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OfflineMadtowntripper
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Simple Chemistry/Physics Question
    #8911785 - 09/11/08 10:28 AM (15 years, 8 months ago)

I work at an airport in a pretty wintry and cold place in the northern US.  Every winter I'm a member of our de-ice crew here and can usually be found on a 30-foot boom in -10 degree weather soaked to the skin with our de-icing agent, which is Propylene Glycol.

We have two main types of fluid we use, a de-ice and an anti-ice.  The de-ice is thin and watery and we spray it from a high-pressure nozzle, like a fire hose.  You can shoot the spray 100 feet in a nice tight stream.

But my question is about the anti-ice.  This is a thick gloopy substance, like honey.  This is sprayed from something very similar to a large-diameter low-pressure garden hose.  When it comes out it sticks to the aircraft wings because of it's high viscosity.  But the viscosity changes when it is put under a shear stress, like when the airplane is in motion.  Shearing this fluid causes it to become extremely low viscosity and it just slides off and the plane can fly.

Now, it's getting cold here and last night we were out getting the trucks ready to go.  We had 4,000 gallons of our anti-ice fluid in the truck and someone accidentally hit the "Pump" button, which causes the high-pressure pump to start circulating all of this fluid through.  But that pump is only for the de-ice solution, because apparently the pressure caused excessive shear stress to the anti-ice fluid and it's now worthless.  We dumped out 4,000 gallons @ $7 per gallon.  The people at the fuel farm where we get it told me that you can let this fluid sit for a few months and it will slowly regain it's original sticky properties.

But I guess my question is; How is this possible?  I really hated chemistry and physics in school, and I know this something to do with one or the other.  Are these Newtonian fluids, or non-Newtonian fluids?  What allows them to, upon being subjected to a shear-stress, to have such an extreme change in viscosity?  Is it due to some kind of polymer in the fluid, or is this is a property of the fluid itself?

I'm sure one of you can answer this for me...


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After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action.  If you cannot throw it at least you can always drink out of it.  - Ernest Hemingway

If it is life that you feel you are missing I can tell you where to find it.  In the law courts, in business, in government.  There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent.    -Cormac MacCarthy

He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God.  - Aeschylus

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OfflineBrainChemistry
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Re: Simple Chemistry/Physics Question [Re: Madtowntripper]
    #8911876 - 09/11/08 10:49 AM (15 years, 8 months ago)

I probably can't fully answer your question, but heres a little bit of info.

Different liquids have different resistance to shear stress. The ratio of shear stress to shear rate (or strain) is called the Young's Modulus (i'm pretty sure on that...i'm recalling from a class I took last year). Its simply a property of the material resistance to deformation.

Some "liquids" are actually solids until they are subjected to a shearing force. They are called Bingham plastics. An example of this would be toothpaste or mayo.

This anti-ice stuff you're talking about just sounds like it has a fairly high young's modulus (for a liquid), such that it is very viscous until you push on it.

A newtonian fluid is simply a fluid with a linear shear stress/strain rate. Its possible that the stuff you're using isn't Newtonian when you fire it out of the hose, but once the plane is in the air, it flows like one.

Hope that helped! :super:


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Word to your mom.

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OfflineMadtowntripper
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Re: Simple Chemistry/Physics Question [Re: BrainChemistry]
    #8911887 - 09/11/08 10:54 AM (15 years, 8 months ago)

Yeah, I am vaguely familiar with Young's Modulus from a Structural Geology course...


--------------------
After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action.  If you cannot throw it at least you can always drink out of it.  - Ernest Hemingway

If it is life that you feel you are missing I can tell you where to find it.  In the law courts, in business, in government.  There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent.    -Cormac MacCarthy

He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God.  - Aeschylus

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Invisiblejohnm214
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Re: Simple Chemistry/Physics Question [Re: Madtowntripper]
    #8912479 - 09/11/08 01:16 PM (15 years, 8 months ago)

My guess is similar to the one above.


I would guess the compound is some polymer that sticks to other molecules of itself.  So when you mix it up real good it can cut some of the bonds and allow the polymers to slide past one another and break their connections/associations with one another and become more liquid.  After sitting a while the polymers will begin to reform bonds and associations and become more solidified again.


Seems similar to rubber.  Natural rubber polymers will simply slide past each other and disintegrate under some forces.  While I believe this is an irreverable process, rubber is also much more solid than the agent you use.  When you vulcanize rubber I believe you form sulfer bonds between adjacent polymer molecules and thus stop the slipping of the polymer past each other.


I'd guess its a similar process with a much more free flowing agent, so that when you stir it up it becomes more fluid, but it can settle and reform bonds/associations with adjacent molecules and become more solidified.

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InvisibleMinstrel
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Re: Simple Chemistry/Physics Question [Re: johnm214]
    #8912889 - 09/11/08 02:32 PM (15 years, 8 months ago)

The type of fluid you describe is non-Newtonian; its behavior is characterized as pseudoplastic.  The shear stress decreases with an increasing rate of shear strain, so its viscosity lowers as it flows.  It seems strange, but they are not too mysterious.  The icing stuff sounds like a glycol or polyglycol. 

Ketchup is a common example of a (sort-of) pseudoplastic.  And you'd likely not learn much of this kind of thing in chemistry or physics (though more likely physics); it's fluid mechanics, which is more engineering-oriented.  It's especially key to both aerospace and chemical engineering.


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Edited by Minstrel (09/11/08 02:36 PM)

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OfflineMadtowntripper
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Re: Simple Chemistry/Physics Question [Re: Minstrel]
    #8912899 - 09/11/08 02:34 PM (15 years, 8 months ago)

That is precisely the succinct and informative reply I was looking for.

Thank you.


--------------------
After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action.  If you cannot throw it at least you can always drink out of it.  - Ernest Hemingway

If it is life that you feel you are missing I can tell you where to find it.  In the law courts, in business, in government.  There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent.    -Cormac MacCarthy

He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God.  - Aeschylus

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InvisibleMinstrel
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Re: Simple Chemistry/Physics Question [Re: Madtowntripper]
    #8912915 - 09/11/08 02:37 PM (15 years, 8 months ago)

*The shear stress decreases with the rate of shear strain.

Correction:  with an increasing rate of strain.  Whoops.  That's a key point.


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Offlineburitobomb
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Re: Simple Chemistry/Physics Question [Re: Madtowntripper]
    #8912926 - 09/11/08 02:39 PM (15 years, 8 months ago)

Propylene Glycol has ether in it i know this because i worked in a paint factory with chemicals galore once i spilled a full barrel of this stuff in the forklift runway it was terriable the stuff like stained the cement for more than a year it was a very slippery runway i bet you guys that spilled that shit had the biggest cheapest buzz of their life at the air port


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:mushroom2::mushroom2::smirk:

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OfflineMadtowntripper
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Re: Simple Chemistry/Physics Question [Re: buritobomb]
    #8912933 - 09/11/08 02:42 PM (15 years, 8 months ago)

It's really strange.  We use it at school too, it's what we use to cool down the rock saws.  And there you have to have on a respirator and full protective clothing and everything.

But at work, I'm usually soaked in it, down to my skin, all winter long.

I'll probably have cancer from it.


--------------------
After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action.  If you cannot throw it at least you can always drink out of it.  - Ernest Hemingway

If it is life that you feel you are missing I can tell you where to find it.  In the law courts, in business, in government.  There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent.    -Cormac MacCarthy

He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God.  - Aeschylus

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InvisibleMinstrel
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Re: Simple Chemistry/Physics Question [Re: buritobomb]
    #8912940 - 09/11/08 02:45 PM (15 years, 8 months ago)

Quote:

buritobomb said:
Propylene Glycol has ether in it i know this because i worked in a paint factory with chemicals galore once i spilled a full barrel of this stuff in the forklift runway it was terriable the stuff like stained the cement for more than a year it was a very slippery runway i bet you guys that spilled that shit had the biggest cheapest buzz of their life at the air port




Was the barrel old?  Was the stain a bleaching?  What colour was it?  If the stuff stained the cement, I'd be inclined to think the shit had formed peroxides.  Ether would not stain anything, nor likely glycol.  Nor is there any normal method by which propylene glycol would form ether.  If ether was in there, it was added by the manufacturer (was it very viscous?).  If there was indeed peroxides, you're fucking lucky the shit didn't explode on you.

Or the 'stain' might be because the floor was painted or coated or some shit.  Glycol/ether might solvate the coating and give the appearance of a stain.


--------------------

Edited by Minstrel (09/11/08 02:47 PM)

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Offlineburitobomb
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Re: Simple Chemistry/Physics Question [Re: Madtowntripper]
    #8912944 - 09/11/08 02:46 PM (15 years, 8 months ago)

i used to spill it on my self too i dont have any complications but ohsa says its very cancerous so who knows maybe will die sooner than u think for now just eat shrooms


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:mushroom2::mushroom2::smirk:

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OfflineMadtowntripper
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Re: Simple Chemistry/Physics Question [Re: Minstrel]
    #8912949 - 09/11/08 02:48 PM (15 years, 8 months ago)

Quote:

Minstrel said:
Quote:

buritobomb said:
Propylene Glycol has ether in it i know this because i worked in a paint factory with chemicals galore once i spilled a full barrel of this stuff in the forklift runway it was terriable the stuff like stained the cement for more than a year it was a very slippery runway i bet you guys that spilled that shit had the biggest cheapest buzz of their life at the air port




Was the barrel old?  Was the stain a bleaching?  What colour was it?  If the stuff stained the cement, I'd be inclined to think the shit had formed peroxides.  Ether would not stain anything, nor likely glycol.  Nor is there any normal method by which propylene glycol would form ether.  If ether was in there, it was added by the manufacturer (was it very viscous?).  If there was indeed peroxides, you're fucking lucky the shit didn't explode on you.




It does kind of sound like glycol.  It's ridiculously slippery and the stuff we use has very strong dyes in it.  The de-ice is fluorescent orange and the anti-ice is a deep green.  This helps us know what stage of the anti-ice regimen the crews are on.


--------------------
After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action.  If you cannot throw it at least you can always drink out of it.  - Ernest Hemingway

If it is life that you feel you are missing I can tell you where to find it.  In the law courts, in business, in government.  There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent.    -Cormac MacCarthy

He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God.  - Aeschylus

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InvisibleMinstrel
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Re: Simple Chemistry/Physics Question [Re: buritobomb]
    #8912950 - 09/11/08 02:48 PM (15 years, 8 months ago)

Quote:

buritobomb said:
i used to spill it on my self too i dont have any complications but ohsa says its very cancerous so who knows maybe will die sooner than u think for now just eat shrooms




MSDS says ohsa (is that ontario?) says it's wrong.  Health index is 0, means it's pretty safe.


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InvisibleMinstrel
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Re: Simple Chemistry/Physics Question [Re: Minstrel]
    #8912958 - 09/11/08 02:50 PM (15 years, 8 months ago)

Oh, if you are talking about dyed mixtures then.... some dyes can be pretty toxic, but it wouldn't be the glycol component being bad.


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Offlinezouden
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Re: Simple Chemistry/Physics Question [Re: johnm214]
    #8913156 - 09/11/08 03:42 PM (15 years, 8 months ago)

>I would guess the compound is some polymer that sticks to other molecules of itself.

Perhaps polyethylene glycol? Hmmm.


--------------------
I know... that just the smallest
                                                part of the world belongs to me
You know... I'm not a blind man
                                                    but truth is the hardest thing to see

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OfflineSeussA
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Re: Simple Chemistry/Physics Question [Re: Minstrel]
    #8913377 - 09/11/08 04:31 PM (15 years, 8 months ago)

> Health index is 0, means it's pretty safe.

Just don't drink it (if you are a cat)!  (For people, it really is pretty safe.)


--------------------
Just another spore in the wind.

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OfflinePhanTomCat
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Re: Simple Chemistry/Physics Question [Re: Seuss]
    #8914050 - 09/11/08 06:18 PM (15 years, 8 months ago)

***makes mental note***

:tongue:


>^;;^<


--------------------
I'll be your midnight French Fry....  :naughty:

"The most important things in life that are often ignored, are the things that one cannot see...."

>^;;^<

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Offlineburitobomb
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Re: Simple Chemistry/Physics Question [Re: PhanTomCat]
    #8914675 - 09/11/08 07:37 PM (15 years, 8 months ago)

fuck that get some in your fucking eye once!!!!!!!


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:mushroom2::mushroom2::smirk:

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