Hello Samak,

It CAN be done, but I am not sure about the consequences for the life time of the elements and or maximum pressure/capacity change of the compressor.

A little secret: I know that the same compressor element is often used on different compressors. They make the element run at an higher RPM to create more flow (increase capacity), but limit maximum pressure.

Then, on another model, with the same compressor element, they run it at lower rpm, with reduced capacity but higher maximum pressure.

I even know, that on some (portable) compressors, the only difference between one model and the more expensive model (higher capacity) is a change in the RPM of the motor.

But, these are all oil-injected screw compressors. I am not sure about oil-free screw compressors.

That being said, I don't know what the consequences are for your compressor.

Safest would be to make the elements run at the same speed with the new motor. But this would involve changing the gear ratio of the gears. Finding and installing the right gears is probably more expensive than a new electro motor!

Since this is an oil-free screw compressor with two elements (low pressure and high pressure), I would not recommend to make it run at an higher rpm.

The compression efficiency of both elements will change, resulting in a new 'balance' between the two elements (at load/unload) and a different intercooler pressure, pressure ratio's and temperatures..

On a single element oil-injected compressor, my answer would be 'it's probably ok'. On an oil-free compressor, my answer would be 'No'.

Hope this was of any help! Good luck! let me know if you need more info!

Cas