Hello. I just discovered this site and am hoping someone can steer me in the right direction. Let me start off saying that I am a plant engineer, not a refrigeration engineer. I know enough about refrigeration to annoy the chiller repairmen, but that is about all.

My plant has two chillers supplied by a now out of business company named McCormack Manufacturing. The chillers are about 16 years old, are rated at 12 tons capacity, and are water cooled. The chillers have screw compressor/oil separator units made by Mayekawa. The compressor is a model 125LUD-HX-SU. The chillers are charged with R-22 refrigerant. The coolant used is D-Limonene and we are controlling the leaving water temperature at -28 F. Suction pressure is in the 0-3 psi range and the discharge pressure is in the 190-210 psi range.

We have to either retrofit the chillers with another refrigerant or replace them with new machines using a different refrigerant. It has been suggested that R-507 might be the best alternative refrigerant to use in this application.

My questions are:

1. Is R-507 the best refrigerant to use for replacing the R-22 in this type of application?

2. What are the negatives for retrofitting the existing chillers with R-507 (or a different one if it is a better choice)? Would I have to change major components like a compressors, compressor motor, evaporator, or condenser?

3. The Dupont information for Suva R-507, says that R-507 gives a slight increase in capacity at the temperatures we maintain. Is that true or just advertising hype?

4. What kind of operating temperatures and pressures should I expect?

Thanks for your time.

3. How much