1. piping arrangement on an enclosed compressor to equalize refrigerant gas pressures in crankcase and suction; also a device for dividing the liquid refrigerant between parallel low-side coils; also a piping arrangement to divide the lubricating oil between the crankcases of compressor operating in parallel or in tandem.

2. piping arrangement to maintain a common liquid level or pressure between two or more chambers.

3. piping arrangement to equalize steam header pressure and condensate return pressure in a steam boiler.