Snail Scott on thu 7 dec 00
At 11:53 AM 12/7/00 -0700, you wrote:
If the vessel
>leaks, the pressure inside propagates the rupture and the vessel splits,
>sometimes into flying pieces of shrapnel. An example is the dangerous use
>of rigid plastic pipe some folks hook up to compressed air. When rigid
>plastic pipe breaks with air pressure inside, it can shatter and hard
>plastic shrapnel flies all over. That can have fatal consequences!
> Dave Finkelnburg
I can confirm this! A shop I worked in had steel air
lines running from the high-pressure industrial
compressor, but the addition to the building had been
connected with PVC. One day, without warning, a section
of the pipe exploded, sending shards of PVC through the
walls and roof, missing me by inches. Workman's Comp
would not have helped my severed head much, I suspect!
Use air with respect - the kind you breathe, and the
kind you pressurize!
-Snail
Dave Finkelnburg on thu 7 dec 00
Hi All!
David Hendley's low-tech safety relief is certainly a relief to me! :-)
When I read that he was using a water tank for an air receiver, I really
cringed. Air receivers with commercial compressors are designed, by law in
the U.S., to American Society of Mechanical Engineers (ASME) code because
compressed air or any other vapor under pressure, is so deadly if the
container it's in ruptures.
Water in a pressure vessel isn't so dangerous, unless the quantity of
water can drown one. Water, in fact, is used to test pressure vessels,
because if the vessel leaks, the pressure immediately drops and maybe
someone gets wet. Air or steam or other vapor is different. If the vessel
leaks, the pressure inside propagates the rupture and the vessel splits,
sometimes into flying pieces of shrapnel. An example is the dangerous use
of rigid plastic pipe some folks hook up to compressed air. When rigid
plastic pipe breaks with air pressure inside, it can shatter and hard
plastic shrapnel flies all over. That can have fatal consequences!
Relief valves are great, but they are mechanical devices which will fail
eventually. David's low-tech approach of using a soft hose is intelligent.
Yours for safe potting!
Dave Finkelnburg
Idaho Fire Pottery
David Hendley wrote:
>I should have mentioned the 'pop off' valve designed
>into the East Texas Special air compressor.
>There's no worry about a tank rupture on this model, as the
>rubber hose from the compressor to the tank will 'pop off'
>the compressor outlet tubing long before there is any danger.
>My set-up won't go over 120 p.s.i., way lower than any
>pop-off valve, but, of course, you should keep this in mind
>should you start tinkering with high air (or water) pressure.
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