What issues could arise from using hydrogen for explosion testing instead of propane?

Explosion testing with hydrogen should be utilized only where there is not an established alternative and then only by personnel experienced in such testing. 
Testing with hydrogen is always a challenge and needs to be approached carefully due to significant differences in properties between hydrogen and propane. Hydrogen can develop significantly higher overpressures and preliminary testing with leaner mixtures and possibly smaller containers should precede full-scale application tests. Documents such as NFPA 2, NFPA 68, and NFPA 60 provide additional guidance on the potential explosion hazards and properties of hydrogen.