NPT and ANPT and Garmin G5

Indiana_Pilot

Indiana_Pilot

Line Up and Wait
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Flying "B"
I somewhat understand the difference between the two (NPT and ANPT)
In the Garmin G5 manual is is wanting a 1/8-27 ANPT fitting.. I have looked for this and cannot find an ANPT fitting anywhere! I of course can find 1/8" barbed hose fittings..

Is it acceptable to use a NPT fitting with pipe thread in it's place? Or can someone tell me where one might find the fittings the G5 likes?
 
Its gotta be regular old NPT. The plugs they sent with the instrument should be a pretty good clue.
 
So can you interchange them or not? 2" is a long of material to thread...
 
I think what you'll find is that a sealant is required, not thread tape. Omitting tape on the first couple threads will prevent problems with contamination of the system by tape when the connection is made. Anytime the taped connection is broken there will be a chance of contamination. It is better to use a paste sealant properly applied. Of course "properly applied" has been a bit of a moving target over the years in some industries. Use sparingly if contamination is a concern. It doesn't take much to get a seal for quality fittings. On not so much quality fittings it might take a welder to get a seal.

By specification, NPT and ANPT are not interference threads so there is no crushing. There is wear on the thread faces every time a connection is made and broken. Lubrication helps minimize the wear.
 
That makes sense.. thanks for the info.. Is there a "plastic sealant" that is commonly used around pitot static lines? I have always seen tape..
 
I hope Brian can help recommend a sealant. I just use a lubricating paste with PTFE but I've never made up a Pitot or static line so don't know what aircraft guys use.
 
I've used tape, RTV, and others. Seems like anything but tape works fine. Screw the fitting into the hole a full turn, apply some sealant then tighten it. I've seen big blobs of clear RTV all over Cessna static ports trying to get them to seal to the cabin skin. I just drilled my static port off, cleaned everything up and reinstalled it wet with PS890B sealant. It doesn't leak.

Some of my old Cessna instruments had some green stuff on the pitot/static fittings, kinda reminded me of varnish.
 
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Anecdotally,

One of the things I sell (nothing to do with aircraft, but...) uses several 1/8-27 NPT fittings. I use yellow gas line tape rated at 10,000 psi. I've tried different tapes and putties over the years and only the 10,000 psi tape works reliably. The putty is a decent backup, but I find it messy. My products see about 2,000 psi.
 
Hercules real-tuff paste will seal the ass of an entire dysentery ward but that's just an anecdote...
 
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