St. Landry clarion. (Opelousas, La.) 1890-1921, 1899-04-29
pER1Ls OF COMPRESSED AIR.
Properly Bottled, 1t May Be Used In
Prope1Hing Cars with Lit
tie Danger.

Until recently experiments in the line
of pneumatic traction were confined to |
air at moderate pressures, mainly be- |
cause safe bottle or receiver was not |
available. In designing a vessel in
which to store the air it is necessary to |
consider the question of weight, and as
the air pressure was increased the |
weight of common receivers became so
great as to be prohibitiye. During re-
cent years there has been imported q |
weldless, cold-drawn steel tube which |
has served the purpose very well. This
tube is known as the Mannesman bot |
tie, and is made in Germany. It's safety
lies in the fact that it is drawn from
solid billet of steel, hollow throughout,
with rounded ends, forming a vessel OF
uniform strength and with no joints or
YIELDS of any kind. One end of the
Mannesman bottle is tapped for pipe
of small diameter which connects with
the interior and which serves as an out
let or inlet for the compressed air.
This form of bottle is safe vessel for
air at pressure of 1000 pounds per
square inch, and it is SO designed that
a number of these bottles, each about
| the length of the space under the seats
of street car are laid side by side and
connected at one end, thus storing
enough air, as in the case of the Hardie
car, to run approximately 25 miles.
Some experiments have been made
| with cold-drawn bottles made of nickel
steel, which it is claimed will store air
at 5000 pounds pressure per square
inch, and as the tensile strength of
nickel steel is high, bottles made of this
| material should be able to safely carry
| large volumes of compressed air in
/ small space and without the handicap
4 of serious weight. Now the safety of
steel bottle carrying compressed air is
a simple question of engineering. The
air bottle is practically at all times sub
| iect to uniform temperature. It is
/ designed to stand certain pressure,
and if, properly tested before use and
factor of safety established beyond its
| working strains there remains but lit
tie uncertainty or danger in its use.
Nothing in engineering is safe to
| point of certainty, but it can safely be
claimed that in the steel bottle the ele-
ments of uncertainty are small and
easily controlled; that the botIles are
not subject to deteriorating influences.
as they are surrounded by free air on
the outside and compressed air on the
inside; that when made properly and
carefully tested they may safely be
used to carry air pressure strains of
one-half the figures at which they are
tested, and as it is quite possible to
provide these vessels with blow-off
valves they may be made practically
safe.
Even though an air bottle should
explode when carrying air at pressures
of several thousand pounds to the
square inch, it is not likely to be as de-
structive as is usually supposed. These
bottles are arranged in series, which is
; in some respects like the water tube
boiler, which is considered to be the
safest form Of boiler made. Water tube
boilers do not explode. There have
been instances where one or more OF
the tubes have been disrupted, but the
: effect is only local, while with common
cylindrical boilers, explosions have
been frequent, and the results serious
Air when released shrinks rapidly in
volume, because of rapid lowering OF
Temperature This tends to reduce tho
force of explosion. The effect would
very likely be local and Of very short
duration. as the air once released if
soon discharged. d.-Compresse Air.