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Definition of pressure sensor

Mar 29, 2019

Xi'an Huaheng Instrument carries out a description of the definition of pressure sensor:

The national standard GB7665-87 defines the sensor as: "A device or device that can be measured and converted into a usable signal according to a certain rule, usually composed of a sensor component and a conversion component." The function of the pressure sensor is a detecting device that can sense the measured information and can transform the detected information into an electrical signal or other required forms of information output according to a certain law to meet the information transmission and processing. Requirements for storage, display, recording, and control. It is the first step in achieving automatic detection and automatic control.


Second, the classification of voltage force sensors


At present, there is no unified classification method for sensors, but the following three types are commonly used:


1. According to the physical quantity of the sensor, it can be divided into sensors such as displacement, force, speed, temperature, flow, and gas composition.


2, according to the working principle of the sensor, can be divided into resistance, capacitance, inductance, voltage, Hall, photoelectric, grating, thermocouple and other sensors.


3. According to the nature of the sensor output signal, it can be divided into: switch type sensor whose output is switch quantity ("1" and "0" or "on" and "off"); the output is analog type sensor; the output is pulse or The digital sensor of the code.


1. According to the measured physical quantity: such as: force, pressure, displacement, temperature, angle sensor, etc.;


2. According to the working principle of the sensor: such as: strain gauge sensor, piezoelectric sensor, piezoresistive sensor, inductive sensor, capacitive sensor, photoelectric sensor, etc.;


3. According to the way the sensor converts energy:

(1) Energy conversion type: such as: piezoelectric type, thermocouple, photoelectric sensor, etc.;

(2) Energy control type: such as: resistive, inductive, Hall-type sensors and thermistors, photoresistors, humidity-sensitive resistors, etc.;


4. According to the working mechanism of the sensor:

(1) Structure type: such as: inductive, capacitive sensor, etc.;

(2) Physical properties: such as piezoelectric, photoelectric, various semiconductor sensors, etc.;


5. According to the form of the sensor output signal:

(1) Analog: The sensor output is an analog voltage;

(2) Digital: The sensor output is a digital quantity, such as an encoder type sensor.


Third, the pressure sensor selection:


The pressure sensor function is a measuring instrument that converts a pressure variable into a standardized output signal that can be transmitted, and has a given continuous function relationship between the output signal and the pressure variable. It is mainly used for the measurement and control of pressure parameters in industrial processes.

1. Confirm the type of measurement pressure. The pressure types mainly include gauge pressure, absolute pressure, differential pressure, etc.; gauge pressure refers to the pressure based on atmospheric pressure, which is less than or greater than atmospheric pressure; absolute pressure refers to absolute pressure zero as the benchmark and higher than absolute pressure zero. Pressure; differential pressure is the difference between two pressures.

2. Confirm the pressure range to be tested. In general, the actual measured pressure is 80% of the measurement range of the pressure sensor.

3. Confirm the maximum overload of the system. The maximum overload of the system should be less than the overload protection limit of the pressure sensor, otherwise it will affect the service life of the product or even damage the product. American precision pressure sensors have overload protection of 2 times the measurement range.

4. Confirm the accuracy level. The measurement error of the pressure sensor is divided according to the accuracy level. Different accuracy corresponds to different basic error limits. In practical applications, the selection is based on the control requirements of the measurement error and in accordance with the principle of economic application.

5. Confirm the working temperature range. The temperature of the measuring medium should be within the working temperature range of the pressure sensor. If it is used over temperature, it will produce large measurement error and affect the service life. In the production process of the pressure sensor, the temperature influence will be measured and compensated to ensure the product. Measurement errors due to temperature are within the accuracy level requirements. In the case of high temperature, consider choosing a high temperature type pressure sensor or taking auxiliary cooling measures such as installing a condenser tube or a radiator.

6. Confirm the compatibility of the measuring medium with the contact material. In some measurement applications, the measuring medium is corrosive. In this case, materials compatible 

with the measuring medium or special processing are required to ensure that the pressure sensor is not damaged.

7. Confirm the pressure interface form.