US EPA

4742932 

Journal Article 

Flammability and explosion characteristics of mildly flammable refrigerants 

Davis, SG; Pagliaro, JL; Debold, TF; van Wingerden, M; van Wingerden, K 

2017 

Yes 

Journal of Loss Prevention in the Process Industries
ISSN: 0950-4230 

Elsevier 

49 

Elsevier 

662-674 

10.1016/j.jlp.2017.05.019 

WOS:000412609900055 

https://linkinghub.elsevier.com/retrieve/pii/S0950423017304710
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Lab and large-scale tests were performed for mildly flammable compounds R-32, ammonia, and 1234yf, along with the flammable compound R-152a, and extremely flammable compounds methane, propane, and dimethyl ether. Properties measured at the lab scale include: the flammability limits; auto-ignition temperature; minimum ignition energy; peak constant-volume pressure rise; deflagration index; and laminar burning velocity as a function of equivalence ratio. Relationships between these properties and the probability and consequence of fire hazards are evaluated. In addition, experiments were performed in a 50 m(3) vented module to analyze the consequences of an ignition event at practical scales.



The lab-scale tests showed that the laminar burning velocity was inversely correlated with the minimum ignition energy (i.e., higher burning velocities were more easily ignited by lower ignition energies), and as expected, strongly correlated to the deflagration index. Little to no correlation was found for auto-ignition temperature amongst the fluids. In addition, the lab results showed that mildly flammable substances: (1) had a lower probability of ignition from electrical sources (e.g., electrostatic discharge, arcing, etc.), whereby the ignition energies are roughly 1-2 orders of magnitude higher than extremely flammable fluids; (2) had a lower probability of forming a flammable mixture due to higher lower explosion limit levels; and (3) resulted in significantly lower deflagration consequences. The large-scale tests confirmed that peak pressures were significantly lower for mildly flammable substances and showed that these fluids have a much lower deflagration consequence in practical applications. (C) 2017 Elsevier Ltd. All rights reserved.