Protection against various aggressive vapors, which may attack the pump or pump oil
Prevent high molecular weight vapors (such as might arise in a resin treatment plant), from reaching the pump. These vapors could cause lacquering or clogging
The standard sorbent (activated charcoal), has relatively high trapping properties (absorbs around 25% of its own weight), even when large amounts of water vapor are being pumped
When filled with activated alumina on two-stage pumps, backstreaming of pump oil can be controlled