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ETL 1110-9-10(FR)
5 Jan 91
d)
Calculate (A):
A
=
1759 sq ft + 1935 sq ft + 3894 sq ft
A
=
7588 sq ft
2)
Find the riser pipe area (AR) using equation 2-2:
AR = 2 B rR hR
(eq 2-2)
Where:
rR =
2.5 ft (Riser radius)
hR =
115 ft (Height of riser)
AR =
2 x 3.1416 x 2.5 ft x 115 ft
AR =
1806 sq ft
3)
Find the maximum design current for the tank bowl (IT)
using equation 1-1:
IT = (A) (I') (1.0 - CE)
Where:
A=
7588 sq ft (Total wetted area of
tankbowl from step 1 of paragraph
2-7b)
I' =
2/5 mA/sq ft (Required current
density from item 9 of paragraph
2-7a)
CE =
0.0 (Coating efficiency, wetted
inner surfaces will be uncoated,
from item 7 of paragraph 2-7a)
IT =
7588 sq ft x 2.5 mA/sq ft x (1.0 -
0.0).
IT =
18,970 mA; use 19.0 amp
4)
Find the maximum design
current
for
the
riser
(IR),using equation 1-1:)
IR = (AR) (I') (1.0 - CE)
Where:
AR =
1806 sq ft (Total surface area of
riser pipe from step 2 of paragraph
2-7b)
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