Hi Richard
"I am fitting the factory water drains to to my tank and wanted to know
what is best to seal the threads where the joints screw together? My first
thoughts are PTFE Thread tape, or a smear of Redux. Or is there something
El's?"
As mentioned teflon tape is not a good idea. Besides chance of sending a
sliver somewhere especially if you ever remove and reinstall, it can
easily allow over tightening and break something, and perhaps not right
away!
Better off with no teflon tape dry than with.
That said, I began using just a little on threads, missing the first
thread all together of EZ Turn (Fuel Lube) purchased from Aircraft Spruce.
BTW I disassembled and very careful inspected supplied fuel selector, it
was OK and used EZ Turn to lubricate. There is more than one Cessna 150
that uses same valve that had instructor turn off fuel on student and have
it break closed. They can get very tight, best to keep lubed well. If you
find someone you don't like, put a smear of this wicked thick and
imposable to remove compound on their car windshield!
Then for majority of fuel system am using PTFE based thread compound,
again just a little and missing the first thread all together. This will
allow easy removal and install. After listening what Flowscan had to say
and my experience PTFE it is for me.
There are some instances, like on fuel tank output nipple with copper
extension for mono water drain, I used Redux. If fit was not the greatest
I have added just a little flox to Redux. You can probably remove (heating
would help I am sure) but would limit to things you are pretty certain you
will never touch. that is not the case for water drains that will need new
O-Rings / and or complete replacement after a while.
Flowscan 201Bs on some Certified Aircraft installs recommend dry install
of pipe threads. Flowscan themselves (and some certified installs)
recommends PTFE based thread compound. They are very specific as to which
type of compound, think it is a Loctite product which is what I am using.
If you need let me know and I will look up part number.
Note DO NOT INSTALL ALUMINIUM FITTINGS on a Flowsacn 201B transducer. I
hand screwed in by finger dry a 45 degree fitting to choose one with
thread that would allow proper orientation, and it galled and took out
half the threads on way out. I was able to hand grind a bottoming tap even
further, and got back half of normal threads and Redux/floxed it in place.
Whew.
I suppose if you have an aluminium body something or other (gasculator or
fuel selector) you could probably get away with using an aluminium fitting
if you used EZ Turn or PTFE based thread compound (or Redux), but I would
not. Better off using Brass, Stainless or Steel fitting to ward off
galling. You can not believe how a hand tightening could weld together
aluminium so well.
Having a Mono, I installed copper tube to reach aft section of tank. I
used this as an advantage and made my gauze filter close to two times the
length of factory recommended length. Instead of using factory supplied
screen that is very course, I went to about half as fine and used some
stainless steel mesh from McMaster Carr. Without the copper tube it would
be too long to support itself I fear. Thus turned an aluminium spacer that
was Reduxed to the copper tube as a support for end of screen! I also did
a two time wrap of safety wire at end over aluminium again Reduxed, and a
token 2 time wrap in center. Wayne can't find some early build pics, this
included. I did a quick test and am pretty confident that I can borrow
some dog hair from PTAG, and not have it pass screen and clog nipple
inlet, yet course enough to let through what I want.
I have a picture posted at:
http://www.europaowners.org/modules.php?set_albumName=Begin-06-2003&op=modload&name=gallery&file=index&include=view_album.php
Under:
914 modular fuel system. Series with bypass, two Andair 375s.
Of my water drain location. I made these with 1/8" NPT for inlet (and
sight gauge) and 1/4NPT for drain. Sight gauge will be for ground checking
only (nipple has restrictor in it). Have Factory float style reed switch
gauge for inflight.
Ron Parigoris
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