Today's Message Index:
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0. 12:19 AM - Coming Soon - The List of Contributors - Please Make A Contribution Today! (Matt Dralle)
1. 05:45 AM - Re: epoxy (jerzy krasinski)
2. 06:55 AM - Re: epoxy (ALFRED ROSA)
3. 08:57 AM - Re: epoxy (Richard Trickel)
4. 11:37 PM - Fuel level sender repair? (Jason Hills)
Message 0
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| Subject: | Coming Soon - The List of Contributors - Please Make A Contribution |
Today!
Each year at the end of the List Fund Raiser, I post a message acknowledging everyone
that so generously made a Contribution to support the Lists. Its my way
of publicly thanking everyone that took a minute to show their appreciation
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Message 1
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There is a very general law in chemistry called Arrhenius law, saying that
the =0Aspeed of chemical destruction of whatever molecules-decreases expo
nentially =0Awith-reducing temperature ( it also decreases exponentially
with increase of =0Aactivation energy of that molecule, but we can not chan
ge that for a given =0Aepoxy) . =0A=0A=0AIn simple words it means that you
approximately double the lifetime-for every-10 =0Adegrees centigrade of
temperature reduction. =0A=0ASo, keeping it in a refrigerator at zero cent
igrade (20 degrees temperature =0Areduction) would increase the lifetime by
a factor of four. Holding it in a =0Afreezer-(thirty or more degrees tem
perature reduction) would -increase the =0Alifetime by a factor of eight
or more, depending on temperature.=0A=0AAll that is true, but there is more
to it. If the stuff is a mixture of a few =0Achemicals you might experienc
e separation of these chemicals at low temperature =0Aand the stuff can bre
ak into layers. That does not mean that it got spoiled, but =0Ayou would ha
ve to mix it again well after reheating to room temperature before =0Afutur
e use.=0ALuckily, epoxy has high viscosity, which increases fast with cooli
ng. It would =0Abe a solid in- a freezer, and solids do not separate. Fas
t cooling would reduce =0Athe risc of separation even further.=0AJerzy=0AIs
it OK to keep resin in the freezer to extend shelf life for a year or more
. =0A-Or does that degrade it. =0A=0A=0A________________________________
=0A=0AFrom: ALFRED ROSA <fredorosa@gmail.com>=0ATo: kisbuilders <kis-list@m
atronics.com>=0ASent: Mon, November 8, 2010 12:10:05 PM=0ASubject: KIS-List
============ =0A
Message 2
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Thanks Jerzy. Certainly more economical to get a gallon of resin instead of
quarts when you need it. I'll keep a quart out and freeze the rest.
Al
On Tue, Nov 9, 2010 at 8:41 AM, jerzy krasinski <
jerzy_krasinski@sbcglobal.net> wrote:
> There is a very general law in chemistry called Arrhenius law, saying that
> the speed of chemical destruction of whatever molecules decreases
> exponentially with reducing temperature ( it also decreases exponentially
> with increase of activation energy of that molecule, but we can not change
> that for a given epoxy) .
>
> In simple words it means that you approximately double the lifetime for
> every 10 degrees centigrade of temperature reduction.
> So, keeping it in a refrigerator at zero centigrade (20 degrees temperature
> reduction) would increase the lifetime by a factor of four. Holding it in a
> freezer (thirty or more degrees temperature reduction) would increase the
> lifetime by a factor of eight or more, depending on temperature.
>
> All that is true, but there is more to it. If the stuff is a mixture of a
> few chemicals you might experience separation of these chemicals at low
> temperature and the stuff can break into layers. That does not mean that it
> got spoiled, but you would have to mix it again well after reheating to room
> temperature before future use.
> Luckily, epoxy has high viscosity, which increases fast with cooling. It
> would be a solid in a freezer, and solids do not separate. Fast cooling
> would reduce the risc of separation even further.
> Jerzy
> ------------------------------
> *From:* ALFRED ROSA <fredorosa@gmail.com>
> *To:* kisbuilders <kis-list@matronics.com>
> *Sent:* Mon, November 8, 2010 12:10:05 PM
> *Subject:* KIS-List: epoxy
>
> Is it OK to keep resin in the freezer to extend shelf life for a year or
> more. Or does that degrade it.
>
> Al
>
> *www.aeroelectric.com
> omebuiltHELP <http://www.homebuilthelp.com/>*
>
> *
>
>
Message 3
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I would email the manufacture.with this question.- I have done it myself
but never kept it in for a long period of time
Rich
--- On Tue, 11/9/10, jerzy krasinski <jerzy_krasinski@sbcglobal.net> wrote:
From: jerzy krasinski <jerzy_krasinski@sbcglobal.net>
Subject: Re: KIS-List: epoxy
There is a very general law in chemistry called Arrhenius law, saying that
the speed of chemical destruction of whatever molecules-decreases exponen
tially with-reducing temperature ( it also decreases exponentially with i
ncrease of activation energy of that molecule, but we can not change that f
or a given epoxy) .
-
In simple words it means that you approximately double the lifetime-for e
very-10 degrees centigrade of temperature reduction.
So, keeping it in a refrigerator at zero centigrade (20 degrees temperature
reduction) would increase the lifetime by a factor of four. Holding it in
a freezer-(thirty or more degrees temperature reduction) would -increas
e the lifetime by a factor of eight or more, depending on temperature.
-
All that is true, but there is more to it. If the stuff is a mixture of a f
ew chemicals you might experience separation of these chemicals at low temp
erature and the stuff can break into layers. That does not mean that it got
spoiled, but you would have to mix it again well after reheating to room t
emperature before future use.
Luckily, epoxy has high viscosity, which increases fast with cooling. It wo
uld be a solid in- a freezer, and solids do not separate. Fast cooling wo
uld reduce the risc of separation even further.
Jerzy
From: ALFRED ROSA <fredorosa@gmail.com>
Sent: Mon, November 8, 2010 12:10:05 PM
Subject: KIS-List: epoxy
Is it OK to keep resin in the freezer to extend shelf life for a year or mo
re. -Or does that degrade it.
Alwww.aeroelectric.com
omebuiltHELP
=0A=0A=0A
Message 4
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| Subject: | Fuel level sender repair? |
Last night I tracked down problems with my left fuel level to the sender in the tank. The sender is a Westach 395-5S (http://www.aircraftspruce.com/catalog/inpages/westfuelqty2.php) or similar. I've confirmed the wiring to it is good, but the output resistance "never" changes as the fuel level changes (it is known to work intermittently actually, and based on the reading I'm seeing, I suspect that the probe is shorting out when it stops working).
So, not having built this plane, I don't really know if replacement is realistic
or not... I suspect the probe is secured inside the wing/tank towards the inboard
end of the tank, plus the head is bolted to the outboard end of the tank
(accessible through an inspection plate). My best guess is that the top of the
wing would have to be cut into to gain access to the far end and then the top
of the wing would have to be re-glassed and painted. Yikes!
I'm not about to do this myself, but conceivably I could have my A&P who worked
at Glassair in the past do it (i.e. he's pretty good with glasswork, even if
he prefers working on RV's).
I've lived with this issue for a long time, but having just installed a new engine
monitor (JPI EDM 740) getting the fuel probes setup and working was a major
ordeal, and now I should be able to get fairly accurate tank readings compared
to the old analog gauge which was basically only really good for "full", "empty"
or "somewhere in between". I finally got the EDM talking to the right tank
last night and confirmed that the left tank was not behaving the same as the
right as I added/removed fuel.
Any recommendations?
Thanks!
...Jason
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