The Importance of Fluid Selection in Vacuum Technology

Selecting the right diffusion pump fluid is one of the most important decisions in vacuum system operation. The fluid influences ultimate vacuum level, pumping stability, maintenance frequency, and overall process cleanliness. A poorly chosen fluid can limit vacuum performance, increase contamination risk, or require more frequent intervention. Silicone Diffusion Pump Oil IOTA 705 is designed to address these concerns by offering a single-component fluid with strong ultrahigh vacuum characteristics and reliable physical properties.

Formulated for Deep Vacuum Performance

IOTA 705 is a colorless, transparent oily fluid intended for ultrahigh vacuum applications in the range of 5×10⁻⁹ to 10⁻¹⁰ torr (untrapped). Its ultimate vacuum performance is listed as 1×10⁻⁹ to 10⁻¹⁰ torr (untrapped), making it suitable for systems where deep vacuum is required. The extrapolated vapor pressure at 25°C is 3×10⁻¹⁰ torr, a specification that underscores its suitability for sensitive vacuum environments. The fluid’s chemical composition is based on pentaphenyl trimethyl trisiloxane, with CAS No. 3390-61-2. Its alternative names include 1,1,3,5,5-pentaphenyl-1,3,5-trimethylsiloxane, 705 super high vacuum diffusion pump oil, 705 diffusion pump fluid, phenylmethylsiloxane oligomers, and oil for diffusion pump.

Physical and Thermal Characteristics

The physical properties of IOTA 705 reflect its design for stable operation. It has a specific gravity of 1.090–1.100, a viscosity of 170–175 cSt at 25°C, and a viscosity of 61–64 cSt at 40°C. These values help define its flow behavior and operational consistency. The flash point of ≥243°C provides a strong safety margin for high-temperature vacuum applications. The congealing point of ≤-14 to -18°C ensures that the fluid remains suitable for use in cooler environments. The refractive index at 25°C is 1.5765–1.5785, and the molecular description is 546.

Silicone Diffusion Pump Oil IOTA 705 （Replacement for DC705）-IOTA