Purged Packings
Purge packing refers to a packing
case modified to accept an external purge pressure 15 to 20 psi above
the primary packing vent/drain pressure with no more than 5 psi external
system back pressure. The purge gas must be sweet natural gas, propane,
or an inert gas, such as nitrogen. The purpose of purge gas is to block
and contain hazardous, toxic, flammable or corrosive gases, and to prevent
such from entering the compressor frame where damage to the running gear,
or personnel safety hazards can occur.
Packing case materials are cast
iron and steel. When
steel is used, it is heat treated to be in compliance with NACE. Garter
springs are 316 stainless steel, for both sweet and sour applications
(acceptable for sour service based upon acceptable field experience).
See also "Packing Leakage"
and "Purge and Vent
Arrangements".
Ariel Corporation Application Manual
3 May 2005