API Plan 74 Barrier Gas
API Plan 74 supplies a pressurized barrier gas from an external source between the inboard and outboard seals. For reliable operation, dual pressurized gas seals require a constant supply of clean, dry gas, typically nitrogen. The seal support panel contains a coalescing filter to remove any moisture and particulate present in the supply of plant nitrogen. A pressure regulator on the panel regulates the nitrogen to at least 25 psi (1.7 bar) above the seal chamber. Used in applications where process leakage cannot be tolerated, the system is designed to allow a small amount of nitrogen to leak into the process fluid. Any leakage past the outboard seal will be pure nitrogen. An optional flow transmitter located on the gas supply panel monitors excessive leakage in the event of a seal failure.
Panel and kit shown with some optional components.
This plan:
- Supplies the gas seal with a clean, dry buffer gas, typically nitrogen
- Prevents process leakage to atmosphere in the event of a inboard or outboard seal failure
Plan 74 is available as an assembled panel. The associated field installation kit for use in connecting the panel to your system is also available. Panel contents may include:
- Swagelok tube fittings
- 43G series ball valves
- V series 2-valve manifold
- R series relief valves
- CH series check valves
- FC series filter
- G2, M1, and M2 model flowmeters
- KPR series regulator
- PGI series gauges
- Swagelok pipe fittings
- Pressure transmitter
- Pressure switch
- Mounting panel
- Brackets/miscellaneous hardware
See page 59 of the Mechanical Seal Support Systems Application Guide for additional details and ordering information. Contact your authorized Swagelok sales and service center for information on optional components.