Hi, I posed some questions regarding the use of hydraulics before in this forum, and this time I would like to know if it is technically possible to use refrigerants or steam to drive a hydraulic cylinder. It's part of an organic rankine energy generation project I'm hoping to attempt. I have been previously offered suggestions to use air cylinders, air motors, centrifugal pumps, turbo expanders etc for such a purpose. However, I am only specifically interested just to know whether it is possible to use hydraulic cylinders driven by refrigerants or steam. Part of the reason is hydraulic cylinders are able to handle much more pressure than air cylinders, which can handle maximum of 150 psi. The pressure I am looking at could be as high as 300 psi or more. So instead of having to custom make an air cylinder to handle those pressure, why not simply use a hydraulic cylinder which can handle the pressures easily? Would there be problems of friction, leakage or corrosion? So far I have found no evidence that says that this cannot be done. Hence, I am looking for some opinion here as to whether it is doable. If it is indeed possible, I would also like to know what kind of lubricants (if needed at all) is suitable for this type of usage as well as how much and how often to apply. Any tips on this would be appreciated. Thx in advance.