esents the loss of head in feet, then

f 2 v*v W L
E_{f} = Wh = ----------- (39)
gd

f 2 v*v L
and h = --------- (40)
gd

If D represents the density of the steam or weight per cubic foot, and p
the loss of pressure due to friction in pounds per square inch, then

hD
p = --- (41)
144

and from equations (38), (40) and (41),

D v*v L / 3 \
p = --------- x K | 1 + --- | (42)
72 g d \ 10d /

To convert the velocity term and to reduce to units ordinarily used, let
d_{1} the diameter of pipe in inches = 12d, and w = the flow in pounds
per minute; then

[pi] / d_{1}\
w = 60v x --- | ---- |^{2} D
4 \ 12 /

9.6 w
and v = --------------
[pi] d_{1}^2 D

Substituting this value and that of d in formula (42)

/ 3.6 \ w^{2} L
p = 0.04839 K | 1 + ----- | ----------- (43)
\ d_{1} / D d_{1}^{5}

Some of the experimental determinations for the value of K are:
K = .005 for water (Unwin).
K = .005 for air (Arson).
K = .0028 for air (St. Gothard tunnel experiments).
K = .0026 for steam (Carpenter at Oriskany).
K = .0027 for steam (G. H. Babcock).

The value .0027 is apparently the most nearly correct, and substituting
in formula (43) gives,

/ 3.6 \ w^{2} L
p = 0.000131 | 1 + ---- | ----------- (44)
\ d_{1}/ D d_{1}^{5}

/ pDd_{1}^{5} \
w = 87 | -------------- |^{.5} (45)
| / 3.6 \ |
| | 1 + ---- | L |
\ \ d_{1}/ /

Where w = the weight of steam passing in pounds per minute,
p = the difference in pressure between the two ends of the pipe in
pounds per square inch,
D = density of steam or weight per cubic foot,[80]
d_{1} = internal diameter of pipe in inches,
L = length of pipe in feet.

TABLE 66

FLOW OF STEAM THROUGH PIPES
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|Init