There are a wide variety of oils or lubricants that can be used for
mechanical vacuum pumps like the HyVac pumps.
The first order of business is to understand what the oils do.
The first thing is they lubricate the pump. Because the tolerances
in these pumps is pretty tight it is important for the mating surfaces to
receive proper lubrication. The correct viscosity for the speed and
size of the pump is important. The second thing the oil accomplishes
is to cool the pump. The majority of these types of vacuum pumps are
air cooled so the oil is the "heat exchanger" that carries the
heat from the pump itself to the oil sump of the pump where the heat is
dissipated. The third and most important consideration is as a
vacuum seal internal to the pump. The oil involved is intimately
involved with creating and maintaining vacuum pressures in the pump and
Basic vacuum pump oils
Acid treated vacuum pump oils - We have one of these we have found we
call "Crystal White". It has fantastic vapor pressure numbers and
like 10-8 or 10-9 (so stated) is water white with all the nasty sulfur and
such stripped out. The problem is we have a hard time getting it.
We can get it, it just takes some extra effort and patience.
Perflorinated oils - Brand Names are Fomblin by Montiedison, Krytox by
DuPont - These oils are often used because they are chemically inert or
"un-reactive" with other chemicals. They are incredibly expensive,
heavy molecular weight and sometimes actually degrade what ultimate vacuum
the pump can obtain but if you gots to have it you gots to have it
Phosphate Esters - Has been used in oxygen rich systems in the past but
no company around will sell you this material and certify that anymore.
Silicones and Derivatives - Not very good "lubricants"
Synthetics - There are so many....