I don't know if it will help but I remember having a talk with one of the tech reps from a petroleum company some years ago and him saying that to have an "Explosion" you need the correct temperature and vapour concentration. We were talking about explosions at petrol stations and he said the temp needed to be min 20c and the vapour concentration 200ppm (Parts Per Million). When we sat down and worked it out it meant a warm day and a lot of spilt fuel.

Your biggest concern needs to be ambient temp. If you can get it over 20c then I think you have a better chance of getting the result you want.