Instrument tubing

[soaringjac]

Where does one get those "doughnuts" that you put over instrument tubing to help secure and seal the connection?

[Dan Marotta]

I've used safety wire for that purpose, being careful not to make it too
tight.

On 8/7/2019 9:12 AM, soaringjac wrote:
> Where does one get those "doughnuts" that you put over instrument tubing to help secure and seal the connection?

--
Dan, 5J

[Peter F[_2_]]

Vet
Agricultural supplier
ebay

They're intended to do nasty things to sheep

At 15:12 07 August 2019, soaringjac wrote:
>Where does one get those "doughnuts" that you put over instrument tubing
to
>help secure and seal the connection?
>

[Richard Pfiffner[_2_]]

On Wednesday, August 7, 2019 at 8:12:19 AM UTC-7, soaringjac wrote:
> Where does one get those "doughnuts" that you put over instrument tubing to help secure and seal the connection?

Don't waste your time using those they are not needed.

Richard

[Tango Whisky]

Exactly. Tubing should be silicone. No additional devices needed.

[soaringjac]

On Wednesday, August 7, 2019 at 9:27:34 AM UTC-7, Tango Whisky wrote:
> Exactly. Tubing should be silicone. No additional devices needed.

I plan on using the colored tubing from Wings and Wheels. Good stuff?

[[email protected]]

Absolutely, very good tubing!

[Richard Pfiffner[_2_]]

On Wednesday, August 7, 2019 at 12:46:40 PM UTC-7, soaringjac wrote:
> On Wednesday, August 7, 2019 at 9:27:34 AM UTC-7, Tango Whisky wrote:
> > Exactly. Tubing should be silicone. No additional devices needed.
>
> I plan on using the colored tubing from Wings and Wheels. Good stuff?

Craggy Aero also has tubing

http://www.craggyaero.com/tubing_&_fittings.htm

Richard
www.craggyaero.com

[Charlie Quebec]

I use silicon tube of 5mm ID cut into 10mm pices and stretched over the tube and fitting.
The rubber donuts deteriorate very quickly to the point of being useless.

[Charlie Quebec]

The rubber rings are called docking rings.

[Surge]

On Wednesday, 7 August 2019 18:27:34 UTC+2, Tango Whisky wrote:
> Exactly. Tubing should be silicone. No additional devices needed.

I can't agree more. Silicone tubing will practically last the rest of your lifetime, it never leaks and it reseals when removed and reconnected.

I used "food grade", thick walled, silicone tubing sourced from China due to the low price (around $50 for 12 meters) and free shipping. Red for pitot, blue for static, black for T/E.

PVC tubing is for fish tanks.

[[email protected]]

On Thursday, August 8, 2019 at 10:34:23 AM UTC+1, Surge wrote:
> On Wednesday, 7 August 2019 18:27:34 UTC+2, Tango Whisky wrote:
> > Exactly. Tubing should be silicone. No additional devices needed.
>
> I can't agree more. Silicone tubing will practically last the rest of your lifetime, it never leaks and it reseals when removed and reconnected.
>
> I used "food grade", thick walled, silicone tubing sourced from China due to the low price (around $50 for 12 meters) and free shipping. Red for pitot, blue for static, black for T/E.
>
> PVC tubing is for fish tanks.

Behind the panel soft silicone tubing needs a lot more care on installation to ensure that it is fully supported otherwise it moves around in turbulence and when pulling G and that can cause pressure change to the vario. PVC tubing also needs care in that respect but less so. I never use silicone tubing or donuts or tie wire and have never had a leak at the instrument. I take care to make sure that T pieces etc are free of flashing - metal ones are better. The only downside of good PVC tubing is that a 90 degree bend that looks OK on installation can go flat over the years and cause a blockage so I always use 90 degree corner joining pieces instead.

[John DeRosa OHM Ω http://aviation.derosaweb.net]

Couple of things;

- I used to be a proponent of the small castration rings but feel they actually cause leaks instead of preventing them. YMMV. Plus they fairly quickly deteriorate by design.

- I like the "Wings and Wheels" tubing color coding scheme. Helps to prevents errors and makes seeing which tube goes to what much easier.

- All this info and more is in this presentation.
http://aviation.derosaweb.net/presentations/#airlines

Enjoy!

[Wit Wisniewski]

I use spring steel hose clamps like these:
https://www.dhgate.com/product/motorcycle-5mm-6mm-7mm-8mm-9mm-spring-clip/404217759.html
They come in many sizes, and each size will work with a variety of tubing sizes. They're cheap, and reusable. A downside is that pliers are required to install and remove them.
For tubing short runs, I haven't found it making much of a difference between material types. Silicone, Tygon, and cheap imitations all work. On longer runs the tubing affects instrument dynamics. The more tubing is elastic, or the longer it is, the more it will delay and slow down the responses.
Size is a little more difficult to chose. If the probe orifice is large, a bigger diameter tube will transmit changes faster. If the orifice is small, the capacity/volume of the tube will form a filter against the source resulting in delayed and slowed indications of change indicating use of a narrower tube.

-Wit, HZ

[krasw]

Anything put over pvc or silicone tube just creates leaks.

[Robert Seccombe SE3]

That's what I used.
https://drive.google.com/file/d/1Kg5E3drPscRNgk1jKFH9CSxY3EJs62rU/view?usp=drivesdk