Terpenes are volatile, and will end up being purged off from the original sample. Extractors can minimize this undesirable characteristic by pulling a full vacuum on the oven and locking it off before turning off the pump.
While the pump runs, it pulls solvent and terpenes into it, drastically degrading the pump oil and corroding the pump. This is one of the main reasons a pump will start to lose strength. Clean oil allows the pump to operate correctly and pull to the deepest vacuum it is rated for.
What is a cold trap?
A cold trap, sometimes referred to as a terp trap, is placed between the vacuum ovenand the vacuum pump. The terp trap will super-cool the air coming through it, and will recondense any terpenes that get off-gassed as a result of the purging process.
This will prolong the life of your vacuum pump, and allow you to go longer between oil changes by preventing contamination.