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Change the Pumps Oil


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.


11/26/2005 ęCopyright HyVac Products, Inc. All Right Reserved
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