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ETL 1110-9-10(FR)
5 Jan 91
IA =
Allowable amp per ft of anode wire
(varies
depending
on desired anode
life and diameter), found in table A-
3.
Based on
selecting a wire anode of
0.0625-in.
diameter, the minimum wire length and hoop diameter
can be calculated:
For 0.0625 in. LB
=
12 amp
0.31 amp/ft
=
38.7 ft
12 ft 4 in
(Length of
(Minimum
Wire for
Diameter of
15-Year Life)
Wire Circle)
4)
Calculate the desired diameter of the anode wire
circle (DR). Experience shows that the diameter of
the anode wire circle should be between 40 and 70
percent of the tank diameter for a cylindrical tank.
In this case, we will try a hoop shape with a diameter
equal to 60 percent of the bowl diameter:
DR = 60% x 46 ft = 27.6 ft; use 27 ft 6 in
5)
from equation 1-14:
8 DR
2 DR
0.0016 p
RA '
% 1n
(1n
DR
DA
H
Where:
p =
2000 ohm-cm (Water resistivity from
item 2 of paragraph 2-8a)
DR =
27.5 ft (Anode ring diameter from
previous calculation)
DA =
Assume
0.0052
ft
(0.0625
in)
(Diameter of anode wire from step 3
of paragraph 2-8b)
107
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