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Many people assume that a vacuum pump's performance depends only on its mechanical design. In reality, the pump oil is equally important — and in some cases, it is the limiting factor. Diffusion pump oil is heated to create a vapor jet that captures and transports gas molecules. The cleaner that vapor jet is, the lower the ultimate pressure the system can reach. This is where IOTA 705 distinguishes itself.
Let's examine what each specification means in practical terms:
Viscosity (170–175 mm²/s at 25℃): This is the sweet spot for diffusion pump operation. Too low, and the oil doesn't form a stable jet. Too high, and the pump takes too long to reach working vacuum. IOTA 705 sits right in the optimal range.
Refractive Index (1.5765–1.5785): This value confirms the oil's purity and consistency. Significant deviations from this range could indicate contamination or degradation.
Relative Density (1.090–1.10): This tells us the oil is a well-refined mineral-based fluid with predictable behavior under temperature changes.
Flash Point (≥243℃): A high flash point means the oil can be heated to the temperatures required for diffusion pump operation (typically 180–250℃) without posing a fire hazard. This is a significant safety advantage in industrial settings.
Pour Point (≤ -14 ~ -18℃): In facilities located in colder climates, this specification ensures the oil won't solidify during shutdown periods, allowing quick restarts without preheating.
Ultimate Vacuum (< 1×10⁻⁹ ~ 10⁻¹⁰ torr) and Saturated Vapor Pressure (< 3×10⁻¹⁰ torr): These two figures are the most telling. They indicate that IOTA 705 introduces very little contamination into the vacuum chamber, enabling the system to reach deep vacuum levels. For applications like electron microscopy and accelerator physics, where every fraction of a torr matters, this performance level is essential.
When a diffusion pump operates, the oil is cycled through heating and cooling repeatedly. Over time, this thermal stress can break down oil molecules, producing lighter fractions that increase vapor pressure and degrade vacuum performance. IOTA 705's high flash point and stable molecular structure resist this thermal cracking.
Oxidation is another concern. Even in well-sealed systems, trace amounts of oxygen can seep in. If the oil oxidizes easily, it will darken, thicken, and lose effectiveness. IOTA 705's antioxidant formulation slows this process, extending the oil's usable life and reducing the frequency of oil changes — a tangible cost saving for any operation.
