Page 617 - Air and Gas Drilling Manual

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144
p p isp 219 0 psia Chapter 11: Specialized Drilling Equipment 11-55
.
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Annulus Passage Around the Gear Box
The pneumatic turbine motor annulus passage around the gear box has an
annulus outside surface diameter of 5.50 inches and an inside surface diameter of
4.70 inches. The length of the annulus section is 15.0 inches. Thus, the annulus
outside diameter, D ano, is
.
d 550 inches
ano
d ano
D ano
12
.
D ano 0 458 ft
The annulus inside diameter, D ani, is
.
d 470 inches
ani
d ani
D ani
12

D ani 0 392 ft
.
The length of the annulus passage, L anp , is
l anp 15 0 inches
.
l anp
L anp
12

L anp 1 250 ft
.
Over the length of the annulus passage the surface roughness is
.
e p 0 00015 ft
With the above, Equation 6-73 becomes