The working principle of a micro differential pressure transmitter is based on Poisson's law, which states that the pressure of a gas or liquid in a static state is proportional to its density. When there is a differential pressure between two pressure points, the flow rate, liquid level, density and other parameters of the fluid can be calculated by measuring the differential pressure. Differential pressure transmitters typically consist of two pressure interfaces and a measuring chamber. When the medium enters the measurement chamber, it will affect the pressure inside the measurement chamber, causing a change in the pressure inside the measurement chamber. The differential pressure transmitter calculates the differential pressure between two pressure points by measuring the pressure difference inside the measurement chamber, and converts it into a standard signal output. There are two main measurement principles for differential pressure transmitters: one is static pressure measurement, which calculates differential pressure by measuring the static pressure difference between two pressure points; Another type is dynamic pressure measurement, which calculates differential pressure by measuring the dynamic pressure difference generated by the fluid in the pipeline. Static pressure measurement is suitable for measuring low-speed fluids, while dynamic pressure measurement is suitable for measuring high-speed fluids.

In addition, micro differential pressure transmitters are widely used in various self-control environments in industrial practice, involving machines such as oil pipelines, water conservancy and hydropower, railway transportation, etc. The design principle is based on the measured pressure difference, that is, Δ 𝑃=𝜌𝑔Δ ℎ Δ P=ρ g Δ h. Due to the cylindrical shape of oil tanks, the cross-sectional area S remains constant. Therefore, the weight 𝐺=Δ 𝑃⋅𝑆=𝜌𝑔Δ ℎ⋅𝑆 G=Δ P ⋅ S=ρ g Δ h ⋅ S. Since S remains constant, the weight G is directly proportional to Δ 𝑃 Δ P. Therefore, as long as the Δ 𝑃 Δ P value is accurately detected, the actual liquid level can be calculated inversely proportional to the height Δ ℎ Δ h. When the temperature changes, although the volume of the oil expands or shrinks, and the actual liquid level rises or falls, the detected pressure remains unchanged. If the user needs to display the actual liquid level, medium temperature compensation can also be introduced to solve this problem.