Legend
- V. vent
- F. flushing
- LBI. buffer liquid inlet
- LBO. buffer liquid outlet
- PS. pressure switch
- PI. pressure indicator
- TI. temperature indicator
- PSL. low pressure switch
- 1. Barrier liquid refill
- 2. Diaphragm tank
- 3. If required
- 4. Diaphragm tank loading connection
Plan 53B differs from Plan 53A in that in the seal circuit pressure is maintained due to the application of external pressurized barrier liquid diaphragm tank in order to feed clear liquid to the external seal of the double system. Circulation is forced and maintained by an internal pumping ring. Barrier liquid pressure (generated and maintained by the diaphragm tank) is higher than the sealed process pressure in the gland box. Air- or water-cooled heat exchanger carries the heat away from the circulation system. Characteristics of the barrier liquid should be defined, to keep the operating conditions of the slide ring faces of the seal stable. Solution typical for double seals.
