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budyerly(at)msn.com
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 Posted: Thu Aug 21, 2008 9:20 am Post subject: Ethanol and sight tubes. |
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<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Sorry I couldn't weigh in on the site lately, too much work and too little time.
You can go to my website at customflightcreations.com and select accessories to see how I do my sight tubes. They all work very well between the seats.
Back to ethanol... I finished a test on a 10% ethanol 92 octane fuel and its effects on our polyurethane tubing, and acrylic plexiglass.
To my surprise, the ethanol fuel really made the polyurethane yellow faster. After prolonged exposure, the urethane did not seem to deteriorate at all. However, within two hours, the yellowing of the tube became pronounced. I frankly looked pretty dark after a week, but it was readable and held up well.
I then tested it with a new rigid acrylic tube, which by the tech data, was supposed to be safe for use with gasoline, and fair with pure ethanol. After only two hours, the acrylic began to break down in the 10% fuel mixture. By the end of 8 hours it began become slightly opaque and slimy where the fuel contacted. I then cut a piece of the tubing and submerged it completely. Sure enough, the tube outer part became a slimy mess, but it was still rigid, although un-useable. So please pretest your acrylics.
Redux (Epibond or Araldite 420 A/B) held up pretty well. The glue had cured for only 12 hours and was submersed. No significant change noticed. Pro Seal was OK but the manufacturer has only tested it to 10% ethanol in fuel, and I noticed a slightly slimy surface, but it still stuck very well with prolonged exposure.
My lessons learned are to make the urethane sight tube easy to replace on the annual inspection and stick with the urethane tube. The FAA requires some sort of visual fuel check before flight, so it works for me. Plumbed the way I show it in my website, allows it to be useful in flight also. Electronically, I use the capacitance fuel probes for fuel measuring with a Mitchell or similar gauge and calibrate the probe at 0-5-10-and 15 gallons to correspond to the 1/4,1/2,3/4, full, points. I must admit, that changing the face of the gauge is the way to go. I do it in shop and should have Mitchell change the face on a custom order. They will do it for a price.
Thought this may be of interest.
Bud Yerly
Custom Flight Creations
(813) 653-4989
[quote][b]
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topglock(at)cox.net
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| Posted: Thu Aug 21, 2008 10:38 am Post subject: Ethanol and sight tubes. |
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I've used ethanol to help dye certain clear plastics. It definitely has
a penetrating effect. Looks like a shielded glass may be the way to go,
for sight gauges...
Jeff
ALAN YERLY wrote:
| Quote: | Sorry I couldn't weigh in on the site lately, too much work and too
little time.
You can go to my website at customflightcreations.com and select
accessories to see how I do my sight tubes. They all work very well
between the seats.
Back to ethanol... I finished a test on a 10% ethanol 92 octane fuel
and its effects on our polyurethane tubing, and acrylic plexiglass.
To my surprise, the ethanol fuel really made the polyurethane yellow
faster. After prolonged exposure, the urethane did not seem to
deteriorate at all. However, within two hours, the yellowing of the
tube became pronounced. I frankly looked pretty dark after a week, but
it was readable and held up well.
I then tested it with a new rigid acrylic tube, which by the tech data,
was supposed to be safe for use with gasoline, and fair with pure
ethanol. After only two hours, the acrylic began to break down in the
10% fuel mixture. By the end of 8 hours it began become slightly opaque
and slimy where the fuel contacted. I then cut a piece of the tubing
and submerged it completely. Sure enough, the tube outer part became a
slimy mess, but it was still rigid, although un-useable. So please
pretest your acrylics.
Redux (Epibond or Araldite 420 A/B) held up pretty well. The glue had
cured for only 12 hours and was submersed. No significant change
noticed. Pro Seal was OK but the manufacturer has only tested it to 10%
ethanol in fuel, and I noticed a slightly slimy surface, but it still
stuck very well with prolonged exposure.
My lessons learned are to make the urethane sight tube easy to replace
on the annual inspection and stick with the urethane tube. The FAA
requires some sort of visual fuel check before flight, so it works for
me. Plumbed the way I show it in my website, allows it to be useful in
flight also. Electronically, I use the capacitance fuel probes for fuel
measuring with a Mitchell or similar gauge and calibrate the probe at
0-5-10-and 15 gallons to correspond to the 1/4,1/2,3/4, full, points. I
must admit, that changing the face of the gauge is the way to go. I do
it in shop and should have Mitchell change the face on a custom order.
They will do it for a price.
Thought this may be of interest.
Bud Yerly
Custom Flight Creations
(813) 653-4989
*
*
Checked by AVG - http://www.avg.com
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budyerly(at)msn.com
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| Posted: Fri Aug 22, 2008 7:53 am Post subject: Ethanol and sight tubes. |
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<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Jeff,
You have hit the nail on the head. I'm looking to make a fitting using tempered glass, but am still a little shy about producing one until fully tested.
Just like my tow bar, it took three different designs to finally get it right. I figure the same problem with the protected glass sight tube idea and the final cowl changes.
So many ideas, and so little time.
See you at Rough River if you don't get drowned out by Fay.
Bud
Custom Flight Creations
www.customflightcreations.com
(813) 653-4989
[quote] ---
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