|The single best suggestion we
can offer a user of vacuum pumps from all our experience, is to CHANGE YOUR OIL on a regular
basis. What the heck is "regular"? After each use, at the
end of the week, once a month, once a year so much depends on the
application and system set-up. We have seen and heard most of
it. It is a regular topic of conversation. Suffice to say many problems and potential problems can be averted by this simple maintenance
practice. We probably answer more questions and solve more problems
relating to this issue than any other one.
This suggestion is even more
important if the user is planning to store a pump after use for an extended period of
time. Vacuum pump oils for the most part have some basic chemical elements as part of
their physical make-up. Generally all petroleum oils have sulfur to one degree or another.
If your pump gets water contamination in it, the water will eventually combine with the
sulfur to form sulfuric acid. This acid will attack
your pump. In vacuum pumps, as in your car to a lesser degree, the oil, barring a change,
will oxidize over time and use, creating a breakdown in the oil, and releasing the sulfur
to make acid. The oil will become darker in color and start to sludge up. Oxidation and
acidification of oils in service are logarithmic in nature, meaning when the oil starts to
go bad, they feed on themselves in an exponential manner.
For the most part mechanical vacuum pumps
from HyVac or any manufacturer are made from cast
iron which will actively rust up given contact with acidic solutions. This will then cause
your pump to freeze or lock up. We have seen pumps come in to HyVac for repair where you
open the pump case and the oil actually slumps out of the pump it is so oxidized and
degraded. Some pumps are marketed as "corrosion resistant";
do not be deceived. We have prepped pumps for this service we do not
subscribe to the concept. "Resistant" is a great term that
assures nothing but most assuredly is a great marketing ploy.
How often to change your oil depends on the application. Some
applications lend themselves to severe contamination and introduction of acidic
constituents to the pump. If you are evacuating water from samples or acids like glacial
acidic acid or any of your primary acids you will have to monitor your oil and probably
change it frequently. Use of inlet traps (cold) or external oil filtration systems can
minimize or correct contamination. Use of the vacuum pumps gas ballast valve to purge
condensable contamination during pump down. Generally this is a trial and error process.
testing can be accomplished initially to determine how quickly this contamination is
occurring. The pump oil you would use in a new state has what is know as a neutralization
number, neut. #, or total acid number (TAN). This value can be derived with physical
chemistry to determine later, after use, acidic levels and compare against the original
values. Use of correct litmus or pH paper can also give indication of the oils acidity
starting with new oil and comparing it at various evaluation points.
Learning and documenting your specific situation will only help you save
money over the long haul. It also gives us more information when we try and
find solutions for you.