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Pressure hysteresis of a pressure sensor

As an important component of a pressure transmitter, the sensor has three important indicators that can determine whether a pressure transmitter can perform the measurement task well, they are: pressure hysteresis, pressure repeatability, and stability.

Each transmitter must be tested and adjusted when it leaves the factory to make it meet the specified standards, and some performances must be optimized when the sensor leaves the factory, and pressure hysteresis is one of them.

What is pressure hysteresis?

During the calibration process of the pressure transmitter, the pressure is sensed through the isolation diaphragm and the pressure-inducing tube. Although the input quantity will be unified, the direction and size of the pressure loading and unloading of the pressure transmitter in the actual operating conditions The difference will lead to different sizes of the electrical signal output of the pressure transmitter. The misalignment of the input-output characteristic curves in the forward and reverse strokes is the so-called pressure hysteresis.

Factors Affecting Pressure Hysteresis?

First, let’s take a look at the components of the diffused silicon pressure sensor!

Diffused silicon pressure sensor is composed of diffused silicon pressure chip, metal base, ceramic insulating cover, silicon oil, metal isolation diaphragm, etc. When pressure acts on the pressure sensor, materials such as diaphragms and chips will deform to varying degrees. When the pressure is removed, the deformation will disappear.

However, whether it can be restored to the original state depends on the characteristics of the material itself, as well as its processing method, environment and other factors. Therefore, even if the same pressure point is input, the output will not coincide in the forward and reverse strokes.

How to calculate pressure hysteresis?

The size of the hysteresis error is generally determined by the experimental method. Under multiple calibration pressure points within the pressure range, compare the difference between the positive and negative stroke output averages of the pressure calibration points, the absolute value of the maximum average difference and the percentage of the full scale. It is the hysteresis error, and the hysteresis error is also called the return error.

In the specified temperature environment, the pressure of the tested sensor is raised to the upper limit of the measurement, and the pressure is reduced after the pressure is stabilized, and then returns to the zero point. A test point, repeat three or three times to increase and decrease the calibration cycle,

 

How to optimize pressure hysteresis?

High-performance silicon piezoresistive pressure chip, through automatic chip bonding equipment, complete chip bonding, using a special diaphragm aging process, release the internal stress of the isolation diaphragm after stamping, ensure the process consistency of important processes, ensure The excellent performance of raw materials reduces pressure hysteresis and improves the overall performance of pressure sensors through processes such as aging and pressure shock.

 


Post time: Nov-04-2022
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