Re: Needle valve -- sticking with teflon or compounding problems

["S. Hieber" <shieber at yahoo_com>]

john wheeler asked:

<> Either Tom Barr, or Wright Huntley in a recent post
> warned against using teflon tape on a needle
> valve....Or was it after a needle valve? Why?
> 
> I may have done that.

Things are probably just fine if you did, but:

The risks with Teflon tape are that it can come apart into
very fine pieces, which can then get into and clog fine
openings such as you have in metering valves, solenoid
valves, and stuff like that.


Some fitters make sure the first few male threads are not
taped so that the threads won't push the tap past  the
female threads -- the threads will hold the Teflon in
place.

The risks are greatest after you take apart a joint which
has been coated with Teflon tape.  When you do, you might
notice fine threads of Teflon in the male and female
fitings' threads.   If you do not meticulously remove these
strands, then the next time you put that joint together,
the male threads will push the Teflon pieces forward past
the female threads, ready to be blown into whatever is next
in line.

Using putty or plumber's compound instead isn't always a
solution.  The stuff sometimes dries out, becomes brittle,
and tiny pieces present the same sort of problem as Teflon
tape.

Use care when apply.  Use cleaning before refitting.  Or
try fitting your joints with out tape or compound.  Pipe
threads in relatively soft metals often seal perfectly fine
without tape or compound.

You always check your joints for leaks after fitting, don't
you?

Scott H.

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