This part applies to the design and manufacture of refrigeration systems including piping, components, materials and auxiliary equipment directly connected to the system; specifies the requirements for testing, operation, marking and documentation of the refrigeration system. For heat transfer fluids that are not gaseous under atmospheric pressure, the requirements for the heat transfer fluid circuit do not belong to the scope of this part, but this part still applies to any safety devices related to the refrigeration system. This part does not apply to refrigeration systems using air or water as refrigerants, nor does it include requirements for refrigeration equipment used in potentially explosive atmospheres.