As the policy-driven refrigerant transition takes hold in the HVAC industry, mechanical engineers are encountering a new challenge to ventilation system design. Refrigerants widely used in central chiller plant systems that will be prohibited in new equipment, though high in their measure of global warming potential (GWP), are classified by ASHRAE as having “no flame propagation” (or in the common vernacular, “not flammable”). Low-GWP refrigerants entering the market to replace them include a new collection of refrigerants classified as having low flammability. As a result, chiller plant ventilation design guidelines have undergone rapid change in pursuit of chiller plant safety.
Through the past two decades, after the phase-out of earlier common refrigerants such as R-22 had begun in service of environmental stewardship, refrigerants R-134a and R-410A have dominated usage in central chiller plants containing centrifugal and positive displacement chillers. These plants include refrigerant leak detection and ventilation systems governed by ASHRAE Standard 15 Safety Standards for Refrigeration Systems and its companion, ASHRAE Standard 34 Designation and Classification of Refrigerants.