Absolute Pressure Transmitter , Double Chamber Differential Pressure Transmitter
Double Chamber Structure Can Measure Absolute Pressure And Absolute Pressure Differential Pressure Transmitter
An absolute pressure differential transmitter is essentially a differential pressure transmitter, but its low-pressure side (reference end) is permanently sealed and evacuated to a high vacuum, forming an absolute pressure reference benchmark.
- Core Sensor: Utilizes piezoresistive, capacitive, or resonant sensors. The sensor diaphragm senses the pressure on both the H side and the L side.
- Key Process: During manufacturing, the reference cavity on the low-pressure side (L) is evacuated and permanently sealed. This vacuum cavity serves as the "absolute zero pressure" reference point.
- Measurement Process: The process pressure acts on the high-pressure side (H) diaphragm and is compared with the vacuum reference on the low-pressure side (L). The sensor directly outputs a signal proportional to the absolute pressure at the H side.
| Characteristics | Absolute pressure differential pressure transmitter | Ordinary absolute pressure transmitter | Ordinary differential pressure transmitter |
|---|---|---|---|
| Reference basis | The low-pressure side is absolute vacuum | The sensor reference cavity is absolute vacuum | The low-pressure side is open to the atmosphere (gauge pressure) or another process pressure |
| Measurement output | The absolute pressure of the high-pressure side (P_H abs) | The absolute pressure at the connection end (P abs) | The pressure difference between the high and low-pressure sides (P_H - P_L) |
| Essence | Special configuration differential pressure transmitter | Dedicated design absolute pressure instrument | General differential pressure instrument |
| State of the low-pressure side | Permanently sealed vacuum | Integral sealed vacuum | Open or connectable |
| Can it measure differential pressure | No (unless the seal is broken) | No | Yes |
| Main applications | Negative pressure systems requiring absolute pressure, high static pressure absolute pressure measurement | General absolute pressure measurement (vacuum, meteorology, calculation) | Flow, level, general differential pressure |
| Flexibility | Medium (fixed as absolute pressure, but the hardware is differential pressure) | Low (dedicated) | High (can be connected as gauge pressure, absolute pressure, differential pressure) |
The absolute pressure differential transmitter is a functionally specific but extremely useful "variant" in the family of differential pressure transmitters. It ingeniously utilizes the dual-chamber structure of the differential pressure transmitter by "fixing" one end at absolute zero, thereby achieving the function of absolute pressure measurement.
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