Low-Volatility Phenyl Silicone Oil is the Preferred Choice in the Vacuum Industry: Summary of Practical Use Issues
Silicone Diffusion Pump Oil IOTA 705-IOTA

1. The low-volatility phenyl silicone oil has significant advantages and the popularity of replacing the medium in vacuum equipment is on the rise.
In scenarios such as vacuum coating, vacuum heat treatment, and molecular pump diffusion oil, strict requirements are imposed on the saturated vapor pressure and high-temperature volatility of the medium. The low-volatility phenyl silicone oil has strong thermal oxidation stability and low out-gassing at high temperatures, making it less likely to contaminate the chamber and workpiece. It can reduce internal fouling in the vacuum chamber and decrease the frequency of equipment cleaning. More and more vacuum process ends are beginning to evaluate the replacement of the medium.


2. Will phenyl silicone oil in a vacuum environment release contaminated products?
Answer: Qualified low-volatility brand phenyl silicone oil has a very low risk of vaporization at the rated temperature in a vacuum environment. If a brand with inconsistent phenyl content and high volatility is selected, or if it is used at excessively high temperatures for a long time, there will be volatilization migration, contaminating the chamber and workpiece. When selecting, pay special attention to the saturated vapor pressure indicators and match the vacuum level.

3. Can filtered used phenyl silicone oil be reused?
Answer: Filtering can only remove solid particles, but it cannot remove small molecules and polar impurities produced by oxidation. If the oil has significantly changed color and viscosity has increased, even after filtering, the oxidation products still exist. Continuing to use it will quickly contaminate the vacuum system. Only clean and unoxidized oil can be limitedly reused after precise filtration and meeting the indicators.

4. What should be done if phenyl silicone oil mixes with other oil products in the vacuum system?
Answer: Mixing different types of oil products will destroy the original thermal stability and vacuum properties, causing a significant increase in the saturated vapor pressure and directly resulting in the inability to achieve the required vacuum level. Once there is mixed oil, it is recommended to completely empty the system, clean the oil circuit of the chamber multiple times, and replace with brand-new phenyl silicone oil. Do not continue to run with mixed operation.