pvc pressure pot

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OLLIEwinz

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Mar 1, 2016
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nottigham england
i wanted to start casting alumalite but can't really afford a pressure pot, i thought about making one from 6'' pvc with a flat endcap one one end with a gauge, a 50 psi safety valve, and on the front,a screw on cap with a ball valve with a compressor fitting. the pvc would have a tray inside for molds.any ideas thoughts concerns?
 
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Monty

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Plus the flat 4" and larger PVC caps are for DWV and not pressure rated. It's the rounded caps that are used for pressure.
 

cal91666

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Jul 10, 2013
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Richmond, VA
As stated above ....... DON"T DO IT!!!!! Do a goggle search for compressed air in PVC pipe. You will find a lot of horror stories, OSHA warnings, as well as PVC pipe manufacturers warnings against using PVC pipe for compressed air or gases.
 

thepenguy

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Mar 26, 2016
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Finleyville PA
Not all PVC is created equal. their is foam core and solid. foam core is not to be used for pressure and is marked as such but solid is rated for pressure. on the side of the pipe its stamped with the rating. for example I looked at 1" solid PVC I had and its rated for 480 psi @ 73 degrees. all the horror stories are used with foam core or exceeding it rating.
 

jttheclockman

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Take a step back for a minute. How far along the pen turning journey are you??? If you can not afford a pressure tank then try using cast-n-craft or Silmar resin for casting instead of aluminite and you do not need pressure. There are pluses and minuses with both. It is a cheaper way to cast.

As warned do not jury rig something like that. It is not worth the risk at all.
 

cal91666

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Your link leads to a document that references ASTM D1785 as the standard used for the chart. ASTM D1785 clearly states ... This specification covers poly(vinyl chloride) (PVC) plastic pipe, schedules 40, 80, and 120 for use with the distribution of pressurized liquids only
 

thepenguy

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what Is dangerous is pvc is very brittle material that can be broken or shattered with external force unless properly protected. Compressed gasses can be best described as being analogous to a coiled spring. When a PVC pipe or fitting fails when under stress from compressed gas it literally explodes like a bomb, sending shards of plastic flying several feet in all directions. Liquids, on the other hand, being compressed by only 1/10th of 1% contain very little stored energy. When pressurized systems with liquids fail, the energy is dissipated very quickly, thereby creating a much lower potential for hazard. So the question is not can it handle the job. yes it can but if you are around when it fails you may me seriously injured. thousand of air pressure systems have been installed and work fine but it only takes a few accidents to get the attention of OSHA to make the manufactures change their recommendations. let me end this dicshion with this. This topic I happen to to be very intimat with but the use of pvc for air pressure can be done and done safely. Especially the sch 80 and 120. But with that all said go out and buy a pressure chamber and use it the way it wan intended.
 
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