Jim..i had the safety valve on a very old Primus 71 blow and it did not make much more than a candle type flame that i was able to blow out..it relit of course so i just let it go until the pressure was normal.i would think if the cap is in good shape with the proper setting built into it you should not get a flamethrower...but it was a once only thing for me so i can't say how another stove might act.