Suitable for pressure monitoring in sealed containers, such as vacuum coating equipment and closed cavities in the aerospace field, it can avoid the influence of atmospheric pressure changes on the measurement results. The accuracy requirements are usually higher than those of gauge pressure types.

• Constant reference: Unaffected by altitude, weather changes, or geographical location. The output signal for measuring the same absolute pressure is exactly the same whether today at sea level or tomorrow on a mountain.
• Direct measurement of absolute pressure: No need to convert from gauge pressure value plus estimated atmospheric pressure, eliminating errors caused by inaccurate atmospheric pressure estimation.
• High precision and stability: Due to the stable vacuum reference, it offers higher accuracy and repeatability in low ranges (especially near vacuum areas) compared to gauge pressure transmitters.
• Measurable down to zero: The measurement range can start from 0 psi(a) (absolute vacuum), which is impossible for gauge pressure transmitters (gauge pressure 0 corresponds to atmospheric pressure).

Absolute pressure transmitters are used in situations where the absolute pressure value of the medium or the system pressure is lower than or close to atmospheric pressure.

1. Vacuum system monitoring and control:
   • Semiconductor manufacturing (etching, deposition), vacuum coating, vacuum freeze drying, pharmaceutical distillation.
   • Measuring and monitoring different levels of vacuum (such as rough vacuum, high vacuum).
2. Meteorology and scientific research:
   • Atmospheric pressure measurement (barometer). The pressure in meteorological data must be absolute pressure.
3. Distillation and fractionation towers:
   • The pressure at the top and bottom of the tower is a key process parameter affecting component separation, and absolute pressure measurement must be used to ensure the accuracy of the process model.
4. Evaporators and crystallizers:
   • Operating under negative pressure (vacuum) to lower the boiling point and save energy. Absolute pressure transmitters are needed to precisely control the vacuum level.
5. Aviation and engine testing:
   • Measuring intake manifold pressure (MAP sensor), which is essentially an absolute pressure sensor, used to calculate the air-fuel ratio.
6. Processes requiring absolute pressure in calculations:
   • For example, when calculating gas density, mass flow rate (based on the ideal gas law, absolute pressure and temperature are required), or certain chemical reaction equilibrium constants, the input pressure must be absolute pressure.

An absolute pressure transmitter is a "precision reference instrument" in pressure measurement. It is not intended to replace a gauge pressure transmitter, but to meet the special and critical measurement requirements where the reference must be absolutely fixed or the pressure is lower than the atmospheric pressure.