I have a bunch of torches that I have picked up at garage sales. They
screw on disposable bottles. Generally they do not flare up when
inverted. But if used inverted they take a long time to shut off
after the valve is closed.

It is possible that the orfice is not snug enough in the torch and
propane is leaking around the orfice as well as through it. In that
case inverting the torch will cause a problem.

Dan



Invert the torch and you'll get some liquid propane running into the tube. If
the torch head is hot enough, it will vaporize at the orifice and the torch
will run fine. Shut the valve, though, and you've still got some liquid
propane in the tube to burn off before the flame quits.

John Martin