Silicone Diffusion Pump Oil

702, 704 & 705 + Dow Corning High Vacuum Grease

Dow Corning no longer offers DC-702, DC-704, and DC-705 for sale to the general market. Midwest Tungsten has filled the gap by offering private label 702, 704, and 705 chemically equivalent products in gallon containers and 500 cc bottles. Ask for our MT-702, MT-704, or MT-705. All are in stock for immediate delivery.

702 Pump Oil

MT-702 diffusion pump fluid is a general purpose fluid designed for fast pumping of large volumes of gas. It is used to produce vacuums in the range of 10E-5 to 10E-7 torr. It is also used in vapor ejector pumps that attain vacuum of 10E-4 to 10E-5 torr.

download SDS  Download MTS 702 SDS

704 Pump Oil

MT-704 diffusion pump fluid is a single component fluid for high vacuums of 10E-6 to 10E-8 torr, untrapped or 10E-10 to 10E-11, trapped. It performs well in tough, rugged applications and offers quick pumpdown, even after exposure to air at operating temperatures, although this is not recommended.

download SDS  Download MTS 704 SDS

705 Pump Oil

MT-705 diffusion pump fluid is a colorless to light straw, single component for ultrahigh vacua in the range of 10E-9 to 10E-10 torr untrapped and 10E-11 torr trapped. The vapor pressure and backstreaming rate of MT-705 Diffusion Pump Fluid are low enough that use of traps or refrigeration may not be necessary for all ultrahigh and ultraclean vacuum applications. It has the highest phenyl content of all silicone diffusion pump fluids, and hence, the best resistance to radiation. Additionally, MT-705 has a high spontaneous ignition temperature.

download SDS  Download MTS 705 SDS

Dow Corning High Vacuum Grease


MTS still sells Dow Corning High Vacuum Grease. A 150 gram (5.3 oz.) tube is $30.00.

Check out our MTS TIPs:

  1. What is a diffusion pump and what is the purpose of diffusion pump oil?
  2. Tips for Diffusion Pump
Molecular Description Mixed phenylmethyl dimethyl cyclosiloxane Tetramethyl tetraphenyl trisiloxane Pentaphenyl trimethyl trisiloxane
Color Clear Light Straw Clear/Light Straw
Ultimate Untrapped Vacuum (torr) 10E-5 10E-7 to 10E-8 5 E-9
Ultimate Trapped Vacuum to 10E-11 to 10E-11
Extrapolated Vapor Pressure at 25 ºC 1 x 10E-6 2.1 x 10E-8 5 x 10E-10
Specific Gravity at 25 ºC 1.07 1.07 1.09
Viscocity at 25 ºC 45 39 175
Flash Point, open cup (ºC) 193 221 243
Boiling point, 0.5 torr (ºC) 180 215 245
Typical Boiler Temperature (ºC) 190 220 260
Heat of Vaporization (kcal/gm mole) 21.7/190 ºC 25.5/200 ºC 28.2/250 ºC
Surface Tension (dynes) 30 37.3 36.5
Molecular Weight 484 546
Price per 500cc
$135.00 $170.00 $200.00
Price per gallon $375.00 $475.00 $595.00

Buy now – Purchase Pump Oil Online

diffusion pump oil

Midwest Tungsten Service, Inc. has made every effort to verify the information presented on this page is accurate and reliable. It is the responsibility of the user, however, to determine fitness for use. DC 702 and DC 704 are products and trademarks of the Dow Corning Company.