This Metric Practice Guide deals with the conversion@ from one system of units to another@ of quantities that are in general use@ and includes the units most frequently used in the various fields of science and industry. The conversion factors given are from U.S. customary units2 to those of. the International System of Units:3 which is officially abbreviated as SI in all languages. The recommendations contained herein4 are based upon the following premises@ which are believed to represent the broadest base for general agreement among proponents of the major metro logy systems: That for most scientific and technical work the International System of Units is generally superior to other systems; and that this system is more widely accepted than any other as the common language in which scientific and technical data should be expressed. This is particularly true for the fields of electrical science and technology since the common electrical units (ampere@ volt@ ohm@ etc.) are SI units. That various U.S. customary units@ particularly the inch and the pound@ will continue to be used for some time. That unit usage can and should be simplified: that one means toward such simplification is the elimination of obsolete and unneeded units: and that another is a better understanding of the rational links between SI units and units of other systems. 2This and other terms are defined in Appendix A I. 3 The International System of Units (System International! d' Unites) (51) is described in Appendix A2 . 4This section IS adapted from IEEE Recommended Practice for Units in Published Scientific and Technical Work. IEEE Spectrum. March 1966. pp. 169-173.
API 2563-1970 history
1970API 2563-1970 METRIC PRACTICE GUIDE (A GUIDE TO THE USE OF SI-THE INTERNATIONAL SYSTEM OF UNITS)