stuffing box pressure calcs

[upm]

Gents,
Any idea how to estimate the stuffing box pressure for horizantal/vertical multistage pumps? need to verify the vendor calcs
upm

 

[longeron]

I assume the horizontal pump is between bearing.

Horizontal:
The seal chamber on the suction side will usually be right at suction pressure. The seal chamber on the discharge side is likely between suction and discharge, where depends upon the use of a balance line. If a balance line is not used the pressure should be the sum of suction pressure and half the difference between discharge and suction pressure.

Vertical:
Without a balance line, the seal chamber should be at discharge pressure.

I hope this helps.

 

[upm]

Thanks longeron
I have a horizantal overhung pump single stage, i used the equasion:
Ps+0.25*DH=Ps/b, is this correct?
for vertical pumps it is always the same as the discharge presuure?
upm

 

[longeron]

Usually a single stage horizontal pump's stuffing box pressure can be found by

Pbox=Ps + .1(Pd-Ps)- but it depends upon the impeller type. Most Durco pump curves have a stuffing box curve at the bottom right of the graph.