D C Silicon Diffusion

Dow Corning silicone oils are designed for fast pumping of large volumes of gas or vapour in high vacuum production operations.

Performance advantages compared to other diffusion pump oils:


  • Shorter conditioning runs/faster pumping speeds than organic fluids
  • Minimal backstreaming
  • Longer service life, resistance to deterioration or contamination
  • Cleaner systems and less required maintenance because of low migration rates and resistance to breakdown or decomposition.
  • Faster cycling, reduced downtime, and less frequent fluid replacement because the recovery rate after exposure to air at operating temperatures is much faster than that of organic fluids.
  • Resistance to oxidation and hydrolysis by water vapour.
  • Resistance to radiation.


  • Full compatibility with rubber seals.

Value advantages:
Dymar Chemicals is the lowest cost in-Canada source for the Dow Corning diffusion pump oils and high vacuum grease – we are price competitive compared to inferior-quality clone products from other sources.

We inventory for fast and friendly service, and eliminate the hassles of outside-Canada ordering.

Our fluid recycling program provides a substantial savings for you through a reduction in new oil purchases and oil disposal costs.


Complete Product and Cross Reference Guide

Dow Corning 702: Viscosity at 25 ° C – 45 cSt
Vacuum range: 10- to 10- torr, 10- to 10- torr in vapour ejection pumps.  Thermally stable.  Resists oxidation at high temperatures.  Your lowest cost general purpose fluid.
Primary uses:
For fast pumping of large volumes of gas or vapour inproduction applications.


Dow Corning 704: Viscosity at 25 ° C – 39 cSt
Vacuum range: 10- to 10- torr untrapped , or 10- torr trapped.  Single-component fluid with high phenyl content. Chemically inert. Free of impurities. Oxygen, radiation and explosion resistant.
Primary uses:
Tough, rugged applications. It offers quick pumpdown, even exposure to air at operating temperatures.


Dow Corning 705: Viscosity at 25 ° C – 175 cst.
Vacuum range: 10- to 10- torr untrapped.
Single-component fluid with low vapour pressure and backstreaming rates.  Thermally stable. Resistant to oxidation, hydrolysis, and radiation.
Primary uses:
For producing ultrahigh and ultraclean vacuum. Man-rated space simulation chambers.


High Vacuum Grease: Service temperature range: -40 ° C to 204 ° C.
Good lubricating and sealing ability. Low volatility. Excellent resistance to water, chemicals, high and low temperatures.
Primary uses:
Seals and lubricates chemical processing equipment, plug, control, and fire extinguisher valves, flow meter bearings, ceramic plug cocks, vacuum and pressure systems, water treatment equipment, synthetic rubber gaskets and O-rings.

Dymar’s fluid recycling program:
Reduce your operating costs by recycling – reduce new oil purchases and oil disposal, and achieve better vacuum performance by using clean, rejuvenated oil instead of deteriorated product. The recycled fluid can be confidently reused as a direct replacement for new – all depleted oil components/additives are fully restored.. 40 lbs/ 5 (U.S.) Gallons of Dow Corning or a competitive equivalent is the minimum amount required for recycling, but Dymar’s fluid purchase program serves the smaller volume user through our collection of smaller oil quantities. The pre-recycling condition of the oil determines its’ value.

Advantages to recycling through Dymar:
Complete lab testing of the recycled oil. Fast turnaround time, cheaper recycling costs, and fewer shipping and customs hassles. The fluid returned is of consistently high quality and performance.