Discussion on the use of supercoolants as alternatives to lubricating oil in Ingersoll Rand oil-free screw compressors
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Our company owns several single-stage and multi-stage Ingersoll Rand oil-free screw compressors, with the following specifications:**Single-stage oil-free screw compressor**
Medium: Air
Inlet pressure: Atmospheric pressure
Outlet pressure: 3 kgf/cm²
Discharge temperature: 250 degrees Celsius
Air volume: 3,500 cubic feet per hour
**Multi-stage oil-free screw compressor**
Medium: Air
Inlet pressure: Atmospheric pressure
Discharge temperature of first stage: 185 degrees Celsius
Discharge pressure of first stage: 1.9 kgf/cm²
Discharge temperature of second stage: 200 degrees Celsius
Discharge pressure of second stage: 7 kgf/cm²
**Request for assistance:** Since the original Ingersoll Rand SSR Ultra Coolant is too expensive, we have switched to domestic lubricants for use in these compressors. The options available include Shell Dexos 46#, Mobil Thermax 46#, and Great Wall Lubricants 4502 46#. I would like to know if anyone else has experience with such alternatives. I’ve seen that domestic lubricants are generally used in oil-based screw compressors, where it is required that the compressor’s discharge temperature not exceed 110 degrees Celsius. In those cases, the lubricant comes into contact with the compressed gas. However, in oil-free screw compressors, the lubricant does not enter the compression chamber. Does this mean that the lubricant’s flash point still needs to be at least 40 degrees higher than the compressor’s discharge temperature? Given that my compressor’s discharge temperature is 250 degrees Celsius, the lubricant’s flash point would need to be above 280 degrees Celsius. Yet all three of the lubricants mentioned above are synthetic hydrocarbon-based oils, with flash points ranging from 230 to 250 degrees Celsius. Can such lubricants be used? I would appreciate it if any experts among you who have experience with various types of compressor oils could share their knowledge. Thank you!
I recommend Mobil Racer 46#. Personally, I think Mobil’s lubricants are of very good quality. We use Gardner MV46 hydraulic oil here, and it works well too.
It is recommended to have the lubricant manufacturer conduct a comprehensive assessment
The lubricant for oil-free screws does not come into contact with the medium, and the oil temperature generally cannot exceed 100 degrees. It is usually below 80 degrees.
Yes, the normal oil temperature is around 65 degrees
I asked several manufacturers of major lubricants, and they all said it could be used, but there were no case studies to support this, so I wasn’t confident enough to use it. According to Ingersoll Rand’s instructions, a PAO synthetic oil with a viscosity of 46 is recommended; lubricant manufacturers say that as long as the viscosity is 46, synthetic oils with similar compositions can be used.
The flash point of Mobil Racer is only 200 degrees, while that of Super Coolant is 271 degrees; it’s this difference in flash points that’s an issue. Do you have experience replacing oil in air compressors?
Oh, that’s a bit of a dilemma. I want to save some money, but I don’t have enough case studies to back it up, so I dare not use it. Sigh. . . . . I understand your difficulties. . .
Just find the right air compressor oil. The maximum temperature for such oil is around 120 degrees; it has an automatic regulation system to prevent temperatures from rising too high. Moreover, the air compressor oil does not come into contact with the compressed medium