04, then
(1) (_v_/_v'_) = (0.40 / 0.91)^(1/2) = 0.663
or, _v_ = 0.663_v'_,
which signifies that the loss of acetylene by leakage under the same
conditions of pressure, &c., will be only 0.663 times that of the loss of
coal-gas. In practice, however, the pressures at which the gases are
usually sent through mains are not identical, being greater in the case
of acetylene than in that of coal-gas. Formula (1) therefore requires
correction whenever the pressures are different, and calling the pressure
at which the acetylene exists in the main _p_, and the corresponding
pressure of the coal-gas _p'_, the relative losses by leakage are--
(2) (_v_/_v'_) = (0.40 / 0.91)^(1/2) x (_p_/_p'_)^(1/2)
_v_ = 0.663_v'_ x (_p_/_p'_)^(1/2)
It will be evident that whenever the value of the fraction
(_p_/_p'_)^(1/2), is less than 1.5, _i.e._, whenever the pressure of
the acetylene does not exceed double that of the coal-gas present in
pipes of given porosity or unsoundness, the loss of acetylene will be
less than that of coal-gas. This is important, especially in the case of
large village acetylene installations, where after a time it would be
impossible to avoid some imperfect joints, fractured pipes, &c.
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