Source of green donuts for instrument tubing installation?

On Monday, 9 April 2018 10:05:36 UTC+3, wrote:
Using them prevents leaks later on, clamping the tubes.

I have fixed two leaks in pitot static systems over the years. Both were caused by clamped fitting. That's when I started to take seriously the instruction to never clamp pneumatic tubes with anything. Silicon tubes are idiot-proof, PVC tubes age and may become loose if fitting is connected frequently, the fix is to shorten the tube few centimeters and then plug it back.

On Friday, April 6, 2018 at 10:49:23 AM UTC-7, Movses Babayan wrote:
None of the usual suspects online produce results - or I don't search using correct terms.

Movses, I have a bunch because I had to buy 100 of them. I only needed a dozen. I'll bring them to BoD this Tuesday.

-Kevin

On Monday, April 9, 2018 at 3:05:36 AM UTC-4, wrote:
Using them prevents leaks later on, clamping the tubes.

Has anyone ever tried a short piece of shrink-sleeve - no longer than the barbed fitting on the instrument - over the tubing? Slip it into place and hit it with a hot-air gun. Should shrink uniformly before doing damage to the tubing.
Uli
'AS'

"Has anyone ever tried a short piece of shrink-sleeve - "

Probably not a good idea. It will help the sealing, but the contraction when heated does not impart a lot of actual compressive force. Also, you will need a razor knife to get it off, which will likely damage the tubing.

I like these:

https://www.amazon.com/Wingsmoto-Tub.../dp/B012MBHEHQ

8.5 mm may not be exactly the size you need.

krasw wrote on 4/9/2018 12:39 AM:
On Monday, 9 April 2018 10:05:36 UTC+3, wrote:
Using them prevents leaks later on, clamping the tubes.

I have fixed two leaks in pitot static systems over the years. Both were caused by clamped fitting. That's when I started to take seriously the instruction to never clamp pneumatic tubes with anything. Silicon tubes are idiot-proof, PVC tubes age and may become loose if fitting is connected frequently, the fix is to shorten the tube few centimeters and then plug it back.

Yep, use silicone tubing. It doesn't age like the clear plastic stuff, and remains
easy to push on and pull off. My glider came with the plastic lines for the pitot,
static and TE, so I shortened them, then added back the length needed with a
barbed plastic fitting and silicone tubing. No more tubing problems, and easy to use.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf