The flammability of R-245ca
R-245ca (1,1,2,2,3-pentafluoropropane) has positive thermophysical properties and a zero ozone depleting potential, making it a candidate to replace some CFC refrigerants. Past measurements using the ASTM E681--85 method suggest that R-245ca is nonflammable at room temperature using dry air, but that increasing the humidity allows for a flame to be momentarily sustained for a narrow range of R-245ca/air mixtures. An alternative means for measuring flammability, using a premixed, counterflow burner, was developed specifically for alternative refrigerants, and has been demonstrated to yield accurate and consistent flammability limits for R-32 and R-125/R-32 mixtures at room temperature and 100 C. The same apparatus has been modified to handle the higher boiling point of R-245ca. No steady flames of pure R-245ca in air could be stabilized at the lowest flows attainable in the apparatus; however, when mixed with R-32, flames could be maintained at R-245ca/R-32 ratios up to 62/38. By conducting a series of extinction tests with changing flow rates and mole fractions, the results may be extrapolated to conditions of zero flow (most flammable) and no R-32 to determine if R-245ca and air mixtures are flammable. The results show that R-245ca is flammable at an ambient temperature of 100 C and 50% relative humidity corrected to 23 C. When air humidity was kept at 50%, but the initial temperature was reduced to 50 C, R-245ca was found to be nonflammable. R-245ca in dry air (0% humidity) at 100 C was also determined to be nonflammable. The measurements confirm the sensitivity of the flammability of R-245ca to initial temperature and humidity.
- Research Organization:
- Building and Fire Research Lab., Gaithersburg, MD (US)
- Sponsoring Organization:
- Air-Conditioning and Refrigeration Technology Institute
- OSTI ID:
- 20085704
- Country of Publication:
- United States
- Language:
- English
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