Supply pressure to a Plan 32? 1

[justabitconfused]

Complements of the season to you all!

If you have an ASME B73.1 pump specified with a Plan 32 seal arrangement, how much above the pump discharge pressure does the Plan 32 water supply pressure typically need to be please? I have a figure of 2 Barg in my mind. Thank you.

 

[Pumpsonly]

2 bar is about right,but check the seal box pressure.

 

[justabitconfused]

Thanks, I thought 2 Barg above discharge pressure was a bit high, but thanks for confirming my thoughts. You mention seal box pressure, but as a Plan 32 feeds into the pump behind the impeller, I am basing my Plan 32 feed pressure on pump discharge pressure rather than packing box pressure. Thanks again.

 

[poppeye]

Plan 32 uses external flush into the seal chamber (stuffing box) does your impeller have hydraulic balance ports from the inlet eye to the rear of the impeller? If so the stuffing box sees a slightly higher pressure than the pump inlet pressure. A good rule of thumb is 25psig above stuffing box pressure to ensure that there is adequate pressure to maintain flow through the stuffing box and out into the cavity behind the impeller. The use of a tight fitting throat bushin at the bottom of the stuffing box will ensure holding pressure and maintain flow velocity. If you don't know what the stuffing box pressure is, use one of the packing lubrication ports to access for a pressure gage reading and adjust accordingly.