Barking Sands
Guru
- Joined
- Dec 24, 2019
- Messages
- 981
- Location
- New Port Richey, Fl
- Vessel Name
- M/V Intrigue
- Vessel Make
- 1985 Tung Hwa Senator
Nice job! I am interested in your experience based comment on Tygon. When I purchased my current boat 4 years ago the sight gauges were nylon hose. These were picked out by my surveyor and after purchase I replaced with Tygon fuel rated hose. My sight gauges are nicely located and with a huge engine room am happy with this arrangement. However your comment re Tygon failing concerns me. Can you add context please? FYI I generally close the sight gauge valves but have certainly left them open from time to time and am wondering if this is safe.
~A
If you take a look at this old thread you can see the OP found and slightly cracked sight tube. I dont know if this was Tygon or not but this is generally how they crack.
https://www.trawlerforum.com/forums/s32/fuel-tank-sight-tube-valves-54397-2.html
Dont get me wrong. Tygon is excellent hose and can last years. But they will eventually crack and leak.
On certain models of aircraft the inspection interval for what is called an Engine Minor inspection is every 200 hours. Essentially every couple of months depending on schedule. At that time a mechanic will uncowl the entire engine and closely examine everything. Every separate item is written up as a "squawk". He may be allotted 10 hours per engine. When done the inspector comes behind him and looks again. So generally everything is found. Keep in mind we have hundreds of aircraft come and go every year that are at different stages of life. So some of the Tygon that is found cracked could be years old. But probably not more than 5 years. Also keep in mind the conditions are a bit harsher. Aslo keep in mind Tygon is ONLY Used for drains. One end is usually attached to gang drain manifold and drains overboard. But still we find them broken at the clamp routinely and change it "on condition".
The other more critical hoses are changed every 5 years regardless of condition. I have many old hoses in my garage to use for various things from these scheduled hose changes
If I had sight tubes and was using Tygon I would apply the following for safety:
1) Keep valves closed when not checking levels
2) Put the changing of the Tygon sight tube on a scheduled interval along with oil changes and other scheduled items. I would probably make it every 2 years or maybe even 3.
3) Dont over tighten the clamps. This surely causes premature failure
4) take a close look at them every now and then with a flashlight and look for cracking just like in the link. Usually at the barb end or right at the clamp.
I dont mean to poo poo sight tubes and Tygon at all. Just apply a bit of logic and a slight change of thinking to include those tubes in your routine Mx and inspection. For many it seems to be a set it and forget it type of thing or out of sight out of mind. That is until it leaks and you also leave the valves open 24/7/365
And of course the above is just an opinion from my own experiences.
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