The oil separators should be installed in the discharge line between the compressor and the condenser mounted securely in a vertical position and reasonably close to the compressor. To prevent the return of refrigerant from condenser, during the off cycle of the system, it's advisable to install a check valve between the condenser and oil separator outlet connection.
Oil separator performs best when operating at or near the compressor discharge temparature. In location the oil separator,choose a position to avoid, as far as possible, chilling of the shell, which may result in condensing of liquid within the separator. If this is not possible, it is advisable to supply the saparator with the better solutions (insulation, strap heater, others) to prevent the refrigerant in the system from condensing in the shell. Before the oil separator is installed, an initial charge of oil should be added to it. Refer to general characteristics of oil should be added to it. Refer to general characteristics of oil separators or to instruction sheet for the proper amount of oil. Oil pre-charge is very important, failure to pre-charge separator sump may result in damage to the oil return float mechanism. Use the same type of oil that is in the compressor crankcase.

Acting as the layout of refrigerating system, the return line may be running from the oil fitting to:

Castle oil separators are manufactured from deep drawn special steel of adequate thickness.
End connections are manufactured from special steel bars.
The internal float ball is constructed of Stainless Steel.