A preliminary vacuum test ought to be conducted upon the condenser body,
and the exhaust piping between the condenser and turbine. To accomplish
this the circulating-water pipe D can be filled with water to the
condenser level. The relief valve should also be water-sealed. Any
existing leakage can thus be located and stopped.

Having made the condenser as tight as possible within practical limits,
vacuum might be again raised and, with the same parts sealed, allowed to
fall slowly for, say, ten minutes. A similar test over an equal period
may then be conducted with the relief valve not water-sealed. A
comparison of the times taken for an equal fall of vacuum in inches,
under the different conditions, during the above two tests, will reveal
the extent of the leakage taking place through the relief valve. It
seems superfluous to add that the fall of vacuum in both the foregoing
tests must not be accelerated in any way, but must be a result simply of
the slight inevitable leakage which is to be found in every system.

On a comparatively steady load, and with consequently only small
fluctuation in the volume of steam to be condensed, the conditions are
most favorable for regulating the amount of circulating water necessary.
Naturally, an excess of water above the required minimum will not affect
the pressure conditions inside the condenser. It does, however, increase
the quantity of water to be handled from the hot-well, and incidentally
lowers the temperature there, which, whether the feed-water pass through
economizers or otherwise, is not advisable from an economical
standpoint. Thus there is an economical minimum of circulating water to
be aimed at, and, as previously stated, it can best be arrived at by
running the turbine under normal load and adjusting the flow of the
circulating water by regulating the main valve and the tension upon the
spring T. Under abnormal conditions, the breakdown of an air pump, or
the sudden springing of a bad leak, for instance, the amount of
circulating water can be increased by a farther opening of the main
valve if necessary, and a relaxation of the spring tension by hand; or,
the spring tension might be automatically changed immediately upon the
vacuum falling.

The absolute freedom of all moving parts of the spraying mechanism
should be one of the tester's first assurances. To facilitate this, it
is customary to construct the parts, with the exception of the springs,
of brass or