Plan 52 is used with Arrangement 2 seals, with a contacting wet containment seal utilizing a liquid buffer system. It is normally used in services where process fluid leakage to atmosphere must be minimized and contained. It is also used in applications where the process may solidify in contact with atmosphere or in applications where additional heat removal from the inner seal is required. The buffer liquid is contained in a seal reservoir which is vented to a collection system, thus maintaining the buffer system pressure close to atmospheric. Buffer liquid is circulated to and from the reservoir by means of an internal circulating device.

A Plan 53A system consists of dual mechanical seals with a barrier liquid between them. The barrier liquids contained in a reservoir which is pressurized above the seal chamber pressure. Inner seal leakage will be barrier liquid leakage into the product. In Plan 53A there is a pressurized external barrier fluid reservoir supplying clean fluid to the barrier fluid seal chamber. The barrier liquid reservoir is pressurized by an outside source, typically the plant nitrogen system, and it is maintained at a pressure greater than seal chamber pressure.

In Plan 75 there is a containment seal chamber leakage collection system for condensing or mixed phase leakage on Arrangement 2 seals. Plan 75 systems are typically used on unpressurized dual seals, which also utilize a dry containment. It is intended to perform the collection function for pumped fluids that may form some liquid (condense) at ambient temperature.They may be used with a buffer gas (Plan 72) or without a buffer gas (Plan 71).

In Plan 72 there is externally supplied buffer gas for Arrangement 2 seals. Buffer gas is maintained at a pressure less than seal chamber pressure. This plan may be used alone or in conjunction either with a Plan 75 or Plan 76. The buffer gas can be used to sweep inner-seal leakage away from the outer seal to a collection system and/or dilute the leakage.

Seal Flush coolers shall be arranged with the seal Flush fluid on the tube side and the cooling water on the shell side. It shall be arranged for complete draining and venting of both the water and process sides. The air cooler shall be constructed with finned tubing and arranged with the seal Flush fluid on the tube side.

In Plan 76 there is a containment seal chamber drain for non-condensing leakage on Arrangement 2 seals. This plan is used if the pumped fluid does not condense at ambient temperatures. They may be used with a buffer gas (Plan 72) or without a buffer gas (Plan 71)