Do Absolute, Gauge and Differential Pressure Sensors Measure Pressure Differently?

The sensing element of a pressure sensor, the part that turns the pressure into an electrical value, is independent of the type of pressure sensor and its sensing method. Environmental conditions where the sensor will be used and the media being measured will influence which sensing element should be used. This will have been considered by the pressure sensor manufacturer during the sensor’s development. When you research board-level pressure sensors for example, you’ll most likely find there’s a single data sheet covering all three sensors. The absolute, gauge and differential sensors share the same type of element and are simply provided in packages that differ in the number of ports provided for attaching hoses and pipes.

Are absolute, gauge and differential pressure sensors connected to circuit differently?

As with the sensor technology discussed above, the sensing method won’t determine how the pressure measurement is presented to the circuit or system. Pressure sensors can be broadly split into devices that are board-level, and those that are industrialized. Board-level sensors are typically designed to connect to other electronic circuitry, commonly in association with a micro controller that’s capable of evaluating its output. Such sensors range from the simple, requiring signal conditioning and amplification, through to the intelligent, which combine signal conditioning and deliver the measurement via a digital output. Most digital pressure sensors support I2C and SPI.

Industrial pressure sensors are designed to be integrated into industrial automation systems. Such systems utilize a programmable logic controller (PLC). These are designed to support the various analog interfaces supported today.

On the analog side, outputs range from a voltage signal to 4-20 mA current loops. The system will need to be programmed to understand how the pressure measured relates to the voltage or current the PLC sees.

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