The AVA-PBU pressure balanced unitized design is the latest concept in shaft seals. The
AVA-PBU was developed to extend packing life in conventional applications. However, it has
found use in all services from non-lube air to 50,000 PSI compressors handling polyethylene.
Each ring operates on the principle of balancing the pressures around the seal to minimize
the downward force of the piston rod. Frictional forces are reduced considerably. In
applications where filled PTFE materials are utilized, there is less chance that the PV
limit (temperature/pressure limit) of the PTFE will be exceeded because of reduced
frictional heat.
