Product recirculation from seal chamber to pump suction via a flow control orifice.
1. Provides continuous vent for vertical pumps.
1. Wherever Plan 11 is not usable due to low-pressure margin between discharge and seal chamber pressure.
2. Used in vertical pumps.
1. Check margin between seal chamber pressure and suction pressure.
2. Orifice size should be at least 1/8” (3.2mm).