Use of different oil viscosities in scroll compressors

[AliCanGonc]

Hi all,

I have a r404a application where i have to use a low temperature (-35C evaporation) temperature screw compressor and medium/high temperature (0C Evaporation) scroll compressor to be used in the same circuit. these compressors are not working at the same time. I have an oil tank in the system and cannot decide which oil to use.

Screw compressor manufacturer recommends 170Cst viscosity oil, on the other hand scroll compressor manufacturer recommends 32Cst viscosity oil. The screw compressor manufacturer indicates the compressor would have major mechanical problems if lower viscosity oils are used especially in low evaporation temperature conditions.

Has anyone had experience using 170Cst viscosity oil on scroll compressors? What would be the major/minor impact?

I wouldn't mind slight performance reductions.

Thank you in advance

[seanf]

What about having two seperate systems each with its own heat exchanger, to cool a single brine system. Just swap from one fridge system to the other to cool the brine at different temps.