THE STORAGE OF GAS 677
In the couT.se of his examination of dams and river walls, Baker found that in some cases it was possible to thrust down an iron bar some considerable distance between the earth and the brickwork, showing that the latter was receiving practically no assistance from the earth backing. Such conditions might well be found in the case of semi-buried tanks having the earth mounded up against the tipper portion. In such instances there may be some tendency for the earth to slide backwards and so relieve the pressure against the wall.
An old-fashioned rule, due to Wyatt, for the proportion of brick tanks, is as follows :—
Thickness of concrete walls = t-q the depth of tank
„ „ piers
Width „ piers
This refers to tanks up to
For very large holders, firm foundation, free from and ballast at reason-able prices, are cheaper than the brick variety, and they are in almost all cases rendered on the inferior. The brick tank possesses advantages over the concrete tank in that less skili is required in its construction, tliere
_ 1
_ 1
— 7 ” ” ’> ”
150 feet diameter and 36 feet deep.
a brick or concrete tank is most suitable water, can be obtained. Concrete tanks,
, so long as a with cement-
is less initial stress due to shrinkage, and less liability towards Cracking caused by any variation in the temperature of the water. The method of con-necting up inlet and outlet pipe to a gas-holder with masonry tank and the construc-tion of the “dry well ” is shown in Fig. 417. In Fig. 419 is shown a method sometimes
Fig. 420.—Common Form of Dky Well.
adopted on the Continent. It will be noted that the inlet and outlet pipes, instead of being supported with iron stays, are jacketed with brickwork or concrete. Au en-larged view of a common form of dry well is shown in Fig. 420.