Posted in Silicone Recycling

Diffusion Pump Oil Recycling

Another great source for recycling of silicone oil comes from oil made for diffusion pumps. A diffusion pump is used for creating high vacuums mainly in industrial applications such as thin film deposition, vacuum furnaces, protective film coatings, semiconductor manufacturing, space simulations, and much more. As diffusion pumps do not have any moving parts, it’s one of the most stable and affordable ways of producing high vacuums. Generally speaking, diffusion pumps can attain vacuums between 10e-6 to 10e-10 torr depending on the size of the pump as well as the type of diffusion pump oil used.

As stated earlier, there are no moving parts in a diffusion pump. The only moving aspect of the pump is the movement of the diffusion pump oil within. A heater is located at the bottom of the pump that heats the oil until it turns into a vapor or gaseous state. We won’t go into depth as to how a diffusion pump works, however, the vapors eventually are turned back into oil and continuously changes between these two states where air molecules are forced outside the system causing a vacuum.

Interestingly, when diffusion pumps were first introduced back in 1915, the diffusion pump oil used was derived from mercury. As mercury is poisonous to humans, this was replaced by oil made from hydro-carbons. However, as mineral based oils tend to thicken and darken when used continuously inside the pump, a problem arises where pumps became often clogged where oil changes were required relatively frequently, every several months.

The newest trend in diffusion pump oil is actually the use of silicone based oils. As silicone offers low vapor pressure and very low degradation when continuously heated and cooled, it became an ideal solution compared to hydro-carbon based oils. Nowadays, inside most diffusion pumps is a silicone based formula.

While degradation of silicone based oils is low, it is still highly recommended that the oil inside the diffusion pump be replaced at least once per year. With all the diffusion pumps being in use in the world, this left a lot of silicone oil for recycling. Luckily, we offer one of the best solutions for recycling diffusion pump oil.

The constant vaporization and condensation of silicone oil actually breaks down the oil on a chemical level. As you continue the use the oil, you’ll notice a loss of efficiency, that is, the rate of vacuum will decrease. The chemical deterioration prevents the oil from being reused as diffusion pump oil. While this is so, we have come up with a brilliant solution. Instead of trying to filter and reuse the oil for diffusion pumps, we’re now able to completely reprocess diffusion pump oil back into standard grade silicone oil that can be used in other industrial applications.

For more information about our recycling process or if you have a source for used diffusion pump oil, please make sure to contact us.