I. Pressure Sensor
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.
Two-wire pressure sensors are relatively simple to wire, and most customers know how to connect them. One wire connects to the positive terminal of the power supply, and the other wire, which is the signal wire, connects to the negative terminal of the power supply through the instrument. This is the simplest method. Three-wire pressure sensors add one more wire to the two-wire system, which connects directly to the negative terminal of the power supply, making it slightly more complicated. Four-wire pressure sensors definitely have two power input terminals and two signal output terminals. Four-wire sensors mostly provide voltage output rather than 4~20mA output; 4~20mA outputs are called pressure transmitters, and most are made in a two-wire configuration. Some pressure sensor signal outputs are unamplified, with a full-scale output of only tens of millivolts, while some pressure sensors have internal amplification circuits, providing a full-scale output of 0~2V. As for how to connect to the display instrument, it depends on the instrument's range. If there is a range compatible with the output signal, you can measure directly; otherwise, a signal adjustment circuit is needed. Five-wire pressure sensors are not much different from four-wire sensors, and five-wire sensors are less common in the market.
II. Application Areas of Pressure Sensors
Pressure sensors are widely used in various industrial automation environments and are a commonly used sensor in industrial practice. They are applied in numerous industries including water conservancy and hydropower, production automation, aerospace, intelligent buildings, shipbuilding, machine tools, pipelines, military, petrochemicals, oil wells, power, and railway transportation. Below, we will introduce some application examples of pressure sensors.
1. Application of pressure sensors in weighing systems
Pressure sensing technology is increasingly being used in commercial weighing systems for industrial control. In many pressure control processes, it is frequently necessary to collect pressure signals and convert them into electrical signals suitable for automated control. Pressure control devices made with pressure sensors are generally called electronic weighing systems, which are becoming increasingly important as online control tools for material flow in various industrial processes. Electronic weighing systems can be used for online inventory control and financial settlement, collecting and transmitting data on material flow during the production process to a data processing center. They can also be integrated into the product manufacturing process to optimize production and improve product quality.
In the automatic control of the weighing process, pressure sensors are required to be not only reliable, have good dynamic response, and strong anti-interference capabilities, but also be able to sense gravity signals. The signals provided by the pressure sensor should be directly displayed, recorded, printed, stored, or used for feedback adjustment and control by the detection system. The pressure sensor and measuring circuitry are integrated using integration technology, greatly reducing the overall size of the device. Furthermore, the development of external shielding technology will ensure the anti-interference capability of the weighing pressure sensor, further improving the degree of automation in the weighing process.
2. Application of pressure sensors in the petrochemical industry
Pressure sensors are among the most commonly used measuring devices in petrochemical automation control. Almost all applications of pressure sensors in large-scale chemical projects include: high temperature, low temperature, gauge pressure, high pressure, differential pressure, absolute pressure, micro differential pressure, as well as remote flange pressure sensors made of various materials and with special processing.
In the petrochemical industry, the demand for pressure sensors primarily focuses on reliability, stability, and high accuracy. Reliability, along with many additional requirements such as range ratio and bus type, depends on the transmitter's manufacturing technology, structural materials, and structural design. The stability and high accuracy of the pressure transmitter are mainly guaranteed by the stability and measurement accuracy of the pressure sensor. The petrochemical industry's requirements for pressure sensors are reflected in four aspects: measurement accuracy, fast response, temperature characteristics, hydrostatic characteristics, and long-term stability.
