ASME B89-1-7:2009 pdf download

ASME B89-1-7:2009 pdf download.Performance Standard for Steel Measuring Tapes
1 SCOPE
This Standardspecifiestherequirementsforsteelmea- suring tapes, with respect to units (SI and U.S. Customary), graduations, numbering, designations, and accuracy requirements.
2 DEFINITIONS
accuracy: closeness of agreement between a measured quantity value and a true quantity value ofa measurand. Accuracy is a qualitative concept. (VIM 2.13) graduations: marks or lines perpendicular to the edge of a measuring tape denoting increments of measure. intermediate graduation: a graduation mark denoting an increment of measure that falls between the major and the minor graduations (e.g., inch or centimeter). major graduation: a graduation mark denoting the largest increment of measure (e.g., feet or meter). maximum permissible errors (MPE): extreme value of mea- surement error, with respect to a known reference quan- tity value, permitted by specifications or regulations for agivenmeasurement,measuringinstrument, ormeasur- ing system. (VIM 4.26) minor graduation: a graduation mark denoting the small- est increment of measure (e.g., fraction of an inch, deci- mal inch, or millimeter). plumb bob: when used with a measuring tape, a weight with a tapered or flattip on the bottom thatis suspended from the tape. tension: a force that tends to stretch or elongate some- thing, or a measure of such a force. NOTE: The measure of force in the U.S. Customary system is the pound (lbf); the measure of force in the SI system is the newton (N). Traditionally, the tension (a force) has been referred to in units of pounds and kilograms. Pound (or pound-force) is proper. In the SI system of units, the kilogram is the unit of mass and the newton is the unit offorce. Inthis Standard, the tension for tapes graduated in SI units is specified in kilograms, in order to maintain continuity of reference to master tape calibration data. The corresponding force in newtons is equal to the applied mass in kilograms multiplied by the acceleration due to gravity, g.
4 GENERAL REQUIREMENTS
All steel measuring tapes covered by this Standard shall conform to the requirements in paras. 4.1 through 4.9. 4.1 Straight and Parallel Steel measuring tapes shall be made so that when stretched out on a flat surface the edges are nominally straight and parallel. 4.2 Ease of Reading All steel measuring tapes shall be clearly marked to facilitate easy and correct reading. 4.3 Background The graduations and numbering shall be in sharp visual contrast with the background. 4.4 Compatibility There shall be compatibility between the legibility of graduations and the size and form of numbers, when related to the distance at which the measuring tape is normally read. 4.5 Measurement Units Unit names and symbols displayed on metric measuring tapes covered by this Standard shall be con- sistent with IEEE/ASTM SI 10-2002. 4.6 Graduation Requirements Along the nominal length, the measuring tape shall carry clear, regular, and indelible graduations and num- bering, to ensure simple and unambiguous reading. Some unnumbered graduations may extend beyond the major graduation marks at the ends of the measuring tape. Graduations extending to the left of zero and to therightofthe lastmajorgraduationarenotto beconsid- ered part of the tape for calibration purposes. 4.6.1 Graduation Quality. When the graduations are lines, they shall be visually straight, perpendicular to the axis of the measuring tape, and all of the same thickness. The thickness of each line shall be constant throughout its length. The lines shall be such that they form a distinct and clear graduation and that their thick- ness does not cause inaccuracy of measurement. Certain sections of the measuring tape, especially towards the ends, may be subdivided into submultiples of the graduation interval adopted for the whole mea- sure. In that case, the thickness of the lines may be less in the areas of reduced graduation intervals than in the rest of the measuring tape. 4.6.2 Arrangement. The measuring tape shall be divided by graduations of units consistent with the SI system or U.S. Customary system. The SI units shall be in meters, centimeters, millimeters, and multiples or subdivisions thereof. The U.S. Customary units shall be in feet, inches, and multiples or subdivisions thereof, to include decimal or fractional divisions. 4.6.3 Length of Graduations. In general, as the sub- division of length becomes smaller, the subdivisions should be indicated by using graduations of shorter length. However, in no case should the length ofgradua- tions be less than 0.7 mm or 0.03 in.