MIL-HDBK-1004/10
The formula for a horizontally oriented anode is:
EQUATION:
R
=
0.0052 P/L x ln{[4L + 4L(S + L) ]/ds} + s/L - (s + L) -1
(10)
h
where
R
=
electrolyte-to-anode resistance for a single vertical
v
anode to a remote reference (ohms)
R
=
electrolyte-to-anode resistance for a single horizontal
h
anode to a remote reference (ohms)
P
=
electrolyte resistivity (ohms-cm) at the location and
depth of the anode
L
=
anode length or backfill column length if backfill is
used (feet)
d
=
effective diameter of anode or backfill column (feet)
s
=
twice depth of anode (feet)
Simplified Expressions for Common Situations. For many common
6.2.1.4
situations, the Dwight formulae have been simplified by combining terms and
eliminating terms that have insignificant values in most cases. Some of these
simplified formulae have been given in para. 4.2.6. In addition to these
simplified formulae, the following simplified formula is often used:
a)
Resistance of a Single Vertical Anode
EQUATION:
R
=
(P/L)K
(11)
v
where
R
=
electrolyte-to-anode resistance for a single vertical
v
anode to remote reference (ohms)
P
=
electrolyte resistivity (ohms-cm) at the location and
depth of the anode
L
=
anode length (feet) or backfill column length if backfill
is used
K
=
shape function from table below where:
L/d =
ratio of length-to-diameter of anode
K
L/d
K
L/d
1
0.008
16
0.0201
2
0.010
18
0.0207
3
0.012
20
0.0213
4
0.013
25
0.0224
5
0.0140
30
0.0234
6
0.0150
35
0.0242
7
0.0158
40
0.0249
8
0.0165
45
0.0255
9
0.0171
50
0.0261
10
0.0177
55
0.0266
12
0.0186
60
0.0270
14
0.0194
55
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