system, and before a test to
insure that these valves are all set to open at their correct relative
pressures.

It must be admitted that the practice of placing a large relief valve
upon a condenser in addition to the atmospheric exhausting valve is by
no means common. The latter valve, where surface condensing is adopted,
is often thought sufficient, working in conjunction with a quickly
operated main exhaust valve. Similarly, with a barometric condenser as
that illustrated in Fig. 72, the atmospheric exhaust valve D (seen in
Fig. 73) is sometimes dispensed with. This course is, however,
objectionable, for upon a loss of vacuum in the turbine, all exhaust
steam must pass through the condenser body, or the entire plant be
closed down until the vacuum is regained. The simple construction of the
barometric condenser, however, is in such an event much to its
advantage, and the passage of the hot steam right through it is not
likely to seriously warp or strain any of its parts, as might probably
happen in the case of a surface condenser.

The question of the advisability of thus adding to a plant can only be
fairly decided when all conditions, operating and otherwise, are fully
known. For example, if we assume a large turbine to be operating on a
greatly varying load, and exhausting into a condenser, as that in Fig.
72, and, further, having an adequate stand-by to back it up, one's
obvious recommendation would be to equip the installation with both a
condenser relief valve and an atmospheric valve, in addition, of course,
to the main exhaust valve, which is always placed between the
atmospheric valve and condenser. There are still other considerations,
such as water supply, condition of circulating water, style of pump,
etc., which must all necessarily have an obvious bearing upon the
settlement of this question; so that generalization is somewhat out of
place, the final design in all cases depending solely upon general
principles and local conditions.

Other Necessary Features of a Test

In connection with the condenser, of any type, and its auxiliaries,
there remain a few necessary examinations and operations to be
conducted, if it is desired to obtain the very best results during the
test. It will be sufficient to just outline them, the method of
procedure being well known, and the requirement of any strict routine
being unnecessary. These include:

(1) A thorough examination of the air-pump, and, if possible, an