Developing a Standard Covering Design Considerations of Using Flammable Refrigerants for Cooling ISO Marine Thermal Containers

摘要

Due to GWP limitations on refrigerant gases used in some countries there is pressure to findalternatives to the third-generation HFCs for refrigerated marine containers built to ISO 1496. Many ofthe alternatives refrigerants are classified by ASHRAE as flammable therefore an ISO standard wasdeveloped to try to ensure their safe operation whilst using those fluids.Flammable refrigerants vary in burning velocity, heat of combustion and toxicology which determinetheir classification under ISO 817. As HFC-134a and HFC-404A are non-flammable and low toxicitythere are few requirements to consider whether a leak or system malfunction could lead to a potentiallydangerous atmosphere occurring.For flammable refrigerants, there is a risk of ignition or decomposition in the event of leakage by eitherthe refrigeration system itself or an external ignition source or hot surface.This paper examines the requirements for design as defined in ISO 20854 for safe operation, why theyare included and how they were arrived at.