Re: Inner tubes - Failure pictures vent holes

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Gary Weaver" <gary350-at-earthlink-dot-net> 

About 20 years ago I use to install expandable foam in the walls of houses.
We use to drill several vent holes in the walls then inject the foam in one
hole at the bottom of the wall.  The foam would expand and squirt out all
the vent holes.  As the foam expanded you could see how far up the wall it
had expanded by watching it squirt out each vent hole one at a time.  If the
foam did not come out all of the vent holes we would inject a little more
near the top.  90% of the expansion was done in the first 30 seconds.
Another 8% of the expansion was done in the next 10 minutes or so.  The last
2% of the expansion was done over then next few hours.  Without the vent
holes the foam would push the sheet rock off the walls.

Maybe you need some vent holes in your project.

Gary Weaver




----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, December 28, 2003 5:38 PM
Subject: RE: Inner tubes - Failure pictures


 > Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com>
 >
 > Hi Chris:
 >
 > Thanks for the details.
 >
 > The polyurethane foam that I experimented with is cured by the presence
 > of water vapor.  I added a small spoonful of water to the inside of my
 > corrugated aluminum duct toroid and shook it about before filling with
 > foam.  I had no trouble with the foam curing to a very solid state, but
 > it was impossible to blindly judge when to stop adding foam with the
 > solid form.  An initially-deflated inner tube may provide a better
 > indication of filling status.
 >
 > My duct toroid burst its taped-shut seam several hours after filling, so
 > it's probable that some improvement over a zero-pressure size is
 > possible.  But the degree to which this occurs and the uniformity of
 > expansion are questionable.
 >
 > Regards, Gary Lau
 > MA, USA
 >
 >
 > Original poster: C T <ct451-at-yahoo-dot-com>
 >
 > I made 12 1/4" cuts on the tube but my guess is that lot
 > more are needed. The tube, except from the part where
 > the label is, does look filled up without any voids. The
 > density of the foam inside is very low. It feels like a sponge
 > when you press on it.
 > This is a step up from my first attempt with a tube
 > with no vents. The foam that time was as if it was still in
 > the can, took forever to solidify and when I removed the can
 > all the air came out.
 > More holes could be the answer although I'm afraid the
 > Foam may not be strong enough to expand the tube to a
 > diameter of 3+ inches.
 >
 > The specs for the coating I mentioned are at
 > http://www.cramolin.de/lackeen.htm#emilac
 >
 > Thanks again,
 > Chris
 >  >  >  >Original poster: "C.T." <ct451-at-yahoo-dot-com>
 >   >  >  >
 >   >  >  >When good foam goes bad:
 >   >  >  >
 >   >  >  >http://www.geocities-dot-com/ct451/toroidart.html
 >   >  >  >
 >   >  >  >I'm thinking of using it after coating it with
 >   > EMV-LACK from cramolin.
 >   >  > Is
 >   >  >  >it conductive enough to work on a top load?
 >   >  >  >
 >   >  >  >Thanks
 >   >  >  >
 >   >  >  >Chris
 >   >  >
 >   >  >
 >   >
 >
 >