Classified by structural features, measuring instruments can be divided into the following three categories:
(1) gauge. That is, with a fixed form of reproduction of the quantitative value of measuring instruments, such as measuring blocks, weights, standard batteries, standard resistors, bamboo and wooden straightedge. Line ruler, etc.;
(2) measuring instruments. To be measured quantity is converted into directly observable indicator value equivalent information measuring instruments, such as pressure gauges, flow meters, thermometers, ammeters, voltmeters. Electrocardiograph, etc.;
(3) measurement device. That is, in order to determine the measured value must be the overall combination of measuring instruments and auxiliary equipment, such as mileage meter calibration device, high-frequency microwave power meter calibration device. Classification by metrological use, measuring instruments can also be divided into the following three categories: measurement reference instruments, measurement standards, work measuring instruments.
Measuring instruments is a basic content of metrological research, is the material basis for measurement. In the international arena, measuring instruments and measuring instruments is a synonymous term, it is defined as "individually or together with auxiliary equipment used to carry out the measurement of the apparatus", in our country measuring instruments are measuring instruments, also known as active; measuring instruments and gauges, also known as passive.
Measuring instruments and measuring devices, according to the technical performance and use of measuring instruments can be divided into benchmarks, standards and general measuring instruments.
(1) benchmark measuring instruments
Measurement 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. Recognized by the international agreement, in the international community as a given amount of all other standards based on the standard known as the international benchmark, officially recognized by the state, in the country as a given amount of all other standards based on the standard known as the national benchmarks, benchmarks measuring instruments usually have the main benchmarks to testify to the benchmarks of the benchmarks of the secondary benchmarks of the reference reference benchmarks and the work of the benchmarks of the points.
The main features of the benchmark measuring instruments:
1 in line with or close to the definition of the unit of measurement based on the basic principles.
2 good reproducibility and the definition of the realization of maintaining or reproducing the unit of measurement or its multiples or fractions of the highest contemporary or national accuracy.
3 Stability of the measurement characteristics over time.
4 The ability to transmit, by some method or means, the unit of measure, or its multiples or fractions, defined to achieve maintenance or reproduction.
(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 values used as a reference to the physical gauge. Measuring instrument standard material or measuring system
China's customary for the benchmark is higher than the standard, which is measured from the characteristics to consider the measurement of standards at all levels must be directly or indirectly accept the national benchmark for the transfer of quantitative value and can not be set on their own.
(3) ordinary measuring instruments
Ordinary measuring instruments refers to the general day-to-day work of the measuring instruments it can be obtained for a given amount of measurement results. Classification, measuring instruments can be divided into the following three categories
(1) the scope of Class A measuring instruments: 1. the company's highest standard of measurement and measurement of standard instruments; 2. for trade settlement, safety and security, medical and health care and environmental monitoring, and included in the scope of mandatory verification of work measuring instruments measuring instruments; 3. production process and quality inspection of the key parameters of the measuring instruments; 4. In and out of the plant material accounting measuring instruments; 5. Precision testing of high accuracy or frequent use and poor reliability of measuring instruments.
Type A measuring instruments, including: a flat crystal, zero-level cutter ruler, level gauge gauge, right-angle ruler gauge, measuring tape gauge, percent gauge gauge, micrometer gauge, self-collimator, vertical optical meter.
(2) the scope of Class B measuring instruments: 1. safety, health care and environmental monitoring, but not included in the mandatory verification of the scope of measuring instruments; 2. production process is not a key parameter in the process of measuring instruments; 3. product quality of the general parameters of the detection of measuring instruments; 4. two or three energy measurement measuring instruments; 5. material management within the enterprise measurement instruments. Measuring instruments for material management within the enterprise.
B class measuring instruments include: calipers, micrometers, measuring tape, micrometers, levels, right-angled ruler, ruler, 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, scales, voltmeters, ammeters, megohmmeters, power meters, bridges, resistance boxes, current detectors, multimeter, standard resistor box, calibration signals Standard resistance box, calibration signal generator, ultrasonic flaw detector, spectrophotometer and so on.
(3) the scope of measuring instruments in category C: 1. low-value consumable, non-compulsory calibration of measuring instruments; 2. the company's living area with the internal energy distribution of measuring instruments, measuring instruments for auxiliary production; 3. in the use of measuring data in the process of measurement of the measurement of imprecise requirements; 4. the national measurement of the administrative department expressly allowed a one-time calibration of the measuring instruments.
Category C includes steel ruler, curved ruler, steel tape measure below 5M.