There is currently an ignorance of the complexity of safely firing 70 year old military flamethrowers. There are several reasons military flame throwers were not fired prior to 1993. First the knowledge how to service them was missing and they simply could not be made to work. Secondly the equipment to hydro test was missing and a large percentage of flame thrower tanks would explode when pressurized. And lastly the fuels, pressures and lack of training were inherently very dangerous.
I have recently witnessed someone operating a WWII M2-2 flamethrower that was just barely made operational but not all the systems like the pressure relief valve had been service or tested. This is very dangerous and will eventually lead to injuries, fatalities and government regulation of all flamethrowers.
Safe Firing Requires Three Things:
1. Mil-Spec service of flamethrower including rebuild and testing of all systems with hydro test of fuel tanks and final test firing. See Restorations.
2. Operator training in a controlled environment by an experienced instructor who completely understands flame throwers and safety training. See Operator Training.
3. Strict adherence to safety rules which includes not volatile fuels, nitrogen propellant, lower pressures and a well controlled range. See Safety Rules.
These Guidelines were developed by the military for over 100 years, and using them I have fired thousands of times without any injuries or failures. But these guidelines must be followed.