Refrigerant HFO-1234yf is a Flammable “4” in the NFPA 704 Diamond (Part 2)

In Part 1 of this series I established how this material is a Category 1 Flammable Gas based on both the manufacturer’s SDS and OSHA’s Hazardous Communications Standard Appendix B.  In this article I wish to address how an HFO-1234yf storage tank, which is an ASME pressure vessel, should be labeled, versus how some have been found labeled.  This article will apply to BOTH NFPA 704 “Diamonds” and the Hazardous Materials Identification System (HMIS).  I have observed incorrectly labeled HFO-1234yf pressure vessels more times than I have seen correctly labeled vessels.  I am trying to figure out how this error came about, but my gut tells me we have once again placed too much emphasis on “marketing materials” rather than SDS data and in two cases, the manufacturer actually instructed the business to use the HMIS Flammable “2”.  Without question, HFO-1234yf is a Flammable “4” in both the NFPA 704 and the HMIS labels and here’s why…