As I have written earlier, the new refrigerant HFO-1234yf is a Category 1 Flammable Gas. This flammable gas is stored under pressure as a liquid, which by definition makes this material a candidate for a BLEVE risk assessment. For those that are not familiar with the acronym BLEVE, it stands for Boiling Liquid Expanding Vapor Explosion and this week’s “Video of the Week” is a Transport Canada training video on BLEVEs. This type of vessel failure takes the term “catastrophic failure” to new heights and in a somewhat famous BLEVE incident, an LPG railcar traveled over 3,500 feet after it BLEVE’ed.
BLEVEs are indeed an event that is considered to be a “Low Frequency – High Severity” and thus often times are overlooked as a plausible scenario. I have been sorely disappointed in some of the responses clients and I have received from so-called “reliable sources” (not so much anymore in my eyes). One such response was “this refrigerant is a mildly flammable material and carries no risks for a bleve”. Really? You can call this Category 1 Flammable Gas a “mildly flammable” all day long, as that has ZERO, zilch, NADA, zip to do with estimating BLEVE risks!!! In fact, the most recent BLEVE that resulted in three fatalities was a Carbon Dioxide (CO2) Tank in Germany and if you were not aware – CO2 is NOT a flammable gas – and in fact, it is used as an EXTINGUISHING agent around the world. So if HFO-1234yf is a BLEVE risk, what does this mean to those facilities who store HFO-1234 in ASME pressure vessels? I will cover that in a later article..