Category A measuring instruments include: a flat crystal, zero-level cutter ruler, level checker, ruler checker, measuring tape checker, percentage gauge checker, percentage gauge checker, micrometer checker, self-collimating instrument, vertical optical meter, etc..
Category B measuring instruments include: calipers, micrometers, measuring tape, micrometers, levels, right-angles, plug gauges, levels, latitude and longitude, welding inspection tape, ultrasonic thickness gauge, more than 5M tape measure, as well as thermometers, pressure gauges, force gauges, tachometers, scales, hardness testers,
Balance, voltmeter, ammeter, megohmmeter, electric power meter, bridge, resistance box, Current Detector, Multimeter, Standard Resistance Box, Calibration Signal Generator, Ultrasonic Flaw Detector, Spectrophotometer and so on.
Category C includes steel straightedge, curved ruler, steel tape measure below 5M.
Categorized by structural features, measuring instruments can be divided into the following three categories:
1, gauge is that with a fixed form of reproducing the value of the measuring instruments, such as measuring blocks, weights, standard batteries, standard resistors, bamboo and wood straightedge. Line ruler, etc.;
2, measuring instruments. The amount to be measured is converted into directly observable indicator value equivalent information measuring instruments, such as pressure gauges, flow meters, thermometers, ammeters, voltmeters. Electrocardiograph, etc.;
3, measurement devices. 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.
Reference to the above? Baidu Encyclopedia - Measuring Instruments