In engineering applications, as well as in common everyday applications, most pressure changes are measured through gage pressure. This is the measurement of pressure based on the specific atmospheric pressure and is found in common items such as tire pressure gauges as well as in medical applications such as blood pressure cuffs.
However, there is also the need for very specific types of pressure measurements that are based on the use of the measurement against an absolute pressure, actually a perfect vacuum. These types of systems utilize an absolute pressure transducer to be able to provide those very specific types of measurements.
Use Of Absolute Pressure
While most people may not realize it, they are actually benefiting from the use of absolute pressure transducer readings in a variety of different applications. This is the measurement used in a barometer, and it is also the measurement that is used in altimeters in aircraft.
The benefits of the absolute pressure measurement over a gauge measurement is that the reference, the absolute vacuum, never changes. With the gauge pressure measurement, the reference point is the atmospheric pressure, which will change based on altitude, temperature and other factors that impact ambient pressure.
An absolute pressure sensor is also highly effective at determining if there is a leak in a sealed tank, where a constant, the absolute pressure, can determine even slight changes within the system.
How They Work
Within an absolute pressure transducer is actually a very small sealed vacuum which is known as the reference. This small sealed area will measure the difference between the inside of the sealed area, the perfect vacuum, and the exterior of the reference. This reference vacuum is shielded and protected within the system to provide accurate readings to the absolute pressure.
Sensitive electronic systems record the movement of sensors based on the change in the measured pressure against the vacuum. This output is usually as voltage, and it read by very sensitive electronic connections within the system. The transducer itself is calibrated to accurately measure this offset voltage against the vacuum. It is important to realize that the transducer is calibrated to reflect the variation from the perfect vacuum, as a true vacuum is not possible to sustain.
It will be important to choose a quality absolute pressure sensor or transducer for any application. These are more sensitive to changes in temperature, and it will be necessary to choose the right transducer for the specific application. With a reputable manufacturer, these transducers can provide highly accurate readings at the speed required based on the specific design and operating conditions.