Types of instrumentations
The measuring device is called the device, koyotory serves for comparison of the measurand with the unit of measure. Measuring apparatuses can be classified by the following signs:
- measurand sort;
- way of counting;
- accuracy class
By the nature of the measurand control and measuring priyobor separate into the following main groups:
- for temperature measurement;
- for measurement of pressure and depression (vacuum);
- for measurement of quantity and the consumption of liquids, vapors and gases;
- for measurement of levels of liquids and loose bodies;
- for high-quality measurements (density, humidity, soyostav of gases, etc.).
On the way of counting distinguish devices:
- with manual aiming;
- summing up;
With manual aiming (called by also kompariruyushchy) treat devices such, at which is at measurement, comparison of izyomeryaemy size with samples or measures is carried out with direct participation of the person (for example, kettlebell scales, the disappearing-filament optic pyrometer).
Detection instruments at the time of measurement specify the measurand znayocheniye, these values are determined vizualyyono by scales — reading devices of the device by means of the index (arrow) moving along the scale (or by means of the rotating dial and the motionless index). On the design detection instruments are separated on statsioyonarny (panel board) and figurative. Fixed instruments serve for continuous control of the measurand. Field instruments are used or when measurements are performed periodically or incidentally with considerable periods between measurements, or for checking of fixed instruments.
Autographic apparatuses automatically write down results of measurement on the moving paper tape or the disk. This record usually represents the line which shows how изменялось value of the measurand for the expired time. On this record (chart) it is possible to keep account of the consumption of raw materials or the vyyopusk of products, to judge whether tekhnologiyochesky process was correctly conducted, to establish the equipment cause of accident.
Summation instruments (counters, integrators) show total value of the measurand which is determined usually by the calculating mechanism. Counters allow to consider amount of the spent energy, couple, waters, gas, etc.
The signaling devices at achievement measured veliyochiny preset values give the light or sound signal.
To destination produce the following devices: technical (or operational), control, laboratory, obraztsoyovy and reference.
Industrial common industrial measuring apparatuses yavyolyatsya by the service instruments applied on production. They are simple on the design, are reliable in work, are supplied with accurate scales with large digitization, are produced on classes of the tochnosyota from 0,5 to 4,0.
Control and substandard instruments are applied to the poyoverka of industrial instruments and also during the setup and research works. Usually calibrate with instruments of intermediate accuracy industrial instruments on site of their installation, and laborayotorny devices - in laboratory. Control and substandard instruments are produced higher classes of the tochyonost, than industrial instruments, namely 0,5 and 1.
Calibration and model instruments are used to checking of measuring apparatuses. Standards have the highest accuracy. Basic purpose of standards - to store and reproduce ediyonitsa with the highest accuracy. Model devices in the pokazayoniya give real value of the measurand. But they have the smaller accuracy, than calibration instruments, assignment of model devices - transfer at poyomoshch of checking and graduation of the correct units of measure from standards to other devices, their classes of accuracy 0,02-0,4.
One of the most important characteristics of measuring apparatuses is the sensitivity of the device. Sensitivity of the device is called the relation of size of linear or angular movement of the arrow (or the device feather) to change of value of the measurand which caused this movement.
The chuvstvitelyyonost usually in numbers of division of the instrument scale is expressed. For example, if the draft gage is supplied with the scale having 50 divisions, and to the full otkloyoneniye of the arrow of the device there corresponds depression change, equal 1000 mm w.g. (9810 N/sq.m), average sensitivity of the device
t. е 1 division into 20 mm w.g. (or 1 division on 196).Top