Classification by level, measuring instruments can be divided into three categories: Class A measuring instruments, Class B measuring instruments, Class C measuring instruments.
1, Class A measuring instruments include: a flat crystal, zero-level cutter ruler, level gauge gauge, right-angle ruler gauge, percent gauge gauge, percent gauge gauge, micrometer gauge, self-collimator, vertical optical meter.
2, Class B measuring instruments include: calipers, micrometers, measuring tape, micrometers, levels, rulers, tape measure, level, latitude and longitude, welding inspection tape, ultrasonic thickness gauge, more than 5M tape measure.
And thermometers, pressure gauges, force gauges, tachometers, scales, hardness testers, balances, voltmeters, ammeters, megohmmeters, electric power meters, bridges, resistance boxes, current detectors, multimeters, standard resistance boxes, calibration signal generators, ultrasonic flaw detectors, spectrophotometers, etc..
3, C category includes steel straightedge, curved ruler, 5M below the steel tape measure, etc..
Expanded
By metrological use of classification, measuring instruments can also be divided into the following three categories: measuring reference instruments, measuring standards, work measuring instruments.
1, the benchmark measuring instruments: measurement of the benchmark is in a particular field, with the highest contemporary measurement characteristics of its value does not have to refer to the same amount of other standards, and is designated or commonly recognized measurement standards.
2, measurement standards: measurement standards are defined in order to achieve the realization of the preservation or reproduction of the amount of units or one or more measurements used as a reference to the physical gauge. Measuring instrument standard material or measurement system.
3, ordinary measuring instruments: ordinary measuring instruments refers to the general daily work used in measuring instruments it can be obtained for a given quantitative measurement results.
Baidu Encyclopedia - Measuring Instruments