ASME B89.1.7-2009 pdf free download.Performance Standard for Steel Measuring Tapes.
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 thickness does not cause inaccuracy of measurement.
Certain sections of the measuring tape. especially towards the ends, may be subdivided into submultiple’s of the graduation interval adopted for the whole mcii- 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 US. Customary system. The SI units shall be in meters, centimeters, millimeters. arid multiples or subdivisions thereof. The US. Customary units shall he in feet, inches, and multiples or subdivisions thereof, to include decimal or fractional divisions.
4.6.3 Length of Graduations. In general, as the subdivision ol length becomes smaller, the subdivisions should be indicated by using graduations of shorter length. However, in no case should the length of graduations be less than 0.7 mm cc 0.03 in.
4.6.4 Width. The graduation marks shall not be wider than 50% of the distance between two consecutive minor graduations.
4.7 AddItional Markings
All markings, other than graduations and numbering, should be ro positioned and of such a size as not to interfere with the legibility of the steel measuring tapes.
4.8 Numbering
4.8.1 SIze of Numbers. The size of the numbers denoting the major graduations shall be as brge as practical without reducing the legibility of the graduations. All digits shall be of a style that distinctly differentiates one number from another.
4.8.2 Zero Reference Mark. A tip, ring, honk, or end fitting may be included as a zero relerence mark on the measuring tape. In this cas. the numbering shall he positioned to accommodate the zero reference mark. Figure 1 illustrates the standard practice for the zero reference marking on various styles of tapes.
4.8.3 DIstinguishing of Numbers. Numbers derioting each multiple or subdivision of a unit of k-ngth shall be distinguishable from each other by one or more of the following: size, color, or style. The numbers designating the same multiple or subdivision shall be of the same size and style, except where these are reduced to accommodate other markings.
4.9 DefInition of the Calibrated Distance
The calibrated distance between graduations shall be taken as the intervals between the centerlines of pairs of gradua Lions at the edge of the tape where the shortest graduations appear.
In the absence of short graduations, the calibrated distance is defined to be the intervals between centerlines of the graduations at the bottom edge of the tape when viewed with the numbers right side up. The distance is defined at 20°C. when the tape is fully supported with specified tension (possibly zero) applied (see section 6).
It should be noted that cases exist that are not covered above. In these cases the owner should specify the definition of the calibrated distance. In the absence of a clear definition, the calibrating technician shall use his or her discretion in defining the calibrated distance, and the definition of the calibrated distance shall be documented in the calibration report.
This Standard applies to numerous tapes, as described in paras. 5.1 through 5.4.
5.1 Retractable Steel Tape Rule
A retractable steel tape rule is a graduated and numbered flexible steel blade with either a curved cross section that provides a measurable degree of stiffness, or a flat rectangular cross section, with an end fitting and optionally a spring motor within a case. It is to be constructed in a manner that alIos’s easy extension and provides for quick retraction into the case.
5.2 Measuring Tape — Steel General Purpose
A steel general purpose tape is a graduated and numbered flexible steel blade with an end fitting and a case or reel having a winding drum and handle, or other mechanism, for retraction of the tape into the case.
Commentary: Ambient operating temperature limits are intended only to be a guideline. The component temperature of each part of the lifter must be considered when the device is operating in an environment outside the limits defined in para. 1-4.7. The effects of dust, moisture, and corrosive atmospheric substances on the integrity and performance of a lifter cannot be specifically defined. These design considerations must be evaluated and accounted for by the lifting device manufacturer or qualified person.
Ilie design categories defined in paras. 2-2.1 and 2-12 provide for different design factors that establish the limits to be used in the design. The design factors are given in para. 3-1.3.
Lifters shall be designed to Design Category H, unless a qualified person determines that Design Category A is appropriate.
Commentary: When selecting a Design Category. consideration shall be given to all operations that will affect the lifting device design. The discussions of the Design Categories below and in Commentary for para. 3.1.3 refer to considerations given to unintended overloads in development of the design factors. These comments are in no way to be interpreted as permitting a lifting device to be used above its rated load under any circumstances other than for load testing in accordance with ASME B30.20 or other applicable safety standards or regulations.
2-2.1 Design Category A
(a) Design Category A should be designated when the magnitude and variation of loads applied to the lifter are predictable, where the loading and environmental conditions are accurately defined or not severe.
(b) Design Category A lifting devices shall be limited to Service Class 0.
fc) The nominal design factor for Design Category A shall be in accordance with para. 3-1.3.
Commentary: The design factor specified in Chapter 3 for Design Category A lifters is based on presumptions of rare and only minor unintended overloading.