What Are Pressure Units?
Pressure is force per unit area. The SI base unit is the Pascal (Pa), equal to 1 Newton per square metre. Different fields use different units depending on the scale and tradition.
Common Pressure Units and Their Uses
- Pascal (Pa) / kPa / MPa: SI standard for science and engineering. 1 kPa = 1,000 Pa; 1 MPa = 1,000,000 Pa.
- Bar / mbar: Widely used in meteorology and industry. 1 bar = 100,000 Pa ≈ 1 atm. Weather forecasts use mbar (hectopascal).
- Atmosphere (atm): Standard atmospheric pressure at sea level; 1 atm = 101,325 Pa = 760 mmHg.
- PSI (lb/in²): Used in the US for tires, gas cylinders, and hydraulics. 1 PSI ≈ 6,895 Pa.
- mmHg (Torr): Medical standard for blood pressure and vacuum measurements. 1 mmHg = 133.322 Pa.
Practical Reference Values
Car tires: 2.0–2.5 bar (29–36 PSI). Sea level air: 1013 mbar. Recreational diving limit: 40 m (5 atm). Industrial steam lines: 6–16 bar.
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