Surface area
It is the ratio of
the surface area of the reservoir to the change in volume in the tubing
that makes the WatrLevel so accurate.
As an example, if the WatrLevel staff is moved from position A to position
B (figure 1), a quantity of water will drain back into the reservoir.
This amount will be equal to the surface area of the water in the
tubing multiplied by point X minus point Y (which is the volume of water). See
figure 2.
figure 1
Since
the reservoir has a much greater surface area, the water is effectively
"dispersed" over the surface, the net effect is that the water
in the reservoir changes very little (figure 2).
For the exact calculations for the WatrLevel a48 click here.
For the exact calculations for the WatrLevel a24 click here.
It should be noted that when the WatrLevel is used in such a manner that
there is little change from point X to point Y (such as when checking
for level), the accuracy is nearly numerically perfect.
figure 2