Vent Study. Why, how to do it and how to interpret the results 

Unless you exceed the pressure rating of the seal (which is unlikely if you are coming from discharge), a high differential pressure across the process laby shouldn't damage the dry gas seal. It would simply increase the flow through the process laby, up to a choked flow condition.

There is no pressure difference in the primary seal cavity, between the process laby and the primary seal. The pressure will drop as the gas moves across the primary seal face and the process laby (or any restriction in a flowing application). The pressure entering the primary seal is a controlled parameter, controlled by the support system to a setpoint in order to maintain a specified velocity across the process laby. The pressure downstream of the process laby is approximately equal to the compressor suction pressure (if the compressor is balanced). The pressure downstream of the primary seal is approximately equal to the primary vent back pressure, which is controlled with a back pressure regulator or a check valve with a specified cracking spring pressure (usually around 5 to 10 psig in normal seal conditions).

@@rareoaq thank you that was neatly explained