I. Pressure Sensors and Their Applications
A pressure sensor is a device or apparatus that can sense pressure signals and convert them into usable electrical signals according to a certain rule.
Pressure sensors typically consist of a pressure-sensitive element and a signal processing unit. Based on different test pressure types, pressure sensors can be classified into gauge pressure sensors, differential pressure sensors, and absolute pressure sensors.
Pressure sensors are one of the most commonly used sensors in industrial practice. They are widely used in various industrial automation environments, including water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace, military, petrochemical, oil wells, power, shipbuilding, machine tools, pipelines and many other industries.
Pressure sensors in hydraulic systems primarily function to achieve closed-loop force control. When the control valve spool moves suddenly, a pressure spike several times the system's operating pressure can form within a very short time. In typical mobile machinery and industrial hydraulics, any pressure sensor will quickly fail if such extreme conditions are not considered in the design. Shock-resistant pressure sensors are required. There are two main methods for achieving shock resistance in pressure sensors: one is using a strain gauge chip, and the other is using an external coil. The first method is generally used in hydraulic systems, mainly because it is easier to install. Another reason is that the pressure sensor must withstand the continuous pressure pulsations from the hydraulic pump.
Pressure sensors are frequently used in safety control systems, primarily in the safety management systems of air compressors. Given the wide variety of sensor applications in safety control, the use of pressure sensors, as a very common type of sensor, is not surprising.
In the field of safety control, applications are generally considered from performance, price, and the safety and convenience of actual operation. Practical experience has shown that pressure sensors are an excellent choice. Pressure sensors utilize mechanical processing technology to mount components and signal conditioners onto a very small chip. Therefore, small size is one of its advantages, as is low price. To a certain extent, it can improve the accuracy of system testing. In safety control systems, installing pressure sensors in the outlet piping to control the pressure from the compressor is a protective measure and a very effective control system. When the compressor starts normally, if the pressure value has not reached the upper limit, the controller will open the inlet to adjust the pressure so that the equipment reaches maximum power.
II. Zeroing the pressure sensor
(I) Zeroing Principle
Zeroing a pressure sensor refers to adjusting the sensor's output value to zero before use, laying an accurate foundation for subsequent experiments and measurements.
The sensor's output value is called "zero drift." In most cases, zero drift is caused by external factors, such as temperature changes, pressure changes, and mechanical vibrations. By zeroing the sensor, the sensor's output value can be returned to zero, eliminating the influence of zero drift and ensuring the accuracy and stability of the sensor's output value.
(II) Calibration Principle
The calibration of a sensor is a process of correcting the error between the sensor's output value and the actual measured value; this error is called "calibration drift".
Sensor calibration is a crucial operation that effectively eliminates sensor drift and improves the sensor's accuracy and measurement capabilities.
During calibration, the sensor's output value needs to be compared with the standard measurement value. The error is eliminated by adjusting the sensor's parameters so that the sensor's output value is consistent with the actual measurement value.
(III) Zeroing Method
1. Use the automatic zeroing function
Modern pressure sensors are typically equipped with an automatic zeroing function, which helps users automatically detect and eliminate zero-point drift of the sensor.
This function typically runs automatically for the first few minutes of operation of the sensor device to ensure that the sensor's output value is stable. If your sensor does not have an automatic zeroing function, you will need to perform zero-point calibration manually. Here are some simple steps:
2. Manually adjust the zero point
Manual zeroing is one of the traditional methods of zeroing, and it is very simple to operate. First, place the sensor in a pressure-free state and connect the pressure sensor to the measuring device.
Then, adjust the sensor output value to zero. When adjusting the zero point, it is necessary to follow the sensor's instruction manual to ensure the accuracy and stability of the sensor output value.
