specific. Spinning in reverse, the seal faces will not lift off and the faces will be damaged with some designs. But, a flow of 7 gpm in a pump rated for 1500 rpm should not be capable of reverse rotation.

Johnny Pellin