Knowing the largest mass of refrigerant and the smallest enclosed space, the designer can determine system compliance with B52 code. Next, the total mass of the largest refrigerant circuit is calculated because when a leak occurs there is potential for the entire contents of the circuit to vapourize into one space. It may be a single room or an entire floor, depending on whether the refrigerant circuit physically passes through a space or if it passes through duct work supplying air to many spaces. This involves identifying the smallest enclosed space where refrigerant containing parts are located. When designing a refrigeration system, the designer must determine the worst case scenario in the event of a refrigerant leak. Whereas others are limited by the lower flammability level or may be immediately dangerous to life and health. Some are limited by cardiac sensation level where inhalation can cause heart irregularities. As some refrigerants are tasteless and odourless, their vapours can create an oxygen deprived environment without any signs to the occupants. Mass may be limited to maintain a minimum oxygen concentration level of 19.5%.

Depending on the refrigerant, the permitted mass per volume of space varies.

The Canadian Standards Association published B52 Mechanical refrigeration code, which limits the mass of refrigerant deemed safe in a volume of occupied space. As refrigerants have low boiling points, leaked refrigerant changes to a vapour state and can accumulate to create a potentially dangerous environment. Many different compounds are used as refrigerants, but unfortunately many compounds that make excellent refrigerants can be harmful if leaked into an occupied space. A refrigerant is cycled through this circuit absorbing heat in one space and rejecting it to another. A refrigeration system is a combination of equipment connected in a closed circuit.

B52 mechanical refrigeration code