Absolute Pressure Calculation
Calculate absolute pressure, gauge pressure, or atmospheric pressure instantly using the pressure formula calculator.
Calculator
Pressure is the force per unit area applied to any object in a direction perpendicular to the surface.
Pressure is defined as the normal force per unit area of a surface.
What is Absolute Pressure?
Absolute pressure is the total pressure measured relative to a perfect vacuum. It is equal to the sum of gauge pressure and atmospheric pressure.
Formula
| Absolute Pressure: Pa | Pg + Pat |
|---|---|
| Gauge Pressure: Pg | Pa - Pat |
| Atmospheric Pressure: Pat | Pa - Pg |
where,
- Pa = Absolute pressure
- Pg = Gauge pressure
- Pat = Atmospheric pressure
Types, definition and Formula:
| Pressure Type | Definition | Formula |
|---|---|---|
| Absolute Pressure (Pa) | The absolute pressure is the pressure of having no matter inside a space or perfect vacuum. The measurement of barometric pressure is the example of an absolute referenced pressure. |
Pa = Pg + Pat |
| Gauge Pressure (Pg) | The gauge pressure is measured in relation to ambient atmospheric pressure. The changes in atmospheric pressure is due to weather conditions. The gauge pressure higher than ambient pressure is referred to as positive pressure and the gauge pressure is lower than atmospheric pressure referred to as negative or vacuum gauge pressure. |
Pg = Pa - Pat |
| Atmospheric Pressure (Pat) | Because of unequal solar heating over the earth by sun, the temperatures varies over the entire globe. Air at the equator is much warmer than at poles. Therefore heavier air sinks toward the equator and warm (light) air rises and get spread towards the pole. The atmospheric pressure relate to daily weather patterns. The barometer is used to measure atmospheric pressure. |
Pat = Pa - Pg |
Difference between atmospheric pressure and gauge pressure
The atmospheric pressure is a measure of absolute pressure and is due to the weight of the air molecules above a certain height relative to sea level.
It is increasing with decreasing altitude and decreasing with increasing altitude.
The Gauge pressure is the additional pressure in a system relative to atmospheric pressure.
Solved Example
If gauge pressure is 50 kPa and atmospheric pressure is 101.3 kPa, find the absolute pressure.
P𝑎 = 50 + 101.3 = 151.3 𝑘𝑃𝑎
Therefore, the absolute pressure is 151.3 kP𝑎
.Frequently Asked Questions
What is the formula for absolute pressure?
Absolute pressure formula is: Absolute Pressure = Gauge Pressure + Atmospheric Pressure.
What is gauge pressure?
Gauge pressure is pressure measured relative to atmospheric pressure.
Can gauge pressure be negative?
Yes. Negative gauge pressure indicates vacuum pressure.