SPI Supplies 705 Silicone Diffusion Pump Fluid, Pentaphenyl Trimethyl Trisiloxane

The SPI-704 and SPI-705 silicone diffusion pump fluids are direct replacements for the Dow Corning™ 704 and 705 fluids discontinued in 2011. The SPI-704 and SPI-705 have properties that are almost identical to the Dow Corning™ oils. (see specifications below). The SPI-704 and SPI-705 are man-made silicone-based fluids specifically tetamethyl tetraphenyl trisiloxane (704) and pentaphenyl trimethyl trisiloxane (705).

Durability is the biggest advantage in using silicone-based fluids. Silicone-based fluids have excellent chemical resistance, oxidation resistance and radiation resistance. These characteristics allow for longer fluid life, cleaner vacuum and better pump down times. Another advantage to using silicone-based fluids is that one can achieve a higher ultimate vacuum pressure in the range of 10-8 to 10-10 torr. Silicone-based fluids are also safer to use than hydrocarbon fluids. The threat of fire or explosion is minimized when using silicone-based fluids. Silicone-based fluids, because they are inert, do not react with metal parts, elastomeric seals, or gases such as hydrogen and carbon monoxide that are commonly found in high vacuum systems.

The single biggest disadvantage to using silicone-based fluids is their cost. They tend to be higher in cost than hydrocarbon fluids. Their price is dependent on the amount of phenyl in each type and each type will have varying amounts of phenyl. Please note that the higher the amount of phenyl, the higher the cost of the pump fluid. To achieve the maximum efficiency from your pump fluid we suggest a vigorous routine maintenance program for your pump fluids. This routine maintenance will extend the life of your pump fluid while at the same time keep your costs lower.