Teflon Tape

["Sherlock Wong" <s_wong at aristoslogic.com>]

A plumber at Home Depot told me that teflon tapes does not seal the
joint. When a coupling is tightened, it generates heat, which makes it
harder
to tighten fully. The teflon provides lubrication, allowing the coupling
to be
tightened fully.

Normally, with plumbing, overtightening is bad. But I think that CO2 is
different,
by tightening the coupling, you are compressing the washer into the
groove on
the tank valve. To compress the washer takes alot of force on the
wrench.
The beer supply place where I get my CO2 refilled said to put all my
weight
on the wrench to tighten the nut.