Absolute pressure

Definition

Absolute pressure is the total pressure exerted on a system, including atmospheric pressure. It is measured relative to a perfect vacuum.

5 Must Know Facts For Your Next Test

1. Absolute pressure is calculated as the sum of gauge pressure and atmospheric pressure.
2. The standard unit of absolute pressure in the International System of Units (SI) is the pascal (Pa).
3. Absolute pressure can never be negative because it includes atmospheric pressure, which is always positive.
4. Common instruments used to measure absolute pressure include barometers and specific types of manometers.
5. In equations, absolute pressure is often denoted by $P_{abs}$.

Review Questions

• How do you calculate absolute pressure from gauge pressure?
• What type of instruments are commonly used to measure absolute pressure?
• Why can absolute pressure never be negative?

Related terms

Gauge Pressure:

The difference between absolute pressure and atmospheric pressure, often measured with a gauge that reads zero at atmospheric conditions.

Atmospheric Pressure:

The force per unit area exerted against a surface by the weight of the air above that surface in the Earth's atmosphere.

$\text{Pascal (Pa)}$: $\text{The SI unit for measuring pressure, equal to one newton per square meter (N/m}^2\text{).}$