Pressure Sensors Review

Electronics, Instrumentation & Electrical Database

Pressure Sensors Review

Pressure sensors, also called pressure transducers, are used to measure the force exerted within or onto a mechanical system. Most often the system requiring measurement utilizes a fluid to exert force. The pressure sensor converts the applied or measured force into a electrical or mechanical reading or output. Normally the pressure sensor senses a displacement on an element of the sensor and converts into a output. Pressure sensors which are electrical, may exhibit a change in electric resistance or output voltage, or provide a digital signal for processing. Mechanical pressure sensors utilize a displacement as a result of a membrane or similar mechanical device deflecting due to the applied pressure or force. In all cases the pressure sensor is calibrated by various means and will be provided with performance specifications.

The following are the types of fluid pressure measurements which a fluid pressure sensor may measure:

Absolute Pressure Sensor: This gage measures the pressure exerted within a vacuum relative to absolute zero pressure. When a full vacuum has been applied to a system, the sensor will read zero.

Gauge Pressure Sensor: These are the most common gauge types used within industry. Theses pressure sensors measure the differential pressure relative to atmospheric pressure. Common applications are automotive or bicycle pressure gauge. The measured pressure within the tire is that pressure applied within the tire above atmospheric pressure (14.7 psia).

Differential Pressure Sensor: This pressure sensor measures the pressure difference between two or more systems and outputs a reading equal to the difference of pressure between the two systems. When both system are at the identical pressure the reading will be zero. The systems may actually be at a elevated pressure relative to atmospheric or absolute pressure.

Vacuum Pressure Sensor: Vacuum pressure sensors are designed and calibrated to output a zero reading at atmospheric pressure. As the pressure within the system decreases towards absolute pressure the gauge output will change. Pressure due atmospheric forces is equal to approximately 14.7 psia or 100 kPa at sea level.

Barometric Pressure Sensor: Barometric Pressure Sensors are actually absolute pressure sensors. The output of the sensor is indicated or displayed in "inches of Mercury (Hg)". The ranges of measure are typically quite narrow when compared to other pressure sensor types. Measure range maybe limited to 25 to 32 inches-Hg.