The high proportion of
carbon dioxide and the low proportion of oxygen in chimney gases makes a
mixture of acetylene and chimney gases non-explosive in any proportions,
and hence if the air is first wholly or to a large extent expelled from a
pipe, main, or apparatus, by means of chimney gases, acetylene may be
admitted, and a much shorter time allowed for the expulsion by it of the
contents of the pipe, before a light is applied at the burners, &c. This
plan, however, will usually only be adopted in the case of very large
pipes, &c.; but on a smaller scale the air may be swept out of a
distributing system by bringing it into connexion with a cylinder of
compressed or liquefied carbon dioxide, the pressure in which will drive
the gas to any spot where an outlet is provided. As these cylinders of
"carbonic acid" are in common employment for preparing aerated waters and
for "lifting" beer, &c., they are easy to hire and use.
TABLE (B).
Giving the Sizes of Pipe which should be used in practice for Acetylene
when the fall of pressure in the Pipe is not to exceed 0.1 inch. (Based
on Morel's formula.)
________________________________________________________
| | |
| Cubic Feet of | Diameters of Pipe to be used up to |
| Acetylene | the lengths indicated.
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