REFLECTOR: Site gage tube tore like wet cardboard, YIKES

[Laurence Coen]

Ken,

I had my own "YIKES" with the sight gauge material I got with the kit.  I do 
not think what went wrong had to do with fuel exposure.  I got my kit in '95 
and it was close to 10 years before my sight gauges saw there first drop of 
fuel.  During this period, the tubing turned yellow and was quite opaque.  I 
replaced it with plain old vinyl tubing  because I couldn't see the fuel 
level.  Upon removal, the tubing fell apart and was the consistency of 
chewing gum.  Vinyl tubing when exposed to fuel hardens due to the leaching 
of plasticizers but it doesn't turn yellow or become opaque.  Left in 
service it will turn into a rigid sight gauge.  At $0.65 per foot I opt to 
replace at annual.  Vinyl tubing also carries a date of manufacture printed 
on it so you can tell if you're getting fresh.

Larry Coen
N136LC

--------------------------------------------------
From: "Ken C. Baker" <kenb at velocityaircraft.com>
Sent: Wednesday, May 21, 2008 7:27 PM
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Subject: Re: REFLECTOR: Site gage tube tore like wet cardboard, YIKES

> All,
>
> I'm not sure which type of polyethylene tubing that spruce supplies,
> but there are many many variants on the market with many different
> physical and chemical properties. The style of tubing that is shipped
> with Velocity kits is a Tygon product called Tygothane.
>
> Best,
>
> -Ken
>
>
>
> On May 21, 2008, at 8:05 PM, Tom <tomcat05 at comcast.net> wrote:
>
>> I recently replaced with the aircraft spruce polyethylene which was
>> already mentioned. Got that info from Scott Swing and it is what the
>> factory uses.
>> I put small corks (painted orange) in the lines which affords good
>> visibility of the fuel levels.
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