(1) However, the L/d ratio of two 1-1/2-inch diameter by
60-inch long anodes in tandem is less than 100 and thus the fringe factor
must be used.
L/d = (2 x 60)/1.5
L/d = 80 < 100
(2) The fringe factor from curve Figure 101 corresponding to
L/d ratio is 0.95.
R (adjusted) = 3.19 x 0.95
R = 3.03 ohms
(1) In the design of an elevated water tank, the need for stu
anodes must be justified. The main anode radius has been calculated to b
22 feet. The main anodes are spaced to provide approximately the same
distance from the sides and the bottom of the tank. The main anodes will
protect a length along the tank bottom equal to 1-1/2 times the spacing o
the anode from the bottom.
(2) The anode suspension arrangement for the tank under
consideration is shown in Figure 99. Thus, it can be seen that stub anod
are required for this design. Ten stub anodes are arranged equally space
on a circumference that has a radius of 8 feet in a manner illustrated in
Figure 98. For smaller diameter tanks, stub anodes may not be required.