Fig.B-10 Binary (two-position) fluidic indicator
of state in manufactured by Norgren, United Kingdom:
Diaphragm deformation due to hydrostatic pressure admitted
into input X is transformed by the crank mechanism into rotation
of the sphere, the alternatively visible halfs of which are diffe-
rently painted. Used on a panel, dimensions equivalent to
those of a light-bulb electric indicator.

Fig.B-11


















(flow rate on fluidic side, mechanical motion velocity on the mechanical side) and vice versa. The limitation to alternating flow in the fluidic side may be circumvented by using one-direction valves.

Fig.B-12


- caused by hydrostatic pressure of liquid in a vessel:
A typical problem the solution of which is handled in this paragraph is calculation of the stress in bolts (or number of bolts) which hold some cover that covers an opening in the vessel wall. It is assumed that there is the barometric pressure acting on the liquid surface (- this means pressure vessels are not considered) as well as on the outer face of the cover. In Fig.B-12 there is a derivation of the elementary force on an infinitesimally small wall (cover) surface element. The effects of from the both sides cancel each other so that the elementary force depends only upon the height of liquid layer between the investigated area element and the level surface above. The resultant force effect is then obtained by integration over the whole part

Fig.B-13
of the vessel wall, as represented in Fig.B-13. Since both and are constant, their ratio may be extracted in front of the integral.
1) The case of horizontal plane wall
The simplest case of this integration, of course, is encountered if the wall - the force on which is to be calculated - is a horizontal bottom (Fig.B-14). In this case the height difference is the same for any wall element, so that it is possible to extract in front of the integral also this quantity.

Obr.B-14








The result, shown in Fig.B-14, may be under some circumstances also interpreted as the force being equal to the weight of liquid poured into the vessel. This



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This is page Nr. B05 from textbook Vaclav TESAR : "BASIC FLUID MECHANICS"
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