Page 580 - Air and Gas Drilling Manual

11-18 Air and Gas Drilling Manual
,
) (604 41
. )
604
30
14
.41
P ipp (,100 ) 2 ( ,910 000 (. 0 019 ) (. 0 667 ) 2 e 2 (. 0 019 ) (. 0 667 ) 1 . 05
2
e 604 .41
2
P ipp 31 470 lb/ft abs
,
P ipp
p ipp
144
.
p ipp 218 6 psia
On-Off Action of Air Hammer
Using Equation 4-11, the approximate specific weight of the air inside the drill
collars as it enters the air hammer is determined from P . This is
ipp
0
(,470 ) ( . )
31
1
ah
41
(53 .36 ) (604 . )
0 976 lb/ft 3
.
ah
The inside diameter of the drill collars above the air hammer entrance is
d 5 2 8125 inches
.
d 5
D
5
12
D 5 0 234 ft
.
The cross-section area of the inside of the drill collars is
2
A 0 234
.
dci
4
.
A dci 0 0430 ft 2
The approximate velocity of the compressed air inside the drill collars is