THE STORAGE OF GAS
o
Thus, if w = the weight of the top sheeting in Ib. per square foot.
and li = the gross pressure thrown by the holder then the efEective pressure will be—
(A — w) X area of beil — -7854 D2 (h —w) = P.
The net upward thrust on the dorne due to the gas will then be equal to -7854 D2 (Å—w), that is the effective pressure P. Then, referring to Fig. 398, it will be seen. that the resultant vertical thrust is kept in equilibrium by the tangential pull at the circumference acting at an inclina-tion DF or EF. In the triangle of forces FDO, if OF represents the net upward thrust of the gas, then DF represents in magnitude and direction the tangential pull in the plates.
OF = P,
in Ib. per square foot,
and
U II
FO
sin. FDO
FO sin. a
T1 , ,. - -i T P -7854 D*(Ä -w)
iheretore, tangential pull, i =—------ = —
sm. a
sin.a
Or, T, per foot léngth of circumference =
•7854 D2(A — w) sin.a
X
I -d
S a
I .S
CO
Q
II
per foot of circumference.
But (h — w) = effective pressure = P
DP 4 sin.a
T
This result is approximate, but any error is on the safe side. If the above, expression gives the pull per foot of circumference, then the total pull over the whoJe diameter
4 sin. a
and this thrust is taken by the two sections of the curb diametrically oppositc. Therefore, thrust on each section
»iÆxdÆ
\4 sm. a / 8 sm. a
Weight of the Side Sheets
This may be calculated by taking out the weight of the side sheeting, curbs, guide rollers, etc., from the specification or, more rea.dily, from a consideration of the above formula. The effective pressure thrown by the holder must necessarily be derived from the weight of the side sheeting, for owing to the upward thrust of the gas upon the dorne the weight of this portion is ineffektive. Considering Fig. 398, it will be seen, then, that the weight of the side sheets is represented by the vertical component of the tangential pull T ; moreover, the resultant of the two forces T