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What is the difference between pressure transmitters and pressure gauges?

Post: 2020-02-29

Pressure transmitter selection piezo-resistance type sensitive core, small size, high agility, good stability, its characteristics first reflected in its sensitive core.By definition, the principle of piezoresistive transmitter is that the sensitive core generates resistance change after being compressed, and then converts the resistance change into standard signal output by expanding the circuit.

Sensitivity is a major characteristic of a pressure transmitter, so its sensitivity should be considered first when selecting a pressure transmitter.The current pressure transmitter is very different in principle and structure. How to choose the appropriate pressure transmitter reasonably according to the detailed measurement purpose, measurement object and measurement environment is the first problem to be dealt with in the measurement of a certain quantity.

In general, within the linear range of pressure transmitters, the sensitivity of the transmitter is expected to be as high as possible.Because only when the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, which is conducive to signal processing.However, it should be noted that the sensitivity of the transmitter is high, and the external noise that has nothing to do with the measurement is simply mixed in, which will also be expanded by the expansion system, affecting the measurement accuracy.Therefore, the transmitter itself should have a higher signal-to-noise ratio to reduce the disturbance signal introduced from the outside as far as possible.

The sensitivity of the transmitter can be said to be directional.When the measured vector is a single vector and its directivity is highly required, transmitters with small sensitivity in other directions should be selected.If the measured vector is multi-dimensional, the cross sensitivity of the transmitter is required to be as small as possible.

Generally speaking, when the pressure transmitter is confirmed, the corresponding measurement method and measurement equipment can be confirmed.The success or failure of measurement results, to a large extent, will depend on the choice of transmitter is reasonable.

The pressure transmitter is manufactured by encapsulating the silicon piezoresistive pressure sensor with a barrier in a stainless steel case.It can convert the felt liquid or gas pressure into standard electrical signal for external output. The pressure transmitter is widely used for on-site measurement and control of power supply/drainage, heat, petroleum, chemical, metallurgy and other industrial processes.Pressure transmitter can be used with various types of moving coil indicator, digital pressure gauge, electronic potentiometer, pressure transmitter can also be used with various active regulation system or computer system.

The difference between pressure transmitter and pressure gauge is as follows:

1. Pressure transmitter is used in active control.The device converts the pressure signals of gas and liquid into the standard current and voltage signals on the pipeline that needs to take pressure, so as to provide the secondary appearance such as alarm device, logger and regulator for measurement, indication and process adjustment.

2. The pressure gauge is directly installed in the pipeline, and the pipeline pressure is directly selected.

The pressure point selection requirements of the pressure transmitter conform to the following rules:

1. When measuring the gas pressure, the pressure point should be in the upper half of the process pipeline.

2. When measuring the liquid pressure, the pressure point should be within the range of 0 ° ~45 ° between the lower half of the process pipeline and the horizontal center line of the process pipeline.

3. When measuring the steam pressure, take the pressure point within the range of 0 ° ~45 ° between the upper and lower half of the process pipeline and the horizontal center line of the process pipeline.

4. The device orientation of pressure source parts should select the stable pipe segment in the process medium flow beam.

5. When the pressure source part and the temperature source part are in the same pipeline, the pressure source part shall be installed upstream of the temperature source part.

6. The end of the pressure source shall not exceed the inner wall of the process equipment and process pipeline.

7. When measuring the pressure of turbidified media such as dust, solid particles or sediments on the vertical process pipe, the source parts should be inclined to the upward device, the included Angle with the horizontal line should be greater than 30 degrees, and it is appropriate to form an acute Angle device by downstream flow in the horizontal process pipe.

8. The position of the pressure transmitter device should be light enough and easy to operate and maintain. It is not suitable for the device to be disturbed by oscillation, humidity, high temperature, corrosive and strong magnetic field.

9. The position of pressure transmitter device should be as close to the source as possible.The height of the device for measuring the low pressure transmitter should be consistent with the height of the pressure point, especially for measuring the liquid medium and condensable gas medium.

10. When measuring the pressure of gas medium, the azimuth of the transmitter device should be higher than the pressure point, and when measuring the pressure of liquid or steam, the azimuth of the transmitter device should be lower than the pressure point, in order to reduce the additional equipment of exhaust and drainage.

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