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Foam core PVC

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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Foam core PVC

Unread postAuthor: Just1ChanceFree » Mon Nov 16, 2009 8:35 pm

Anyone happen to know any pressure-specs about foam core pvc? If the anticipated burst pressure is high enough, it might still be safe for use in my application. I want to 3" pvc for my chamber, but the local store only seems to have the foam-core stuff. I only intend to run on about 30 psi of pressure, maybe up to 60 or 100 for tests if it's safe. Anyone know or done tests?

Also, I'm sure there's posts on this here by my searches failed: Where are good places to buy Schrader valves? hardware stores thus far have failed...
Thanks!
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Unread postAuthor: VH_man » Mon Nov 16, 2009 9:42 pm

would you pressurize a block of styrofoam to 30 PSI?

foam core (and cell core) is two paper thin layers of PVC with a Styrofoam like material in between. It is not safe for any pressure, really. The possibility of it rupturing is just far to great.

If it were me, I wouldn't even touch the stuff. Not even for a combustion.
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Unread postAuthor: Moonbogg » Mon Nov 16, 2009 9:46 pm

Cell core PVC is known to be too weak for spud guns and may fail. Cell core ABS is totally different and is very popular for use in combustion cannons.
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Unread postAuthor: Technician1002 » Mon Nov 16, 2009 10:28 pm

Moonbogg wrote:Cell core PVC is known to be too weak for spud guns and may fail. Cell core ABS is totally different and is very popular for use in combustion cannons.


Tooting my own horn, I personally tested the strength of ABS cellular core in one of my cannons. The results are here. I can say for certanty that ABS Cell Core Sched 40 pipe holds up to pressure quite well.

http://www.spudfiles.com/forums/abs-cellular-core-test-cannon-t17968.html
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Unread postAuthor: Moonbogg » Tue Nov 17, 2009 1:02 am

Just like getting the guys out of the Apollo 13 mess: Its not what it was designed to do, its what it CAN do that matters. Cell core ABS FTW.
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Unread postAuthor: benstern » Tue Nov 17, 2009 3:26 am

CELLCORE IS NOT SUITABLE FOR ANY TYPE OF PRESSURE BEARING VESSEL.

Geeze I thought we settled this back in 2005.
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Unread postAuthor: Technician1002 » Tue Nov 17, 2009 3:32 am

benstern wrote:CELLCORE IS NOT SUITABLE FOR ANY TYPE OF PRESSURE BEARING VESSEL.

Geeze I thought we settled this back in 2005.


You may be right, but my testing shows it is tougher than the average 2 Liter pop bottle. :D Maybe we should only allow soda pop to be shipped in approved pressure rated containers.. :twisted: :P
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Unread postAuthor: MrCrowley » Tue Nov 17, 2009 3:36 am

Well I think ABS cell core is alright for combustion assuming you thread everything (such as a meter) through double layers and don't have too many holes. SB15's cell core ABS advanced combustion cracked because of the holes in the chamber for meter and igniter IIRC.

I wouldn't even come close to recommending cell core PVC for an advanced combustion, even a basic combustion is pushing it. And I wouldn't use either cell core PVC or ABS in a pneumatic over 50 PSI (and I'd still cover it in towels and such at that pressure).

It's up to you, but I don't think anyway at Spudfiles would recommend the use of cell core PVC for any application because the safety risk is too great.
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Unread postAuthor: Technician1002 » Tue Nov 17, 2009 3:51 am

MrCrowley wrote:Well I think ABS cell core is alright for combustion assuming you thread everything (such as a meter) through double layers and don't have too many holes. SB15's cell core ABS advanced combustion cracked because of the holes in the chamber for meter and igniter IIRC.

I wouldn't even come close to recommending cell core PVC for an advanced combustion, even a basic combustion is pushing it. And I wouldn't use either cell core PVC or ABS in a pneumatic over 50 PSI (and I'd still cover it in towels and such at that pressure).

It's up to you, but I don't think anyway at Spudfiles would recommend the use of cell core PVC for any application because the safety risk is too great.


In the original post he was looking for something safe for use around 30 PSI. I run my cannon at 40-60 PSI in normal operation and this year's pressure test was at 85 PSI. That should give him plenty of safety margin to use the ABS Cellular Core pipe. As far as the safety risk, it seems to be lower than regular sched 40 PVC. See my thread on the test cannon. Safety is discussed. Also asked is if any testing was done. The answer is yes, testing has been done.
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Unread postAuthor: MrCrowley » Tue Nov 17, 2009 4:03 am

Did your test include such things as drilling holes in the chamber for a meter? I'd rather take pressure rated PVC to 100PSI over cell core ABS, but cell core ABS is probably better to be around than PVC when it fails.

SB15 was perfectly fine when his cannon 'failed', but had it been PVC, one could argue it would have never failed in the first place. But I do see the point you are making and under the right circumstances cell core ABS could be better than pressure rated PVC.
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Unread postAuthor: Technician1002 » Tue Nov 17, 2009 4:42 am

MrCrowley wrote:Did your test include such things as drilling holes in the chamber for a meter? I'd rather take pressure rated PVC to 100PSI over cell core ABS, but cell core ABS is probably better to be around than PVC when it fails.

SB15 was perfectly fine when his cannon 'failed', but had it been PVC, one could argue it would have never failed in the first place. But I do see the point you are making and under the right circumstances cell core ABS could be better than pressure rated PVC.


I did several things wrong. As part of the test the hole drilled for the air fill is in the side of the pipe, not through a double layer. (the test cannon is pneumatic) By accident, I got a fitting only part way in before it seized so it's not even properly seated in a coupler. It still passed testing. The construction flaws are in the test thread.
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Unread postAuthor: Moonbogg » Tue Nov 17, 2009 4:44 am

I don't see why more people don't use cell core ABS instead of pressure rated PVC. I myself have an advanced combustion ABS cannon and have had a lot of use out of it without incident. ABS is MUCH lighter than PVC and has better failure characteristics. Those atributes alone I think have a lot of merit. When you get into pneumatics thats a different story of course (I think).
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Unread postAuthor: MrCrowley » Tue Nov 17, 2009 4:56 am

Well to be fair, has anyone heard of a PVC pressure rated advanced combustion built correctly failing because of something to do with the PVC?

Though moonbogg brings up a good point with weight and failure characteristics. Other factors are cost and tempreature and shock-resistant values of ABS.
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Unread postAuthor: Technician1002 » Tue Nov 17, 2009 9:45 am

MrCrowley wrote:Well to be fair, has anyone heard of a PVC pressure rated advanced combustion built correctly failing because of something to do with the PVC?

Though moonbogg brings up a good point with weight and failure characteristics. Other factors are cost and tempreature and shock-resistant values of ABS.


Add chemical resistance. As DWV, the stuff is resistant to many chemicals. This is good for spray N pray where most anything may be sprayed in there.
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Unread postAuthor: grock » Fri Nov 20, 2009 2:04 am

since the first part was answered pretty well, try the internet for schrader valves, http://www.mcmaster.com is a good site
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