Greg Smith1, Erik Boldt1, Joshua Close1, and Mark Makar1
1Solstice Advanced Materials, 20 Peabody Street, Buffalo, NY 14210, USA
Summary
To meet sustainability targets, the pMDI industry is currently negotiating a switch from high global warming potential (GWP) hydrofluoroalkane (HFA) propellants HFA-134a and HFA-227ea to low GWP propellants HFA-152a or hydrofluoroolefin (HFO)-1234ze(E). While standard flammability tests classify HFA-152a as flammable and HFO-1234ze(E) as non-flammable, and a recent manufacturing risk assessment found that HFO-1234ze(E) could be handled like non-flammable HFA-134a, there is still some uncertainty in the industry on how to handle HFO-1234ze(E) in bulk manufacturing processes when including flammable cosolvents like ethanol.
This study tested mixtures of HFO-1234ze(E) with 2.5% ethanol and 15% ethanol by the UN Globally Harmonized System (GHS) ignition distance test and an incandescing copper wire test designed to mimic an electrical equipment fault where an exposed electrical wire overheats in the presence of formulation vapours. Both studies found these mixtures to be non-flammable with results comparable to HFA-134a and ethanol mixtures in contrast to HFA-152a which was found to be flammable by both methods. This work, therefore, supports the handling of HFO-1234ze(E) like HFA-134a in pharmaceutical manufacturing environments even when ethanol is included in the formulation, subject to risk assessment to account for individual circumstances.