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There are many kinds of industrial automation instruments. From the process of information acquisition, transmission, reflection and processing, industrial automation instruments are divided into five categories.

Detection instrument

During the production process, the temperature, pressure, flow rate, material level and other physical quantities of the medium in different parts of the equipment and pipelines change rapidly and are always changing. The detection instrument is used to detect the value of the above-mentioned physical quantities at each instant.

According to the different process parameters measured, the detection instruments can be divided into the following types:

1. Thermometers:

Commonly used temperature measuring instruments include glass thermometers, bimetal thermometers, pressure type (temperature bulb) thermometers, temperature switches, thermocouples, thermal resistances, radiation pyrometers, optical pyrometers, photoelectric colorimetric pyrometers and other radiation thermometers.

2. Pressure gauge:

Pressure measuring instruments are used to detect pressure, vacuum and differential pressure. According to its working principle, it can be divided into: elastic pressure gauge (according to its elastic components, it is divided into spring tube pressure gauge, diaphragm pressure gauge, diaphragm pressure gauge, pressure switch, etc.); sensing pressure gauge (such as resistance type, Capacitive, inductive, Hall-type pressure gauges, etc.); liquid-column pressure gauges (such as U-tube, straight-tube, and inclined-tube pressure gauges); and piston-type pressure gauges with higher accuracy that are usually used to calibrate standard pressure gauges pressure gauge.

3. Flow meter:

There are many kinds of flow measuring instruments, and the most widely used ones are the throttling device and its matching differential pressure flow transmitter. Commonly used throttling devices are orifice plates, nozzles and venturis. Other commonly used flow meters include water meters, rotameters, oval gear flowmeters, target flowmeters, electromagnetic flowmeters, vortex flowmeters, Anuba flowmeters, mass flowmeters, etc.

4. Level meter:

The level meter mainly measures the liquid level of a certain medium or the interface of two liquids with different specific gravity and the material level of solid materials in towers, tanks, and tanks. The most common liquid level gauges are glass tube level gauges, glass plate level gauges, and others include differential pressure level gauges and buoyancy level gauges (such as float level gauges, level switches, and float level gauges). gauges, float level gauges, steel belt level gauges, tank level weighing instruments, etc.). For the level detection of solid materials, there are resistive level meters, capacitive level meters, level switches, weight detection level meters, tuning fork level meters, ultrasonic level meters, radioactive level meters, etc.

5. Composition analyzer:

The composition analyzer is used to verify the composition of the process medium and determine the content of a certain component (or some components up to the whole component). According to its working principle, it can be divided into electrochemical analyzers (such as conductivity meters, industrial acidity meters, zirconia analyzers, etc.), thermal analyzers (such as thermal conductivity analyzers, thermochemical analyzers, infrared analyzers) and magnetic analyzers. Conductive analyzers, photoelectric colorimetric analyzers, mass spectrometers, industrial gas chromatographs, etc.

When installing an online composition analysis instrument, it is generally necessary to preprocess the sample to make the state, temperature, pressure, flow and other parameters of the sample meet the requirements of the working conditions of the analytical instrument. Therefore, it is necessary to configure some filters and dust collectors. , drying container, cooler, rotameter, water seal, valve and pipeline, etc., for general pretreatment of the sample.

For some special media (such as flue gas dirty gas samples, furnace gas and other high-temperature gas samples, heavy oil analysis sampling, corrosive component sampling and environmental testing sampling, etc.), the sampling pretreatment system is more complete. The sampling pretreatment system is called sampling pretreatment device.

In addition, there are also some physical property testing instruments such as moisture meter, hygrometer, density meter, concentration meter, turbidity meter, viscometer, etc., which are often classified as component analysis instruments.

6. Mechanical meter:

Mechanical measuring instruments commonly used in the industry include thickness gauges, thermal expansion detectors, tension detectors, deflection detectors, and shaft vibration, shaft displacement, rotational speed detection devices and scales for rotating machinery (such as large steam turbine compressors, etc.). Weight devices (such as electronic belt scales, belt deviation, slip detection devices, weighing indicators, weighing bagging devices, etc.).

display meter

This type of instrument refers to the instantaneous value of the measured parameter used to indicate or record the measured parameter, such as the ratio meter, millivoltmeter and other moving coil indicators for indicating, digital display instruments and electronic potentiometers for indicating or recording temperature. Differential meter, electronic balance bridge (electronic potentiometer and balance bridge can also be combined with electric regulator or pneumatic regulator to form a composite meter) and accumulative meter with flow accumulation function.

Control instrument

On the one hand, the control instrument receives the measurement signal of the process detection instrument and the transmitter for display, and on the other hand, it sends out the adjustment signal to control the action of the actuator (actuator and regulating valve) to form a closed-loop control system.

Control instruments can be divided into two categories: analog control instruments and digital control instruments according to the type of signal.

1. Analog control instrument

Analog control instruments include base-type instruments, unit combination instruments (pneumatic, electric) and assembled instruments.

In the development process of industrial automation instruments from local detection and display to centralized control, a kind of instrument integrating measurement, display and adjustment functions has been produced. We call it a base-type adjustment instrument or simply a base-type instrument. Such as the indicating recording regulator with a pneumatic regulator and some local regulators with only a single regulating function (such as temperature regulators, pressure regulators, differential pressure regulators, flow regulators).

2. Digital control instrument

Digital control instruments include distributed control system (DCS), industrial control computer (IPC), safety control system (FSC), etc.

Actuator

The actuator, also known as the control valve, consists of the actuator and the valve. According to the power source of the actuator, there are four categories: pneumatic control valve, electric control valve, hydraulic control valve and hybrid control valve. Pneumatic control valves are divided into membrane control valves, piston control valves and long-stroke control valves according to their actuator forms.

Centralized monitoring and control device

The centralized detection device is a device that uses detection elements or detectors to centrally display the measured variable or alarm contact signals; the centralized control device is a device that controls a series of measured variable signals according to the set program. Centralized monitoring and control devices include various data acquisition devices, circuit detection devices, signal alarm devices, safety detection devices, industrial TVs, remote control devices, and sequence control devices.

Centralized monitoring and control devices are generally divided into the following categories:

1. Safety monitoring devices include combustible gas detection and alarm devices, toxic gas detection and alarm devices, flame monitors, automatic ignition devices, combustion safety protection devices, oil leakage detection devices and high resistance detection devices.

2. Industrial TV consists of cameras and their auxiliary equipment (lighting, purging, cooling devices and electric turntables), displays and auxiliary equipment (operators, distributors, compensators, switchers), etc.

3. The remote control device accepts the input variable signal, processes the information, displays the alarm on the screen, and outputs the control signal to the control terminal.

4. Signal alarm devices include various types of signal alarm devices such as flash signal alarm devices, intelligent flash alarm devices, and relay line alarm systems.

5. Sequence control devices include relay interlock protection system, logic monitoring device, sequence control device and intelligent sequence controller.

6. Data acquisition and patrol detection alarm devices include data acquisition devices and patrol detection alarm devices.

Automatically control other equipment

Such equipment mainly includes various (channel type, cabinet type, frame type, screen type) instrument panel, instrument box, console, heat preservation (protection) box, power supply box, etc.

self-control material

Automatic control materials refer to the materials required for instrument installation, and there are many varieties, such as pressure piping (seamless steel pipe, stainless steel pipe, high pressure pipe), gas supply piping (galvanized steel pipe, brass pipe), gas signal piping (copper pipe) , copper pipe cable, nylon pipe cable, take-over box), electrical piping materials (welded steel pipe, galvanized steel pipe), valves, flanges and pipe fittings in various types of piping, electrical equipment materials for automatic control (cables, wires, junction boxes, Electrical equipment and components), instrument cable bridge, used to make instrument equipment brackets, brackets, angle steel, channel steel and other profiled steel metal materials, heat tracing materials and anti-corrosion oil brushing materials.