We often use Plan 14 in order to maintain the self-venting advantage of a Plan 13 and also build seal chamber pressure above suction pressure in order to suppress flashing. This can also be used for vertical turbine pumps when the seal chamber will be under full discharge pressure when running but under suction pressure when not running. If this was used, it would be necessary to pipe the discharge flush line to connect downstream of the check valve so that flow would be maintained from the discharge pressure of the companion pump. We have done this with vertical turbine pumps in condensate service on surface condensers. The discharge flush maintains positive seal chamber pressure on the pump when it is not running. This prevents air from getting drawn into the process if the seal leaks and then the pump is shut down.
Johnny Pellin