How much do you know about the history of pressure transmitters?

pressure

Pressure transmitter (pressure transmitter) refers to the output as the standard pressure sensor, is a pressure variable to accept the proportion of the standard output signal conversion instrument. It converts the electrical signal of gas sensors, pressure element liquid pressure into standard physical parameters (such as 4~20mADC), indicating alarm device, recorder, regulator etc. Two instrument for measurement, instructions and process control to supply.

Pressure transmitters are important components used in many industrial equipment to control industrial processes and changes in pressure. The pressure transmitter is used to measure the level, density and pressure of liquid, gas or steam, and then change the pressure signal into 4 ~ 20mADC signal output. Pressure transmitter, capacitive pressure transmitter and diffused silicon pressure transmitter, ceramic pressure transmitter, strain type pressure transmitter, etc..

The pressure transmitter is a field instrument which is directly contacted with the tested medium. It is often used in the environment of high temperature, low temperature corrosion, vibration and impact. It is widely used in pressure measurement and field control in the fields of petroleum, chemical, electric power, steel, light industry and so on.

The development of the pressure transmitter has gone through four stages:

1, the early pressure transmitter adopt large displacement principle, such as mercury float type differential pressure gauge and bellows differential pressure transmitter has a large number of production, the transmitter of low precision and heavy.

In and 1950s, there was a kind of force balanced differential pressure transmitter with higher precision, but the feedback force was small, the structure was complex, and the reliability, stability and vibration resistance were poor.

In the 3 and mid 70s, with the emergence of new processes, new materials and new technologies, especially the rapid development of electronic technology, the displacement transducer with small size and simple structure appeared.

4 and 90s, the rapid development of science and technology, these transmitters measuring accuracy, and gradually to intelligent development, digital signal transmission is more conducive to data acquisition.

Pressure transmitters have been developed to different types, such as capacitive transducer, diffused silicon piezoresistive transducer, differential inductance transducer and ceramic capacitive transducer.

In 1990s, fieldbus technology came into being rapidly, and industrial process control system gradually developed to the field bus control system with two-way communication and intelligent instrument control. A new generation of intelligent pressure transmitter has been produced. Their main features are as follows.

1 、 self compensation function, such as nonlinearity, temperature error, response time, noise and cross induction.

2, self diagnostic function, such as when the power supply, self-test, in operation to achieve the operation check.

3, the microprocessor and the basic sensor have two-way communication function, forming a closed loop work system.

4, information storage and memory function.

5, digital output.

Based on the above functions, the accuracy, stability, repeatability and reliability of the intelligent pressure transmitter have been improved and improved. Its bidirectional communication ability realizes the computer software control and the remote setting range and so on.

Intelligent pressure transmitter is mainly divided into two types: the HART protocol and the 482 or RS232 interface. The intelligent pressure transmitter with HART protocol is to add a special frequency signal on analog signals to realize analog and digital communication simultaneously. With RS232 or 485 intelligent pressure transmitter, the analog signal A/D conversion, calculated by the microprocessor, output by the D/A.