API PLAN 54

It is a Pressurized external barrier fluid Circulation operating from a central pressure input source.

As flow rate is higher, it gives a better cooler efficiency. Used when operational area is at high risk i.e. Flammable, hazardous, toxic etc.

In Piping Plan 54, there is a pressurized external barrier fluid system supplying clean liquid to the barrier fluid seal chamber. Piping Plan 54 is used with Arrangement 3 liquid seals and the barrier liquid is maintained at a pressure greater than seal chamber pressure.

Barrier liquid is circulated by an external pump or pressure system. The design of the system including instrumentation, coolers, filters, and other components is outside the scope of this standard.

Piping Plan 54 is often used in services where the pumped fluid is hot, contaminated with solids, or the internal flow inducer is unable to supply a sufficient flow rate. If Piping Plan 54 is specified, carefully consider the reliability of the barrier liquid source. If the source is interrupted or contaminated, the resulting seal failures are very expensive to rectify. A properly engineered barrier liquid system is typically complex and often expensive.