Description: Plan 74 is an external control system supplying
BARRIER gas (typically Nitrogen) at greater pressure than the
process pressure being sealed, to an Arrangement 3 dual gas seal.
Objective: Prevent process from
leaking to the atmosphere.
Remove moisture, filter the gas
and regulate the pressure to the
seal. Best for hazardous, nonpolymerizing,
fluids, light hydrocarbons and
Advantages: For processes that
do not tolerate a liquid barrier.
Can be used with LIFT OFF seal
faces that generate no heat or
wear and can have significantly
increased seal life. Lower cost
and maintenance than dual