Pressure Sensor

Pressure sensors are instruments used to measure and report the pressure of a fluid in an enclosure. Pressure sensors can be used to measure fuel pressure in a fuel line, oil pressure in an engine, barometric pressure at a weather station, water pressure in a pump system and many other kinds of pressure in many contexts. Pressure sensors are important safeguards to many kinds of equipment that involve pressurized fluid.

Because so many industries involve pressurized fluid in some way, pressure sensors are very important tools throughout industry. Wastewater treatment, petrochemical extraction and development, plastics processing and thermoforming, automotive manufacturing, aerospace products development and a long list of other industries rely on pressure sensors in some capacity to ensure the effectiveness and safety of their products and processes.

Pressure sensors are also often known as pressure transmitters; the two terms are synonymous, and they are descriptive of a pressure sensor’s purpose: to make monitoring technicians or systems aware of the extent to which an enclosure is pressurized. Some pressure sensors can also be pressure regulators, which both sense and control pressure levels, sometimes automatically and sometimes semi-automatically. Such sensors are designed to monitor changes in pressure and are often connected to safety devices that activate shut-off switches.

There are five types of pressure sensors: gauge, absolute, vacuum, differential, and sealed. Gauge sensors are calibrated to measure the pressure relative to atmospheric pressure at a given location. Atmospheric pressure at sea level is approximately 14.7 PSI. Because many, if not most, of the systems, equipment and processes that require the use of pressure sensors are only concerned with pressure levels relative to 14.7 PSI, gauge sensors are the most common of the five types of pressure sensors.

SITRANS P300 Hygienic Pressure Transmitter
SITRANS P300 Hygienic Pressure Transmitter – Siemens Process Instrumentation

Absolute sensors measure the pressure relative to 0 PSI, which is the complete absence of pressure. Since it is impossible to completely evacuate an enclosure (no prefect vacuums exist in nature either), it is more accurate and meaningful to say that absolute pressure sensors measure pressure without regard for ambient pressure conditions. Such pressure sensors are useful in conditions that are subject to frequent ambient pressure changes; scuba gear, for example, often employs absolute pressure sensors.

Vacuum sensors are used to measure pressure that is less than local atmospheric pressure, while differential sensors measure the difference between two or more pressure inputs in the unit. The last kind of sensor, sealed, is similar to the gauge sensor, except that it measures pressure relative to the pressure at sea level, 16.4 PSI.