Due to different structures, the capsule pressure sensor can be divided into measuring absolute pressure, relative pressure with respect to the atmosphere and pressure difference. When measuring absolute pressure, the capsule pressure sensor has its own vacuum reference pressure. The measured pressure has nothing to do with atmospheric pressure, but with vacuum. The relative pressure with respect to the atmosphere is based on the atmospheric pressure, so the elastic membrane side of the sensor is always connected to the atmosphere.

Since atmospheric pressure is related to the height above the ground, the changes in the content of water vapor in the atmosphere during the four seasons and the changes in the contents of various gases that make up the atmosphere at different locations are all related to the height of the atmosphere. Therefore, the measured relative pressure is related to the above factors. In addition, the fluid pressure can also be introduced separately from both sides of the elastic membrane of the capsule pressure sensor, so that the pressure difference between different positions or fluids can be measured.