Re: Secondary form, New idea!!

[MShock8073-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

In a message dated 9/10/00 5:43:27 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

<< Hi Alex,
 
    Black PVC has a bad reputation especially when it is dull looking and
 leaves black marks on your hands (a sure sign of conductive carbon black).
 The outdoor and UV protected stuff is full of carbon black.  There is a
 black kind that is very shinny that seems to like high voltage, but best
 not to mess with black PVC unless you are sure. >>

I wonder if colored PVC, colored to help resist UV in outdoor applications, 
is being confused with ABS plastic pipe. Colored PVC is used for applications 
where either the whole system is PVC as in electrical conduit, or the system 
is partly white PVC and some portion needs to be sunlight resistant. This 
maintaining all PVC idea comes from the way the pipe is assembled. The 
chemical weld method is unforgiving of mixing different pipe types when the 
system is exposed to changing temperatures. The expansion rates of the 
different plastics can and sometimes will tear apart the weld. The ABS pipe 
seems to be common in manufactured homes and campers/motorhomes because it is 
more tolerant to freezing than PVC when filled with water. But, ABS is 
several times more expensive than PVC and this is why staying with PVC is a 
more popular choice in the construction trades. It can usually be found at 
places which deal with manufactured housing (Politically Correct speak for 
'trailers') But, some big home centers like Lowes sometimes carries a small 
selection.

How does ABS plastic perform as a coilform? It seems to be better at not 
absorbing moisture than PVC. But is it conductive? I don't have any scraps 
anymore since I outgrew making spud cannons or I would test it.

The easiest way to tell ABS from PVC, assuming you can't tell by looking or 
at least finding the label, is the way we did in my spud cannon building 
days.......cut off a ring of pipe about 2 inches long and try to smash it 
with a big hammer. The idea there was to see if the pipe was too brittle to 
use as a pressure vessel. But, I discovered, the PVC will almost always 
'shatter' and the ABS just seems to deform. That was important data when I 
was holding it in my hands while it contained enough pressure to propel a 
potato almost 300 yards but could also be used to tell the plastics apart 
very quickly for the purpose of scrounging coil parts.

Marc