Hooooo-Weeeeeeeeeee!!
Flashbacks are a pretty dangerous thing. Look what "
could" have happened if it would have reached your propane tank. (
CLICK HERE).
A flashback is caused by the reverse flow of gases upstream into the hoses or other equipment. This reverse flow is usually the result of:
1) improper shutdown and/or startup procedures;
2) allowing cylinder pressures to become too low; or
3) a check valve that is not working properly.
You never mentioned if you had a "check valve" or a "flashback arrestor".
If you DON'T have a flashback arrestor...get one. (And double check the latter three reasons for this phenomenon).
FYI, oxygen in itself is NOT flammable. It AIDS in the combustion of flammable/combustable materials and gasses. I may be wrong - like my wifey-poo usually tells me I am - but it sounds like you had a backfire (the initial "pop" you heard) which tells me you had a small internal flame. And coupled with the oxygen in your hose, and not enough fuel pressure, may have caused your problem.
Always check your fuel pressure when initially starting, and then recheck it after you have everything set at your working pressures. And always bleed your fuel hose after you are done.
Oh yea...and try to follow P.O.O.P..
Lesson learned - the hard way.
In Christ: Raymond