Page 6 - Drilling a Straight Hole

Petroleum Extension-The University of Texas at Austin
Units of Measurement

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hroughout the world, two systems of measurement dominate:
Tthe English system and the metric system. Today, the United
States is one of only a few countries that employ the English system.
The English system uses the pound as the unit of weight, the foot
as the unit of length, and the gallon as the unit of capacity. In the
English system, for example, 1 foot equals 12 inches, 1 yard equals
36 inches, and 1 mile equals 5,280 feet or 1,760 yards.
The metric system uses the gram as the unit of weight, the metre
as the unit of length, and the litre as the unit of capacity. In the metric
system, 1 metre equals 10 decimetres, 100 centimetres, or 1,000 mil-
limetres. A kilometre equals 1,000 metres. The metric system, unlike
the English system, uses a base of 10; thus, it is easy to convert from
one unit to another. To convert from one unit to another in the English
system, you must memorize or look up the values.
In the late 1970s, the Eleventh General Conference on Weights
and Measures described and adopted the Système International (SI)
d’Unités. Conference participants based the SI system on the metric
system and designed it as an international standard of measurement.
The Rotary Drilling Series gives both English and SI units. And
because the SI system employs the British spelling of many of the terms,
the book follows those spelling rules as well. The unit of length, for
example, is metre, not meter. (Note, however, that the unit of weight
is gram, not gramme.)
To aid U.S. readers in making and understanding the conversion
system, we include the table on the next page.

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