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A Safe Solvent

R

Randy Gross

Jan 1, 1970
0
Greetings,

Has anyone used, or know of, a safe method/solvent for removing varnish
from windings that won't ruin the insulation?

Randy Gross
 
F

Fritz Schlunder

Jan 1, 1970
0
Randy Gross said:
Greetings,

Has anyone used, or know of, a safe method/solvent for removing varnish
from windings that won't ruin the insulation?

Randy Gross


To the best that I've been able to ascertain plain old over the counter ~70%
concentration rubbing (isopropyl) alcohol seems to make the varnish all
rubbery without damaging the insulation. Certainly my testing methods of
the winding enamel haven't been scientific in the slightest being that I
hold the belief new wire is a good investement. A basic resistance
measurement along with physically scratching the enamel test were the extent
of my investigations. In those tests it seemed to me the enamel was pretty
much the same as it was prior to exposure to the rubbing alcohol. YMMV with
different enamel insulations and more scientific testing.

Unless you heat the alcohol it will take a very long time to make a
significant impact on the varnish (likely in the days to weeks range). I've
sucessfully used a sealed jar heated on a stovetop to about 100 deg. C in a
pot of water to heat the alcohol to accelerate the process. It takes less
than 30 minutes of heating to achieve good results. Not everyone likes the
sounds of this idea on the grounds that it sounds risky to them. Rubbing
alcohol boils at under 100 deg. C (at 1 atm pressure) so it must be enclosed
in a sealed container with enough integrity not to burst or leak
significantly. Isopropyl alcohol of 70% or more is flammable (and perhaps
with just the right stoichiometric mix somewhat explosive) so keep that in
mind.
 
M

Mac

Jan 1, 1970
0
To the best that I've been able to ascertain plain old over the counter ~70%
concentration rubbing (isopropyl) alcohol seems to make the varnish all
rubbery without damaging the insulation. Certainly my testing methods of
the winding enamel haven't been scientific in the slightest being that I
hold the belief new wire is a good investement. A basic resistance
measurement along with physically scratching the enamel test were the extent
of my investigations. In those tests it seemed to me the enamel was pretty
much the same as it was prior to exposure to the rubbing alcohol. YMMV with
different enamel insulations and more scientific testing.

Unless you heat the alcohol it will take a very long time to make a
significant impact on the varnish (likely in the days to weeks range). I've
sucessfully used a sealed jar heated on a stovetop to about 100 deg. C in a
pot of water to heat the alcohol to accelerate the process. It takes less
than 30 minutes of heating to achieve good results. Not everyone likes the
sounds of this idea on the grounds that it sounds risky to them. Rubbing
alcohol boils at under 100 deg. C (at 1 atm pressure) so it must be enclosed
in a sealed container with enough integrity not to burst or leak
significantly.

It doesn't seem THAT dangerous on an electric range. But on a gas range,
it seems too dangerous to be reasonable.

What scares me the most about it is that if the container fails
catastrophically, you will have a sudden burst of alcohol vapor in close
proximity to an open flame with no time to react. It could definitely
start a fire, singe some hair, or maybe even blow out a window.

It would be much safer to do this without the hot-water bath but with a
lab-supply hot-plate. I'd still make sure I had a large fire-extinguisher
handy.

Come to think of it, I don't think I would do this even with an electric
range. Not worth the risk.
Isopropyl alcohol of 70% or more is flammable (and perhaps
with just the right stoichiometric mix somewhat explosive) so keep that in
mind.

Alcohol vapor mixed with air is super flammable. If the fuel/air mix is
just right, a cup (~250mL) could probably blow the roof off of your house.
At any rate, I've heard that a quarter cup of gasoline, totally vaporized,
and mixed properly with air, is equivalent to one stick of TNT. I don't
know how true it is, but I think alcohol has at least 50% of the chemical
potential energy as gasoline, and it is easier to ignite.

Mac
--
 
J

Jeff

Jan 1, 1970
0
Mac said:
It doesn't seem THAT dangerous on an electric range. But on a gas range,
it seems too dangerous to be reasonable.

What scares me the most about it is that if the container fails
catastrophically, you will have a sudden burst of alcohol vapor in close
proximity to an open flame with no time to react. It could definitely
start a fire, singe some hair, or maybe even blow out a window.

It would be much safer to do this without the hot-water bath but with a
lab-supply hot-plate. I'd still make sure I had a large fire-extinguisher
handy.

Come to think of it, I don't think I would do this even with an electric
range. Not worth the risk.


Alcohol vapor mixed with air is super flammable. If the fuel/air mix is
just right, a cup (~250mL) could probably blow the roof off of your house.
At any rate, I've heard that a quarter cup of gasoline, totally vaporized,
and mixed properly with air, is equivalent to one stick of TNT. I don't
know how true it is, but I think alcohol has at least 50% of the chemical
potential energy as gasoline, and it is easier to ignite.

Gasoline has about 38,000 kj/l worth of energy. A 1/4 cup of gasoline would
therfore contain about 10,000 kj. If vaporized, and properly mixed with air,
it would almost burn instantly. Anyone know how much energy is in a stick of
TNT?
 
H

Howard Henry Schlunder

Jan 1, 1970
0
Gasoline has about 38,000 kj/l worth of energy. A 1/4 cup of gasoline would
therfore contain about 10,000 kj. If vaporized, and properly mixed with air,
it would almost burn instantly. Anyone know how much energy is in a stick of
TNT?

http://octopus.gma.org/surfing/weather/andypwer.pdf displays 4.2x10^15 Joules/megaton of TNT, which implies there are 46,000 kJ/kg in TNT. I have no idea how much mass is in a stick of TNT, but if we assume it is 1/4kg (12,000 kJ), then 1/4 cup of gasoline works out as a reasonable comparison.
 
H

Howard Henry Schlunder

Jan 1, 1970
0
Alcohol vapor mixed with air is super flammable. If the fuel/air mix is
just right, a cup (~250mL) could probably blow the roof off of your house.
At any rate, I've heard that a quarter cup of gasoline, totally vaporized,
and mixed properly with air, is equivalent to one stick of TNT. I don't
know how true it is, but I think alcohol has at least 50% of the chemical
potential energy as gasoline, and it is easier to ignite.

Although my calculations do agree that alcohol has somewhere around 50% of the energy storage of gasoline and that gasoline is comparable to TNT, I seriously don't think anyone needs to worry about explosions removing roofs or windows from your home. It simply won't happen with 30% water contamination using ambient air (versus a pure oxygen atmosphere or a highly compressed, properly mixed internal combustion engine). If you read various sites, such as [ http://www.violetwand.org/fire.htm ], there is evidence that people ignite alcohol on their signficant others using Tesla wands in their bedrooms/torcher chambers. If a human body can withstand an alcohol fire, I should think a stove top/floor/etc. could as well (assuming someone is actively paying attention to it).
 
N

N. Thornton

Jan 1, 1970
0
Fritz Schlunder said:
Unless you heat the alcohol it will take a very long time to make a
significant impact on the varnish (likely in the days to weeks range). I've
sucessfully used a sealed jar heated on a stovetop to about 100 deg. C in a
pot of water to heat the alcohol to accelerate the process. It takes less
than 30 minutes of heating to achieve good results. Not everyone likes the
sounds of this idea on the grounds that it sounds risky to them. Rubbing
alcohol boils at under 100 deg. C (at 1 atm pressure) so it must be enclosed
in a sealed container with enough integrity not to burst or leak
significantly. Isopropyl alcohol of 70% or more is flammable (and perhaps
with just the right stoichiometric mix somewhat explosive) so keep that in
mind.


Fritz, the OP said safe :)

Regards, NT
 
T

Tim Shoppa

Jan 1, 1970
0
Fritz Schlunder said:
Rubbing
alcohol boils at under 100 deg. C (at 1 atm pressure) so it must be enclosed
in a sealed container with enough integrity not to burst or leak
significantly.

If it does leak, it just evaporates. I'm all for safety and using
proper containers, but it's just not that big a deal. As it evaporates,
the alcohol goes away before the water... leaving you with water.

Now, if you're going to be heating a sealed container of isopropyl,
that's a different safety matter. I would rather have the container
fail at low pressure than at high pressure!

Tim.
 
R

Randy Gross

Jan 1, 1970
0
I can see from this discussion, by general consensus, that the method works
and, there is an element of danger. I agree that the container should be
capable of pressure relief and can be as simple as a drilled hole in the
cap, covered with a rubber flap, and enough weight applied to maintain a
reasonable level of pressure. Vented vapor can be routed away from the heat
source or, better yet, boil this wicked brew in Mother Natures' kitchen.

Thanks Guys,

Randy Gross




















<[email protected]>...
: > Rubbing
: > alcohol boils at under 100 deg. C (at 1 atm pressure) so it must be
enclosed
: > in a sealed container with enough integrity not to burst or leak
: > significantly.
:
: If it does leak, it just evaporates. I'm all for safety and using
: proper containers, but it's just not that big a deal. As it evaporates,
: the alcohol goes away before the water... leaving you with water.
:
: Now, if you're going to be heating a sealed container of isopropyl,
: that's a different safety matter. I would rather have the container
: fail at low pressure than at high pressure!
:
: Tim.
:
 
R

R. Steve Walz

Jan 1, 1970
0
Howard said:
in message
displays 4.2x10^15 Joules/megaton of TNT, which implies there are 46,000 kJ/kg in TNT. I have no idea how much mass is in a stick of TNT, but if we assume it is 1/4kg (12,000 kJ), then 1/4 cu
-------------
That is correct, liquid petroleate fuels are near the highest energy
densities, well above solid explosives, even pure organic nitrates.
That is why kerosine and liquid oxygen is still the second most powerful
fuel for rockets next to pure H2 and O2.

-Steve
 
R

R. Steve Walz

Jan 1, 1970
0
Howard said:
"Mac" wrote in message news:p[email protected]
------------
Actually it depends totally on the conditions of combustion, since
alcohol evaporates off any surface due to its own combustion
temperatures, whereas if prevented from doing so, for instance
with a focused torch or liquid fuel engine, could immolate a
human body all the way to ammonia, mineral oxides, H2O, and CO2.

-Steve
 
C

Chris Carlen

Jan 1, 1970
0
Howard said:
in message
Alcohol vapor mixed with air is super flammable. If the fuel/air
mix is just right, a cup (~250mL) could probably blow the roof off
of your house. At any rate, I've heard that a quarter cup of
gasoline, totally vaporized, and mixed properly with air, is
equivalent to one stick of TNT. I don't know how true it is, but I
think alcohol has at least 50% of the chemical potential energy as
gasoline, and it is easier to ignite.


Although my calculations do agree that alcohol has somewhere around
50% of the energy storage of gasoline and that gasoline is comparable
to TNT, I seriously don't think anyone needs to worry about
explosions removing roofs or windows from your home. It simply won't
happen with 30% water contamination using ambient air (versus a pure
oxygen atmosphere or a highly compressed, properly mixed internal
combustion engine). If you read various sites, such as [
http://www.violetwand.org/fire.htm ], there is evidence that people
ignite alcohol on their signficant others using Tesla wands in their
bedrooms/torcher chambers. If a human body can withstand an alcohol
fire, I should think a stove top/floor/etc. could as well (assuming
someone is actively paying attention to it).


Hydrocarbon fuels will have much greater energy per mass than high
explosives. It is the rate of energy release of explosives that gives
them their kick. They acheive the highest peak power outputs compared
to other chemical energy sources, but lower total energy outputs.

An analogy is high power pulsed lasers. I work with lasers that can
easily exceed the 220 Megawatts power output level. That's right, I
said 220 MW!!!

But since the pulse only lasts 8ns, the total energy delivered is about
1.76J. But the high rate of energy delivery, coupled with delivering
that energy over a very small area, translates into considerable
destructive power. These sorts of lasers can blow holes in metal sheets
and optical elements.

Check out these photos for an example:

http://home.earthlink.net/~crobc/laser-photos/index.htm

The red and blue lasers in these photos are a dramatization. The laser
that actually blew the window (about 1" dia. x 1/8" thick crystalline
quartz) was invisible 266nm UV radiation at about 16 MW .


Good day!
 
K

Keith R. Williams

Jan 1, 1970
0
-------------
That is correct, liquid petroleate fuels are near the highest energy
densities, well above solid explosives, even pure organic nitrates.
That is why kerosine and liquid oxygen is still the second most powerful
fuel for rockets next to pure H2 and O2.

IIRC, F2 and H2 have the highest specific impulse of any chemical
reaction. O2 and petroleum fuels are in the 250S range, while H2
&F2 are close to 400. However, F is rather nasty stuff (being the
most electronegative of all elements) thing to deal with, in just
about every way. F2 has been used as rocket propellant though.
 
B

Bob Masta

Jan 1, 1970
0
Hydrocarbon fuels will have much greater energy per mass than high
explosives. It is the rate of energy release of explosives that gives
them their kick. They acheive the highest peak power outputs compared
to other chemical energy sources, but lower total energy outputs.

As I recall, the military was experimenting a while back with
weapons that used air and fuel, with some means of volatilizing
the fuel to some optimum state just before ignition. Haven't
heard anything about this in a while, so I don't know if this is
still ongoing. I think Hollywood also picked up on this project
a few years back for a Dustin Hoffman movie where the
military was going to use one of these weapons to destroy
a town infected with a virus.



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
 
K

Keith R. Williams

Jan 1, 1970
0
As I recall, the military was experimenting a while back with
weapons that used air and fuel, with some means of volatilizing
the fuel to some optimum state just before ignition. Haven't
heard anything about this in a while, so I don't know if this is
still ongoing.

Sure. FAE's are still around. These are one type of hyperbaric
explosives (primary damage is by over-pressure). The "daisy-
cutters" are another. In Desert Storm the US used them on Iraq.
The story was that the Brit field commanders thought the US had
gone nuclear when they were used. Indeed they've been called the
"poor man's nuke".
I think Hollywood also picked up on this project
a few years back for a Dustin Hoffman movie where the
military was going to use one of these weapons to destroy
a town infected with a virus.

Seems reasonable, for Hollywood.
 
F

Fritz Schlunder

Jan 1, 1970
0
Bob Masta said:
As I recall, the military was experimenting a while back with
weapons that used air and fuel, with some means of volatilizing
the fuel to some optimum state just before ignition. Haven't
heard anything about this in a while, so I don't know if this is
still ongoing. I think Hollywood also picked up on this project
a few years back for a Dustin Hoffman movie where the
military was going to use one of these weapons to destroy
a town infected with a virus.


Yeah they were wrong in that movie (was it called Outbreak?). Fuel Air
Explosives aren't the most powerful non-nuclear weapon in the US arsenal.
Rather the MOAB (Mother Of All Bombs, aka, Massive Ordinance Air Burst) is.
IIRC the MOAB has a yeild of something like 25 tons of TNT, whereas
Hiroshima had a yeild of about 14.5 kilotons of TNT. Still a far cry from
even relatively small nuclear bombs, but they do make much smaller nuclear
bombs than used on Hiroshima.

For some extra reading:

http://www.twin-towers.net/moab_bomb.htm

http://www.opendemocracy.net/debates/article-2-88-1028.jsp
 
K

Keith R. Williams

Jan 1, 1970
0
IIRC, the Russians (Germans) were experimenting with H2-F2
engines in the early 50's, IIRC. The US had some research here
too. Enough research that both sides built production
capabilities for F2. Both (eventually) found the hazards of a
rocket full of F2 falling where one didn't want it (at the time
this was a frequent occurrence), outweighed the advantages.

HFL is a similar nasty that has been used.
 
K

Keith R. Williams

Jan 1, 1970
0
Yeah they were wrong in that movie (was it called Outbreak?). Fuel Air
Explosives aren't the most powerful non-nuclear weapon in the US arsenal.
Rather the MOAB (Mother Of All Bombs, aka, Massive Ordinance Air Burst) is.
IIRC the MOAB has a yeild of something like 25 tons of TNT, whereas
Hiroshima had a yeild of about 14.5 kilotons of TNT. Still a far cry from
even relatively small nuclear bombs, but they do make much smaller nuclear
bombs than used on Hiroshima.

I suppose since MOAB is a hyperbaric bomb, it could be considered
an FAE (it is fuel rich, so does depend on air, and do go bang).
I hadn't considered this angle on FAE before though. Perhaps
this is where they're going?
 
M

Mac

Jan 1, 1970
0
Although my calculations do agree that alcohol has somewhere around 50%
of the energy storage of gasoline and that gasoline is comparable to
TNT, I seriously don't think anyone needs to worry about explosions
removing roofs or windows from your home. It simply won't happen with
30% water contamination using ambient air (versus a pure oxygen
atmosphere or a highly compressed, properly mixed internal combustion
engine). If you read various sites, such as [
http://www.violetwand.org/fire.htm ], there is evidence that people
ignite alcohol on their signficant others using Tesla wands in their
bedrooms/torcher chambers. If a human body can withstand an alcohol
fire, I should think a stove top/floor/etc. could as well (assuming
someone is actively paying attention to it).
"Mac" wrote in message news:p[email protected]

Well, I never said anything about anyone getting hurt, other than singed
hair, but it doesn't take much pressure to blow out a window in your
house. I admit that blowing the roof off is not very likely, unless your
house is small and tightly sealed.

Also, the scenario I'm envisioning is one where the alcohol is in, say, a
glass jar. The alcohol, at 100 C, builds up enough pressure to rupture the
jar (I don't know if this is likely -- depends on the pp of isopropanol at
100 C, I guess). Now, released from the pressure of the jar, the alcohol
vaporizes instantly, and mixes in with the air. Shortly after rupturing,
the fuel-air mix is ignited by the flame of the burner. The combustion
releases a lot of energy, and I could see it breaking a window, if the
window were close and closed. I definitely wouldn't expect anyone to die
(except maybe in the subsequent fire).

Anyway, I guess we've gotten pretty far afield from electronics. ;-)

Mac
--
 
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