Differential pressure transmitters achieve precise measurement and standardized output of fluid or gas differential pressure through a precise mechanical electrical signal conversion mechanism. The core process can be divided into four stages: pressure transmission, diaphragm deformation, capacitance conversion, and signal processing.

1. Pressure transmission mechanism

The differential pressure transmitter adopts a double-sided isolation diaphragm structure. When fluid or gas pressure acts on the diaphragm, the pressure is transmitted to the central measuring diaphragm through the sealing liquid (such as silicone oil) inside the diaphragm. Sealing fluid not only ensures non-destructive transmission of pressure, but also serves to isolate the measured medium, preventing corrosive or high viscosity media from directly contacting the sensor and extending equipment life.

2. Membrane deformation and displacement generation

The central measuring membrane is a tensioned elastic element that undergoes deformation under the pressure difference on both sides. The displacement is proportional to the differential pressure value, and the maximum displacement is usually controlled within 0.1mm to ensure linear response and measurement accuracy. The membrane material (such as 316 stainless steel) needs to have high elastic modulus and fatigue resistance to adapt to long-term high-frequency vibration environments.

3. Changes in capacitance and signal conversion

The displacement of the membrane changes the distance between the capacitor plates, forming a differential capacitor. The pressure difference on both sides causes the diaphragm to tilt towards the low-pressure side, resulting in a decrease in the capacitance on the high-pressure side and an increase in the capacitance on the low-pressure side, producing a capacitance difference proportional to the differential pressure. The circuit system detects the difference and converts it into an initial electrical signal.

4. Signal processing and standardized output

After amplification, filtering, and other processing, the initial electrical signal is converted into a 4-20mA DC current signal by a microprocessor. This standard signal has the advantages of strong anti-interference ability and long transmission distance, and can be transmitted to the control system over long distances. At the same time, the microprocessor supports the HART communication protocol, enabling remote parameter setting and fault diagnosis, and enhancing the level of system intelligence.