Recently I got a maintenance contract with a medium sized supermarket that operates mostly on medium and low temperature cases paired with small remote condensing units. In some cases the piping is quite long: 90 feet and even longer. According to the log, there had been some compressor replacements mostly related to insufficient oil return. Suction lines seem to be correctly inclined and the risers have traps. I would like to install a couple of oil separators, but I´m not very familiar with these devices. From the illustrations, I can see that the oil outlet of the separator is to be routed to the crankcase. Since most of the compressors are of the hermetic type, should I just route the oil outlet pipe back to the suction line? Additionally, I suppose that the oil pressure out of the separator must be quite high (discharge pressure maybe?) therefore, how am I suppose to reduce this pressure before the oil reaches the low side ?. I appreciate any comments.