the losses due to setting deterioration,
resulting from such lack of suction. Under conditions where the suction
is not sufficient to carry off the products of combustion, the action of
the heat on the setting brickwork will cause its rapid failure.

[Illustration: 7800 Horse-power Installation of Babcock & Wilcox
Boilers, Equipped with Babcock & Wilcox Chain Grate Stokers at the
Metropolitan West Side Elevated Ry. Co., Chicago, Ill.]

It becomes evident, therefore, that the question of stack height for
oil-fired boilers is one which must be considered with the greatest of
care. The designer, on the one hand, must guard against the evils of
excessive draft with the view to plant economy, and, on the other,
against the evils of lack of draft from the viewpoint of upkeep cost.
Stacks for this work should be proportioned to give ample draft for the
maximum overload that a plant will be called upon to carry, all
conditions of overload carefully considered. At the same time, where
this maximum overload is figured liberally enough to insure a draft
suction within the setting under all conditions, care must be taken
against the installation of a stack which would give more than this
maximum draft.

TABLE 56

STACK SIZES FOR OIL FUEL

ADAPTED FROM C. R. WEYMOUTH'S TABLE (TRANS.
A. S. M. E. VOL. 34)

+----------------------------------------------------+
|+--------+-----------------------------------------+|
|| | Height in Feet Above Boiler Room Floor ||
||Diameter+------+------+------+-----+--------------+|
|| Inches | 80 | 90 | 100 | 120 | 140 | 160 ||
|+--------+------+------+------+------+------+------+|
|| 33 | 161 | 206 | 233 | 270 | 306 | 315 ||
|| 36 | 208 | 253 | 295 | 331 | 363 | 387 ||
|| 39 | 251 | 303 | 343 | 399 | 488 | 467 ||
|| 42 | 295 | 359 | 403 | 474 | 521 | 557 ||
|| 48 | 399 | 486 | 551 | 645 | 713 | 760 ||
|| 54 | 519 | 634 | 720 | 847 | 933 | 1000 ||
|| 60 | 657 | 800 | 913 | 1073 | 1193 | 1280 ||
|| 66 | 813 | 993 | 1133 | 1333 | 1480 | 1593 ||
|| 72 | 980 | 1206 | 1373 | 1620 | 1807 | 1940 ||
|| 84 | 1373 | 1587 | 1933 | 2293 | 2560 | 2767 ||
|| 96 | 1833 | 2260 | 2587 | 3087 | 3453 | 3740 ||
|| 108 | 2367 | 2920 | 3347 | 4000 | 4483 | 4867 ||
|| 120 | 3060 | 3660 | 4207 | 5040 | 5660 | 6160 ||
|+--------+------+------+-----