MIL-HDBK-1004/10
where
Y
=
10 years
S
=
1.0 lbs/A yr
E
=
0.50
I
=
15.2 A
W
=
10 x 1.0 x 15.2/0.50 lb
W
=
304 pounds
f)
Minimum weight of riser anode material:
W
=
YSI/E
where
Y
=
10 years
S
=
1.0 lbs/A yr
I
=
3.62 A
E
=
0.50
W
=
10 x 1.0 x 3.62/0.50 lb
W
=
72.4 lb
g)
Radius of main anode circle:
= (DN)/2(B+N)
r
where
D
=
56 feet
N
=
10 (assumed number of anodes)
r
=
56 x 10/2(3.1416 + 10)
r
=
560/26.28
r
=
21.3 feet, use 22 feet
h) Spacing of main anodes. Generally the distance from the anode
to the tank wall and tank bottom is about equal; this distance should be about
one-half the circumferential distance between anodes.
(1)
Circumferential spacing:
= (2Br)/N
C
where
r
=
22 feet (radius of anode circle)
N
=
10 (assumed number of anodes)
C
=
2 x 3.1416 x 22/10
C
=
13.8 feet, use 14 feet
(2) Cord spacing is approximately the same as circumferential
spacing:
14 feet will be used (see Figure 98).
159
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