PVC Pipe Gasoline Resistance Test

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Postby plasticex009 » Mon Jan 03, 2005 3:21 am

Here are the results from my test on the resistance of PVC pipe to gasoline.

<b>Materials:</b>

-3 sections of 3/4" SCH40 pressure rated PVC pipe
-Gasoline (87 octane)
-Sunnyside laquer thinner (Contanes: Toulene, Acetone, Ethyl Acetate, Isopropyl Alcohol, Alcohol, and Petroleum Distillates)
-Two solvent resistant containers with lids


<b>Procedure:</b>

- Two sections of PVC pipe were placed in seprate containers and submerged in the above solvents for ~54 hours with temperatures ranging from 30-45F.
- The sections were removed from the solvents, wiped clean, and their wall thicknesses and outer diameters were measured.
- The sections were placed under a heavy weight (30lb steel bar) and photographed to show how much they had softened.


<b>Results:</b>

<img src="http://home.mchsi.com/~hanson49/PVCGRT/001.jpg">

1] Unsoaked 2] Gasoline and 3] Lacquer thinner

<i>-Dimensions</i>
<pre>Pipe section Max Outer Diameter(mm) Max Wall Thickness(mm)
1) Unsoaked 21.5 2.9
2) Gasoline 21.5 2.9
3) Lacquer Thinner 22.8 4.2
</pre>
<i>-Smell</i>

1) Normal PVC smell
2) Normal PVC smell with a hint of gasoline (gasoline smell disappeared after ~1 hour out of the solvent)
3) Strong lacquer thinner smell

<i>-Softness</i>

Here a ~30lb steel bar was used to crush the pipe sections to demonstrate how soft/hard they were after soaking in the solvents. I will let the photos speak for themselves.

<img src="http://home.mchsi.com/~hanson49/PVCGRT/002_U.jpg">
Normal pipe section

<img src="http://home.mchsi.com/~hanson49/PVCGRT/002_G.jpg">
Gasoline soaked pipe section

<img src="http://home.mchsi.com/~hanson49/PVCGRT/002_A.jpg">
Lacquer thinner soaked pipe section

<i>Other Photos</i>

gasoline (left), lacquer thinner (middle), normal (right)

<img src="http://home.mchsi.com/~hanson49/PVCGRT/003_01.jpg">


<img src="http://home.mchsi.com/~hanson49/PVCGRT/003_02.jpg">

<img src="http://home.mchsi.com/~hanson49/PVCGRT/003_03.jpg">
Unsoaked (left), Gasoline (middle), Laquer Thinner (right)

<b>Conclusion</b>

The pipe section soaked in gasoline shows no signs of gasoline penetration or deterioration. The fact that the gasoline smell dissipated from the plastic leaves me to think the solvent didn't penetrate the plastic.

The section soaked in lacquer thinner clearly shows signs of solvent penetration. The deterioration of this pipe segment was expected because lacquer thinner contains Toulene and Acetone, which are known to soften PVC plastic. The segment enlarged to 145% the wall thickness and 106% of the unsoaked pipe section's outer diameter. The lacquer thinner soaked pipe section was cut open revealing the solvent had penetrated completely through the plastic material.

Both solvents remained the same color/clarity throughout the test, which means the PVC plastic didn't dissolve; the solvent only penetrated into one of the pipe sections.

I think it is safe to say that PVC is highly resistant to gasoline penetration and no adverse effects will result from gasoline contacting PVC pipe.

Edit - Format correction
Edit 2 - Clarification and additions
Edit 3 - I switched hosts so there should be fewer problems with the photos displaying.
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Postby Mr.Plow » Mon Jan 03, 2005 3:38 am

Thanks for the test! Well done indeed. Finally we have rock solid proof that gas does not cause PVC to deteriorate.

One quick question: can we be sure that just the bar test is adequate for testing the pipe's strength? Would the stresses of pressurization be similar enough? I ask this because I've got several sections of pipe that I wouldn't use ever for a chamber (they've been knocked around a lot, probably full of imperceptible cracks that would cause a failure during pressurization). Even though I don't trust em to hold up if I charged em to 100psi, they are solid enough. Can you tell if the gas-soaked pipe is more brittle?
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Postby plasticex009 » Mon Jan 03, 2005 4:23 am

The bar test was merely to show in the photographs that the gasoline soaked pipe segment was not soft like the one soaked in lacquer thinner. It wasn't intended to test the pressure handeling capabilities of the pipe.

The gasoline soaked segment is "identical" in surface texture, hardness, and size to the unsoaked pipe segment, so I believe there was no chemcal/physical change in the pipe. Therefore the pressure handeling capabilities would not have changed.

When dropped onto a hard surface, the gasoline soaked segment sounds exactly like the unsoaked segment, while the lacquer thinner segment makes a thud sound (like rubber).
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Postby Mr.Plow » Mon Jan 03, 2005 5:08 am

Ok then, I understand. Sorry for any confusion:(.
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Postby OJHSPyro89 » Mon Jan 03, 2005 4:23 pm

Im glad smart people like you prove people wrong the right way!!!!

Well done, and again you impress me with your ability to actually perform good experiments.

Wanna do my science fair!? lol
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Postby PCGUY » Mon Jan 03, 2005 5:10 pm

This question comes up a lot... stickied for now..
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Postby PotatoNick » Fri Jan 07, 2005 8:52 pm

so... what your saying is that it is safe, will not blow me or anything else attached to me up, to use gas in your potato gun? (i'm not trying to sound sarcastic) It will give a good combustion wont it?
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Postby Mr.Plow » Fri Jan 07, 2005 9:04 pm

"I think it is safe to say that PVC is highly resistant to gasoline penetration and no adverse effects will result from gasoline contacting PVC pipe." -Plasticex

Still, I don't like to use it because it has a noxious smell, plus it is a very flammable liquid. If you accidently get some on your hands or clothes, and a spark from the cannon gets too close...well, skin grafts suck. I don't think its a very good fuel anyways. For your money, you'd be much better off just buying a cylinder of propane. Its totally not worth the risk
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Postby plasticex009 » Sat Jan 08, 2005 2:41 am

This topic is not about fuel meters. It has been edited accordingly.
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Postby plasticex009 » Sat Jan 08, 2005 3:28 am

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">so... what your saying is that it is safe, will not blow me or anything else attached to me up, to use gas in your potato gun? (i'm not trying to sound sarcastic) It will give a good combustion wont it?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

This topic is about the chemical resistance of PVC pipe. Not about if your launcher will blow up. Chances are if gasoline is used as a fuel, the launcher will not "blow up." Yes, gasoline is combustible.

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Its totally not worth the risk<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I am sure that is exactly what those who used hairspray said when a few people started using propane. ;) The ammount of gasoline needed to fuel a launcher would be in the order of a few drops. I wouldn't call that a fire hazzard. For a days worth of shooting using a 3L chamber launcher, one could easily use under 50 mL of gasoline (I did the calculations). That is about the volume of a film canister.

To use propane reliably, one needs a fuel meter, plumbing, and a fuel canister; costing +$50 for all.

To use gasoline reliably, one needs a volumetric measuring tool (syringe) and probably a chamber fan (under $30). Vaporization would happen quickly in a chamber with a fan.
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