Pressure sensors and transducers are  frequently composed of a small integrated circuit called a microchip attached to metal wires. Miniature pressure sensors can be less than a tenth of an inch in width so that they don't influence the pressure of the substance they are measuring. Other sensors are encased in stainless steel to withstand harsh environments and are combined with couplers or nozzles to determine the pressure of the fluid as it flows by. These devices are typically combined to form a SAFETY VALVES system with all the relevant information in one location. Measuring absolute pressure uses the same process; the difference is that the sensor measures the pressure as compared to the pressure of a perfect vacuum, which is 0 pounds per square inch (PSI). The absolute pressure of the atmosphere at sea level, for example, is ~14.7 PSI. Pressure transducers and sensors are widely used in many industries. Pressure sensors are used to regulate the flow rate of propane, fuel, water and other liquids. They can also expose leaks and determine altitude and depth.

Absolute pressure sensors are only one of the five main kinds of sensors. Gauge, vacuum, differential and sealed pressure sensors are used to measure different kinds of pressure. For example, gauge pressure sensors are calibrated to measure pressure relative to a given atmospheric pressure at a specific location. Pressure sensors, also known as pressure transmitters, and transducers have been used for over a century. Improvements in materials and technology have allowed them to become smaller, more durable and more accurate. The integrated circuit revolutionized electronics and absolute pressure sensors have come to rely on the tiny chips. Most have less than one percent for the margin of error, and temperature transducers provide readings within 1.5