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Re: REFLECTOR: Teflon Tape



Jack,

Typically any pipe threads that will be exposed to pressures should be sealed
with a some type of thread sealer. You would not use a thread sealer, say,
between a flare nut fitting and the flare nut itself. Nor would you use a
thread sealer between a compression nut and its associated fitting. 

Most common in the Velocity is the 1/8" pipe fittings (about 1/4" diameter at
the threads)(most common use is the back of pitot/static instruments and
brakes), the 1/4" pipe fittings (about 3/8" diameter at the threads)(most
common use is the back of Vacuum instruments and the  hydraulic system), and
the 3/8" pipe fittings (about 1/2" diameter at the threads)(most common use is
the oil system).

Again, if these fittings are to be inserted into another metal fitting, it is
highly recommended that a thread sealer be used. I like to use liquid Teflon,
available in a tube at most automotive stores. I place a single thin bead
around the threads approximately two threads from the start. This allows for
'wiping' of the sealer onto the threads as the nut is tightened. Ideally,
enough should be used so that the is a very thin "ring" left at the end of the
nut when it is tightened. By placing it up on the threads, I also eliminate
the possibility of getting Teflon inside the fitting which too often occurs
when using Teflon tape (for some reason!).

If you are screwing these fittings into plastic, such as your flight
instruments, do not use a thread sealer. First of all, the possibility of
contamination is great and second, minimum torquing is all that is required.
Typically, anything much over finger tight on a flight instrument is too much.
If your flight instrument has a metal case, then use the smallest amount of
sealer that you can.

Hope some of this helps! Safe and Speedy construction!

Martin