Diffusion Pump Oil Coking: A Common Problem Affecting Vacuum System Stability

In processes such as vacuum coating, vacuum sintering, and electron tube manufacturing, diffusion pumps require continuous high-temperature heating to maintain the vacuum environment. Under prolonged high-temperature operating conditions, if the pump oil lacks sufficient thermal stability, it is prone to oxidative decomposition, producing coking and carbon deposits that adhere to the inner walls of the pump chamber and the nozzles. This not only reduces pumping efficiency and causes a drop in vacuum level, but also increases the frequency and cost of equipment cleaning and maintenance, and may even disrupt production continuity. Therefore, selecting a diffusion pump oil with strong thermal stability and good oxidation resistance is key to reducing coking and extending oil change intervals.

IOTA 704: Balancing Thermal Stability and Oxidation Resistance

IOTA 704 is a pump oil specifically designed for high-vacuum diffusion pumps. Its molecular structure has been optimized to deliver excellent stability under high-temperature environments.

• Excellent Thermal Stability: Under the continuous heating operating temperatures of diffusion pumps, IOTA 704 is resistant to thermal decomposition and maintains stable physical and chemical properties over the long term, reducing the formation of coking and carbon deposits.
• Excellent Oxidation Resistance: Even when exposed to trace amounts of oxygen at high temperatures, IOTA 704 effectively resists oxidation, preventing oil degradation and vacuum level drops caused by oxidation.
• Low Saturated Vapor Pressure: With a saturated vapor pressure below 2×10⁻⁸ Pa, it ensures that while reducing coking, it can still help diffusion pumps achieve an ultimate vacuum of 10⁻⁷ to 10⁻⁸ Pa.
• Reliable Physical Parameters: Viscosity at 25°C is 38±3 cSt, open-cup flash point ≥210°C, and pour point -35°C, making it adaptable to a variety of operating conditions.

Application Scenarios

IOTA 704 is suitable for industries and equipment with high requirements for oil stability:

• Vacuum Coating Industry: Reduces film layer contamination caused by oil decomposition and improves coating quality.
• Vacuum Metallurgy & Sintering: Enables extended operation in high-temperature furnaces while reducing cleaning frequency.
• Electronic Device Manufacturing: Used in the evacuation and encapsulation of electron tubes, light bulbs, displays, and other devices, maintaining a clean vacuum environment.
• Scientific Research Instruments: Suitable for equipment such as electron microscopes, mass spectrometers, and atomic energy accelerators, ensuring experimental stability.

Technical Specifications

表格

Parameter	Value
Appearance	Colorless or transparent liquid
Viscosity (25°C)	38±3 cSt
Relative Density (25°C)	1.06~1.07
Refractive Index (25°C)	1.5500~1.5600
Flash Point (Open Cup)	≥210°C
Pour Point	-35°C
Ultimate Vacuum	<10⁻⁷~10⁻⁸ Pa
Saturated Vapor Pressure (25°C)	<2×10⁻⁸ Pa

About IOTA

As a full-chain silicone solutions provider, Anhui IOTA Silicone Oil Co., Ltd. offers customers technical services ranging from product selection to application support. IOTA 704 is one of the products we have launched for high-vacuum diffusion pump applications. If you are looking to reduce diffusion pump coking issues and extend oil change intervals, IOTA 704 is worth considering for your selection. For Technical Data Sheets (TDS), Safety Data Sheets (SDS), or technical consultation, please visit our website or contact our technical team.

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FAQ

Why does diffusion pump oil coke easily?
The main reason is insufficient thermal stability of the pump oil at high temperatures, leading to oxidative decomposition and the formation of carbon deposits and coke-like substances. Can IOTA 704 reduce coking?
Yes. IOTA 704 has excellent thermal stability and oxidation resistance, making it resistant to decomposition under high-temperature operating conditions, which helps reduce coking and carbon deposits. What is the ultimate vacuum of IOTA 704?
It can help diffusion pumps achieve an ultimate vacuum of 10⁻⁷ to 10⁻⁸ Pa, with a saturated vapor pressure below 2×10⁻⁸ Pa. Which industries is IOTA 704 suitable for?
It is suitable for vacuum coating, vacuum smelting, electron tube manufacturing, light bulb production, display manufacturing, electron microscopes, atomic energy accelerators, and other fields. What is the viscosity of IOTA 704?
At 25°C, its kinematic viscosity is 38±3 cSt. What are the flash point and pour point of IOTA 704?
Open-cup flash point ≥210°C, pour point -35°C. What packaging sizes are available for IOTA 704?
Available in 1 kg plastic bottles, as well as 5 kg, 25 kg, 50 kg plastic drums, and 200 kg iron drums. Is IOTA 704 a hazardous material?
It is transported and stored as a non-hazardous material. Storage conditions: moisture-proof, humidity-proof, away from direct sunlight, with a temperature range of -40°C to 50°C. What is the shelf life of IOTA 704?
Under the specified storage conditions, the shelf life is 3 years. How can I obtain technical documentation for IOTA 704?
Visit the Anhui IOTA Silicone Oil Co., Ltd. website or contact our technical team to obtain the TDS and SDS.
Silicone Diffusion Pump Oil IOTA 704 （Replacement for DC704）-IOTA