Pressure Sensors
Besides sensing pressure in liquid and gas flow, pressure sensors provide altitude testing for the aerospace industry, flow sensing, level depth sensing in submerged vessels like submarines and leak testing, which senses the decrease in pressure of a system that uses liquid or gas. Pressure sensors are generally very small pieces of equipment, a lot like
miniature load cells, sometimes as small as a cubic inch. Microelectromechanical systems, however, use pressure sensors hundreds of times smaller. These are just a few examples of the applications and industries that utilize this handy
load cell. This mechanism usually uses
strain gauges, metal alloys, semiconductors or film resistors to conduct electricity as the liquid or gas passes them and the pressure deforms the material of the pressure sensor. The amazing thing about all of these conductive materials is they are so sensitive that the slightest shift in the flow of fluid or gas will be noted and watched.
There are five main types of pressure sensors used today. The most common is the gauge sensor, which is calibrated and measures pressure while taking into account atmospheric pressure. Absolute pressure sensors measure for pressure relative to a perfect vacuum, while vacuum sensors are used when the pressure being measured is lower than localized atmospheric pressure. Differential sensors measures the differences between two or more pressures introduced as inputs to the sensing unit and are used to measure flow in pressurized vessels. Sealed pressure sensors measure pressure relative to seal level pressure. Pressure sensors also receive and display data in different ways. Their results are displayed in analog form, switch and alarm outputs, digital or video displays or AM/FM signals. Because pressure sensors are so delicate, there is often a medium between it and the fluid or gas it is measuring. This can be a metallic diaphragm or a fluid chamber, used to protect the sensor without affecting the precise and accurate results it is able to deliver.
