ASME B89.1.14:2018 pdf free download – Calipers
5.2 Operator
Calipers are manually operated indicating measuring instruments and as such the measurement results are dependent on the skill of the operator. All specifications apply when a reasonably skilled operator uses the caliper in a manner consistent with normal operation of the caliper and in accordance with the manufacturer’s recommendations.
5.3 Zero Setting
Most calipers are equipped with the ability to adjust the zero point. For calipers with adjustable zero points, the metrological characteristics described in this Standard (see para. 5.10) apply when the outside measuring faces are properly brought into contact with each other for zero setting. For calipers without an adjustable zero, e.g, some vernier calipers, there may be a nonzero error when the outside measuring faces are brought together. This error shall be induded in the evaluation of the metrological characteristics without correction.
5.4 Indication
The specified MPE values apply to any and all unique measurement indications made under reasonable use of the caliper. Averaging of several test values or other data treatment is not permitted when determining confor- mance to specifications.
5.7 Traceability
All the length standards, e.g., gage blocks, used in deter- mining the conformance of a caliper to specifications must have metrological traceability per ASME B89.7.5.
5.8 Specifications
Table 5.8-1 lists default MPE values for calipers with a measuring range up to 1 000 mm (40 in.). The MPE values in Table 5.8-1 apply when no specifications are otherwise stated. The caliper manufacturer shall state the MPE values for larger calipers. The caliper manufacturer may also specify different MPE values than shown in this Standard. MPE values stated by the caliper manufac- turer shall conform to the terms, definitions, and symbols in this Standard. Table 5.8-1 includes specifications in both U.S. Customary and SI units. Due to the analog scale interval or digital resolution of a caliper, the conversion between units is not exact. Test values and MPE values shall not be mathematically converted between units when deter- mining conformance to a specification.
5.9 Specialty Calipers
A large variety of specialty calipers are commercially available for measuring items such as tubing, threads, specialized measuring face configurations for use in restricted areas, large diameter measuring faces, spherical shaped measuring faces, and conical measuring faces that allow contact with surfaces that may not be flat or parallel. Specifications for specialty calipers shall be stated by the manufacturer and conform to the terms, definitions, and symbols employed in this Standard and ISO 13385-1.
The default MPE values in Table 5.8-1 are for calipers with a measuring range up to 1 000 mm (40 in.). These MPE values are a function of the measured length and not the measuring range of the caliper. For larger calipers, the MPE values will increase as the measured length increases. For simplicity in practical use, the MPE values increase in a stepwise manner. During confor- mance testing, the measured length is considered nominal when determining the MPE values, and the smaller MPE value always applies for test points that are nominally at the transition between the MPE values. For example, if a gage block used for testing is nominally 200 mm, but the calibrated value is 200.01 mm, the MPE for 200 mm still applies.