LF Purge Pac

Low-Friction™ technology decreases rod temperatures, enabling purged and buffered packing cases to last longer.

Patented* Low-Friction Design

The Cook Compression “AL” ring is known throughout the industry as state-of-the-art sealing technology for purging or buffering environmentally sensitive packing cases. Cook Compression LF Purge Pac assemblies build on this proven technology to take purge and buffer seal performance to the next level.

Developed by Cook Compression engineers, Low-Friction (LF) technology uses springs and pressure plates to effectively side-load standard seal rings without the increased heat generated by a wedge-type ring.

Reduced Rod Temperatures

Field data and internal testing demonstrate that LF technology reduces rod temperatures by 50°F (27.8°C) or more compared to the AL ring.

Simplified Installation and Maintenance

The convenient and innovative cartridge design of the LF Purge Pac assembly simplifies installation and maintenance by eliminating the need to handle small, loose parts.


An LF Purge Pac assembly can be retrofitted to most packing cases with at least 1.33 inch (33.78 mm) of axial space. If space is limited, the axial dimension can be reduced to 1.19 inch (30.23 mm) by substituting thinner seal rings.


  • Extends seal ring and packing case life
  • Forms a virtually leak-proof chamber for purge or buffer medium
  • Retrofits to most packing cases
  • Accommodates standard size seal rings
  • Cartridge design for trouble-free field maintenance

*US Patent #8,25,372

LF Purge Pac Information Sheet

LF Purge Pac