Vacuum pump oil is pretty much just mineral oil (unless you're doing oxygen service, but that's a different problem). But, don't use anything other than vacuum pump oil if you want to actually pull a vacuum. Vacuum pump oil is specified to have very low outgassing so the partial pressure form the oil itself is low.
Oil-free rotary pumps can run continuously both at atmospheric pressure and at the highest vacuum. However, they cannot be used when the aspirated air contains moisture, oil or other liquids traces. At a certain pressure, the rotary compressors benefit of supplying air without pulsations.
Vmaxol and Duratex brand vacuum pump oils have an indefinite shelf life under the right conditions. As long as the container has not been opened or left outside, there should not be a reason for the lubricant to deteriorate.
Remember that the vacuum pump dries the system out by pulling water out as a vapor; if you shut the pump down and don't change the oil while it is warm, the water and oil will separate—water on the bottom, oil on the top.
The 7 Golden Rules of Vacuum Pump Maintenance
- Rule 1: Read your manual and check the oil regularly.
- Rule 2: Warm up the pump with the inlet blocked.
- Rule 3: Never block a pump outlet.
- Rule 4: Use an inlet cold trap to protect the pump from corrosive vapors.
- Rule 5: Use gas ballast (continuous purge) when working with condensable vapors.
Replace the OIL DRAIN cap. Remove the OIL FILL cap, and fill the reservoir with new vacuum pump oil until the oil just shows at the bottom of the sight glass. The approximate oil capacity of the pump is 15 ounces. 5.
For example, refrigerant R-22 has a boiling point of 45°F at a pressure of 76 psig. It's boiling point changes only as it pressure changes. After a liquid has changed to a vapor, any further heat added to the vapor raises its temperature.
Smoke or mist out of your exhaust indicates there is a volume traveling through the pump; if you see a constant flow of mist out of the exhaust, and you think you have exhausted your vessel or chamber that you are pumping down, it may indicate there is a leak somewhere into the pump, or that the gas ballast is in the
Paraffinic base mineral oils are suitable for the majority of vacuum pump applications in industry and science. The typical oil used in a large rotary piston vacuum pump is a mineral oil that has been through a distillation process to reduce its vapor pressure.
Vacuum Oil and Standard Oil of New York (Socony) merged in 1931, after the government gave up attempts to prevent it. In 1955, the company became Socony Mobil Oil Company.
Vacuum pump oil is extremely hygroscopic (moisture absorbing) so starting fresh will make things go a lot faster. Moisture destroys vacuum pump oil by increasing its vapor pressure so much that a high level of vacuum cannot be created. The pump cannot develop a higher vacuum then the vapor pressure of its sealant.
What happens to oil exposed to vacuum? Thanks to the zero pressure to keep the liquid's molecule together, a liquid exposed to vacuum will boil (sublimates), whenever it's temperature is above the freezing point. Mineral oil is a mixture of hydrocarbons. It will slowly evaporate away when exposed to a high vacuum.
Different types of pumps for these vacuum ranges can then be divided into Primary (Backing) Pumps, Booster Pumps and secondary (High Vacuum) Pumps: High, very high and ultra-high vacuum pressure ranges. There are two basic categories of vacuum pump: Gas Transfer Pumps and entrapment or capture pumps (Figure 1).
Regardless of their design, the basic principle of operation is the same. The vacuum pump functions by removing the molecules of air and other gases from the vacuum chamber (or from the outlet side of a higher vacuum pump if connected in series).
Since both types of pumps require same characteristics of vacuum oil so the same vacuum oil is used for both these types of pumps.
Inches of mercury of course, that's the usual measurement unit for vacuum. About 30" is the maximum you can get anyway. At work we have a vaccum pump, it never gets above 15" and when it's in use it runs continuously for hours.
What is a gas ballast? Vacuum pumps designed for pumping vapours are generally equipped with a 'gas ballast' control. The gas ballast allows a controlled amount of gas, generally air from outside the pump, to be introduced into the pumping mechanism.
PAG oil, or Polyalkylene Glycol, is a fully synthetic hygroscopic oil specifically designed for automotive air conditioner compressors. It is used in R-134a air conditioning systems to lubricate the compressor. These numbers refer to the viscosity of the oil, similar to 10W30 oil.
Why should only oil designed for vacuum pump operation be used in vacuum pumps? Oil that is not intended for use in vacuum pumps has a much higher vapor pressure than vacuum pump oil, and will limit the amount of vacuum the pump can produce. It is a waste of time to pull a vacuum on a system that leaks.
