Silicone 705

Features and benefits

  • Silicone 705 is a Penta phenyltrimethyltrisiloxane based fluid for producing ultra high vacuums in the range 10-9 to 10-11 mbar due to extremely low vapour pressure and back-streaming rates
  • It exhibits extreme chemical, thermal, oxidation, hydrolysis and radiation resistance.


  • Silicone 705 is intended for use where ultrahigh and ultraclean vacuum conditions are required.  The UHV characteristics particularly useful for thin film, surface technology, thermonuclear and plasma physics applications as well as electron microscopes.
  • Extreme stability and high spontaneous ignition temperature make it ideal for use in space-simulation chambers. Low vapour pressure and low backstreaming rate make cold and refrigeration traps unnecessary for pressures in the 10-8 mbar range. 
  • However with a liquid nitrogen trap ultimate pressures of 10-11 mbar can be achieved
Technical data  
Typical ultimate vacuum achievable at 20°C (mbar) 8.0 x 10-11
Vapour pressure @ 25°C (Pa) 2 x 10-11
Boiling temperature at 1.3 mbar (°C) (approx) 245
Viscosity cSt @ 25°C 165 - 185
Pour point °C -14
Flash point °C >243
Specific gravity at 25°C 1.09 - 1.10