A Method for Determining Practical Flammability Risk When Using Refrigerant Blends

Abstract

This paper proposes a method for establishing improved guidelines regarding the use of refrigerant blends that contain a flammable component. This approach was verified in a test chamber under realistic refrigerating equipment leak scenarios. First, the paper provides an overview of the safety classification described in ANSI/ASHRAE Standard 34-2007, Designation and Safety Classification of Refrigerants (ASHRAE 2007) and its international equivalent ISO Standard 817-2006, Refrigerants—Designation and Safety Classification (ISO 2006). The refrigerant blends examined were A1, as formulated, and A2, at the “worst-case fractionated formulation,” as defined by ASHRAE Standard 34-2007. The blend is prepared in a cylinder and is then slowly leaked inside a test chamber of 1 m³ (35.31 ft³). At the beginning of the leak, the gas phase occupies 10% of the cylinder volume, corresponding to one of the leak scenarios featured in ISO Standard 817-2006. The concentrations inside the test chamber are measured by gas chromatography. In addition, this paper provides the algorithm of calculation of a computer code named Room_leak, which simulates leaks of any refrigerant blends in realistic scenarios.