Page 664 - Air and Gas Drilling Manual

A-2 Air and Gas Drilling Manual
small as long as we are analyzing a problem on or quite near the earth’s surface.
Fluid mechanics problems for other locations, such as the moon where g is very
different than on the earth, can be handled by the methods presented in this text if
proper consideration is given to the value of g.
The metric SI is known as a mass system, since mass is not dependent on the
gravitational system. Indeed, the gravitational acceleration g at the location either on
the earth’s surface on moon’s surface needs to be known in order to handle specific
problems.
Table A-1: Definitions of English system quantities

2
Force 1 lb = 1 slug-ft/sec
2
Area 1 acre = 43,560 ft
Energy 1 Btu = 778 ft-lb
Flowrate 1 cfs = 448.83 gpm
Length 1 ft = 12 inches
1 yd = 3 ft
1 statute mile = 5,280 ft
1 nautical mile = 6,000 ft
2
Mass 1 slug = 1 lb-sec /ft
Power 1 hp = 550 ft-lb/sec = 0.708 Btu/sec

Velocity 1 mph = 1.467 ft/sec
1 knot = 1.689 ft/sec = 1.152 mph
3
Volume 1 ft = 7.48 U.S. gal
3
3
1 U.S. gal = 231 in = 0.1337 ft (8.34 lb of water)
1 British imperial gal = 1.2 U.S. gal (10 lb of water)
Weight 1 U.S. (short) ton = 2,000 lb
1 British (long) ton = 2,240 lb