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. Replacement for and equivalent to Dow Corning DC-702. Sold as DS-702 and Invoil 702 elsewhere.
MT-704 and MT-705 are available in separate listings.
| SPECIFICATION | MT-702 | MT-704 | MT-705 |
| 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 gallon | $375.00 | $475.00 | $595.00 |