Absolute Pressure is the total pressure exerted on a system, measured relative to a perfect vacuum. It includes both the atmospheric pressure and the gauge pressure within a system. Essentially, absolute pressure is the sum of the atmospheric pressure and any additional pressure exerted by a fluid or gas.
Key Points:
Definition:
Absolute pressure (P absolute) is given by:
where:
P gauge is the gauge pressure (the pressure measured relative to atmospheric pressure).
PatmosphericP_{atmospheric}Patmospheric is the atmospheric pressure.
Measurement Context:
Absolute pressure measures the total pressure exerted, including the pressure due to the weight of the atmosphere. It is the pressure relative to a perfect vacuum, which is considered the zero point for pressure.
Applications:
Scientific Research: Many scientific calculations and experiments require absolute pressure for accuracy, as it provides a reference point that is not affected by local atmospheric variations.
Engineering: Design and safety considerations often require knowing the absolute pressure to ensure systems function correctly under various conditions.
Atmospheric Studies: In meteorology and climatology, absolute pressure helps in studying weather patterns and atmospheric conditions.
Instruments:
Barometers: Used to measure atmospheric pressure, which is then added to gauge pressure to find absolute pressure.
Absolute Pressure Sensors: Specialized sensors that measure pressure directly relative to a vacuum.
Examples:
Vacuum Systems: In vacuum chambers, the absolute pressure is low because it is measured relative to a perfect vacuum. The gauge pressure in such systems would be negative.
Pressurized Containers: Inside a pressurized container, the absolute pressure is the sum of the container's gauge pressure and the atmospheric pressure outside.
In summary, absolute pressure is a comprehensive measure of pressure that includes all atmospheric and additional pressure, providing a complete picture of the pressure in a system relative to a perfect vacuum.