why do you think mercaptoethanol
Ive gotten that one a few times!
terpenes are highly reactive, so heat and O2 cause a lot of changes. When these compounds make it to your pump they are dissolving into the pump oil. You should expect to get this nasty smell when you break your vacuum and all that air flies through your pump and out the exhaust.
If you are smelling this all the time while running you definitely should check for leaks in your system, change your pump oil. drain it, fill it up to the MIN level, run for 5-10min, drain, repeat that, and then refill the oil to operating levels.
a series of cold traps (two, three is even better, the coldest closest to your pump) will help prevent these compounds from making it to your pump oil and building up as quickly, but honestly your oil will eventually pick up these compounds over time.
You can also buy some âflushing solutionâ from someone like www.duniway.com/part/dsff-1
These compounds fouling your oil will also reduce the effectiveness of your pump to pull deep vacuum. so keep it clean, protect it via serial cold traps, and change the oil when the pressure indicates.
Also, you should probably vent that pump exhaust to the outside, or to an exhaust fan.
Sorry, that was a harsh reply.
Its something I once worked with for a long time. The odor is quite distinct.