Propane regulator question

I'm working with our local propane (and propane accessories guy to get a
100# propane tank for the studio. He has some regulators on hand and has
asked specifically what sort of PSI lampworking uses for the propane end of
the mix. Can someone help me with that? In the books or sites I've seen,
they talk about one-stage and two-stage regulators but they never mention
the PSI needs. He has the two-stage regulators, I believe.

Also, he thought that a flashback arrester was just sort of a gimmick. He
had actually never heard of the term and is going home at lunch to look at
the site where I first saw them to find out what they are. What's
everyone's opinion on this bit of info? Does he not know what he's talking
about, is the terminology just odd or are they a gimmick?

Thx,
Giselle