|Most HyVac Products, Inc. vacuum pumps are shipped and contain a
feature known as the gas ballast valve. This is viewed as a black adjustable knob on top
of the pump.
Often in vacuum work, the user will get water vapor,
solvent vapor or other bad contaminants as part of the gas stream being evacuated from the
vacuum chamber. These contaminants come over because they have turned into a gas molecule
from a liquid molecule under "X" vacuum pressure and the pump pumped them out of
the system. They then travel to the pump and turn back from a gas to a liquid in the pump
All liquid chemicals have a value known as vapor pressure. This vapor pressure
is a function of physical chemistry law. The basic formulae is PV=nRT. I could get into an
explanation more detailed here, but suffice to say that as a result of this formula, water
will boil at room temperature when a vacuum pressure of roughly 29.5" mercury vacuum
is achieved. When water boils it is turning from a liquid into a gas. All chemicals have
this feature, just at varying temperatures and pressures based on their molecular
It is possible to throughput some of these contaminants from your system and
through the pump and that are where the gas ballast valve comes into play. If you do not
require high vacuum less than say 300 micron for instance, then you can open up the gas
ballast valve during the evacuation procedure and get some of these bad molecules out of
the pump through the exhaust port of the pump. Remember also if they are coming out the
exhaust they potentially are entering your workplace. This may pose a hazard either health
based or fire based. If you are looking for better vacuum pressures, the valve is
adjustable. This feature is not the total answer; it helps, but should not be considered
the solution in problem applications with lots of contaminates.
If and once the pump is contaminated you can again use the gas ballast valve to
assist in purging some of these contaminants from the vacuum pump oil in which it now
resides. Close the pump inlet port off to full vacuum and allow pump to run/actuate with
gas ballast valve in open position. This again will help purge the pump. Take a long lunch
or let the pump actuate overnight with the valve open. Care again should be considered to
the exhaust stream. If the pump is "smoking" or exiting oil mist in good
quantity, you may come in the next morning to a room full of oil mist. Piping to a hood or
using a coalescing filter like the HyVac Capture filters can help eliminate this problem
If you have big problems in this area, or if you are always finding contaminants
in your oil, you probably need a different solution and should call us.
It is common during operation of the pump with
the gas ballast open for there to be
seen oil mist or "smoke" coming from the exhaust of the pump. Continuous duty at
these pressures generally causes the user to desire a HyVac Oil Mist Eliminator or HyVac
Capture filter available from us for most vacuum pumps.
If you have no problem with contaminants you should use pump with the gas
ballast valve closed. We consider this normal operation.
Any other questions please feel free and call.