Pressure transmitters and pressure gauges are widely used in fluid pressure measurement and control in industrial processes. But what is the difference between pressure transmitters and pressure gauges?
Regarding this issue, firstly we need to figure out the definition of pressure transmitter and pressure gauge. Only by understanding their meaning, then we will naturally understand the difference between them.
What Is A Pressure Transmitter?
Definition: A pressure transmitter refers to a pressure sensor whose output is a standard signal. It is an instrument that contacts a pressure variable and converts it into a standard output signal in proportion. The pressure transmitter is mainly composed of three parts: pressure sensing element (also called pressure sensor), measuring circuit, and process connection. It can convert the physical pressure parameters of gas and liquid felt by the pressure sensing element into standard electrical signals (such as 4-20mADC, etc.) to support the secondary instruments such as indicating alarms, recorders, regulators, etc. for measurement, indication and process regulation.
Working Principle: When the pressure directly acts on the surface of the measuring diaphragm, the diaphragm produces a small deformation. The high-precision circuit on the measuring diaphragm transforms this small deformation into voltage output which is highly near proportional to pressure and also proportional to the excitation voltage. The pressure transmitter uses a dedicated circuit processing chip to convert this voltage signal into an industrial standard 4-20mA current signal or 1-5V voltage signal, etc. Since the measuring diaphragm adopts a standard integrated circuit, which contains linearity and temperature compensation circuits, it can achieve high precision and high stability. The transmission circuit adopts a dedicated chip, which can guarantee the output of two-wire 4-20mA current signal, three-wire 0.5V-4.5VDC, 1-5VDC, 0-5VDC, and other voltage output signals.
What Is A Pressure Gauge?
Definition: A Pressure gauge refers to a gauge that uses elastic elements as sensitive elements to measure and indicate pressure higher than the ambient pressure. The application of pressure gauges is extremely common, it covers almost all industrial processes and scientific research fields. It can be seen in many fields of the heating pipe network, oil and gas transmission, water and gas supply system, vehicle repair and maintenance factories, and stores. Especially in the process of industrial process control and technical measurement, because the elastic sensitive element of the mechanical pressure gauge has the characteristics of high mechanical strength and convenient production, the mechanical pressure gauge is more and more widely used.
Working principle: The spring tube pressure gauge is also called the Bourdon tube pressure gauge. The free end of the spring in the pressure gauge is closed, and it drives the sector gear to rotate through the pull rod. When the pressure is measured, the spring tube deforms under the pressure to be measured, so the free end of the spring tube produces displacement. The displacement is proportional to the measured pressure so that the pointer deflects and the pressure value is indicated on the dial. If there is an atmosphere in the gauge case, the pressure measured by the pressure gauge is positive or negative pressure; if the gauge case is sealed and evacuated, the pressure measured by the pressure gauge is absolute pressure. When the Bourdon tube pressure gauge is equipped with an isolation device, it can measure the pressure of high temperature or corrosive, viscous, easy-to-crystallize, and dusty media. In the elastic pressure measuring instruments with high accuracy (such as 0.25 level or better), the elastic elements are mostly made of constant elastic alloy or even quartz glass. The shaft hole of the transmission mechanism is inlaid with gem bearings or rolling bearings. The dial scale is long, and some can be digitally displayed.
The differences between the pressure transmitter and pressure gauge are:
1. The accuracy of standard instruments required for pressure transmitter calibration is much higher than that of pressure gauges.
2. The pressure gauge only needs to verify the relationship between a pair of input and output, while the pressure transmitter may need to verify the relationship between input and communication data.
3. The calibration of pressure gauges must have corresponding measurement qualifications. Pressure transmitters are generally not required except for the manufacturer and new construction.
4. The accuracy of the pressure gauge is poor, there is no output, and it cannot be operated by hand. Generally, it has 5 points to check, and the difference between pressurizing and depressurizing is different. The smart pressure transmitter only needs to calibrate the zero point and full scale generally.
5. The output of the pressure gauge is a scale indication, easy to read. The pressure transmitter is analog output and must be connected to an ammeter of the corresponding accuracy level for display.
From the above description, it is easy to know that the pressure value measured by the pressure transmitter under the same working conditions is more accurate, and the later function expandability is much higher than that of the pressure gauge.
Pressure Transmitters and Pressure Gauge from Micro Sensor
Micro Sensor has over 50 years of experience in developing and manufacturing pressure measurement equipment, including piezoresistive pressure sensors and pressure transmitters, and pressure gauges.
If you are looking for more information on our range of pressure instruments, please contact us via sales@microsensor.cn or leave messages. Our sales engineer will reply to you within 24 hours.
