Units of Pressure
Units of Pressure
Pressure is a fundamental concept in physics, defined as the force applied per unit area. It is a critical parameter in both scientific and everyday contexts, influencing everything from weather patterns to the functionality of vehicle tires. To measure pressure, several units are utilized, each tailored to specific applications in science, industry, and engineering.
What are Units of Pressure?
SI Unit of Pressure
The pascal is defined as one newton per square meter (N/m²). This unit provides a direct measure of the force exerted over a specific area, making it fundamental for precise calculations in physics and engineering.
CGS Unit of Pressure
The barye is defined as one dyne per square centimeter (dyn/cm²). A dyne is the CGS unit of force, and it measures the force that would give a mass of one gram an acceleration of one centimeter per second squared.
List of Pressure Units
| Unit | Symbol |
|---|---|
| Pascal | Pa |
| Bar | bar |
| Atmosphere | atm |
| Torr | Torr |
| Pound per square inch | psi |
| Barye | Ba |
Pascal (Pa)
The Pascal is the SI unit of pressure named after the French mathematician, physicist, and inventor Blaise Pascal. It measures the force of one newton per square meter. It is widely used in science and engineering to quantify internal pressure, stress, Young’s modulus, and tensile strength.
Bar
The bar is a metric unit of pressure, but not part of the International System of Units (SI). It is closely aligned with the atmospheric pressure of Earth and is commonly used in meteorology, oceanography, and related fields.
Atmosphere (atm)
The atmosphere is a unit of pressure defined as being equal to the average atmospheric pressure on Earth at sea level. It is commonly used in various applications including meteorology and aviation.
Torr
1 Torr ≈ 133.322 Pa
Named after Evangelista Torricelli, an Italian physicist and mathematician, the Torr is a unit of pressure based on an earlier unit known as the millimeter of mercury (mmHg). It is primarily used in vacuum measurements.
Pound per square inch (psi)
1 psi = 6,894.76 Pa
The pound per square inch is a unit of pressure widely used in the United States and other countries still utilizing imperial standards. It measures the pressure resulting from a force of one pound-force applied to an area of one square inch.
Barye (Ba)
The Barye is the CGS unit of pressure. It is defined as one dyne per square centimeter. This unit is not widely used today but is still referenced in some scientific literature, particularly in fields related to physics.
Conversion of Pressure Units
Here’s a table format for pressure conversion between commonly used units of pressure: Pascal (Pa), Bar, Atmosphere (atm), and Pound per square inch (psi). The values provided are conversions from the unit in the left column to the units in the top row:
| Unit | Pascal (Pa) | Bar | Atmosphere (atm) | Pound per square inch (psi) |
|---|---|---|---|---|
| Pascal (Pa) | 1 | 0.00001 | 0.00000987 | 0.000145 |
| Bar | 100000 | 1 | 0.98692 | 14.5038 |
| Atmosphere (atm) | 101325 | 1.01325 | 1 | 14.696 |
| Pound per square inch (psi) | 6894.76 | 0.06895 | 0.068046 | 1 |
Pascal to Bar
- Conversion: 1 bar = 100,000 pascals.
- Example: To convert 500,000 pascals to bars, divide by 100,000.500,000 Pa / 100,000 = 5 bar
Pascal to Atmosphere
- Conversion: 1 atmosphere = 101,325 pascals.
- Example: To convert 202,650 pascals to atmospheres, divide by 101,325.202,650 Pa / 101,325 ≈ 2 atm
Pascal to Pound per square inch (psi)
- Conversion: 1 psi = 6,894.76 pascals.
- Example: To convert 34,474 pascals to psi, divide by 6,894.76.34,474 Pa / 6,894.76 ≈ 5 psi
Bar to Pascal
- Conversion: 1 pascal = 0.00001 bars.
- Example: To convert 3 bars to pascals, multiply by 100,000.3 bar × 100,000 = 300,000 Pa
Bar to Atmosphere
- Conversion: 1 atmosphere ≈ 1.01325 bars.
- Example: To convert 2 bars to atmospheres, divide by 1.01325.2 bar / 1.01325 ≈ 1.975 atm
Bar to Pound per square inch (psi)
- Conversion: 1 psi ≈ 0.06895 bars.
- Example: To convert 4 bars to psi, divide by 0.06895.4 bar / 0.06895 ≈ 58.02 psi
Atmosphere to Pascal
- Conversion: 1 pascal ≈ 0.00000987 atmospheres
- Example: To convert 3 atmospheres to pascals, multiply by 101,325.3 atm × 101,325 = 303,975 Pa
Atmosphere to Bar
- Conversion: 1 bar ≈ 0.98692 atmospheres.
- Example: To convert 5 atmospheres to bars, multiply by 0.98692.5 atm × 0.98692 ≈ 4.93 bar
Atmosphere to Pound per square inch (psi)
- Conversion: 1 psi ≈ 0.068046 atmospheres.
- Example: To convert 2 atmospheres to psi, divide by 0.068046.2 atm / 0.068046 ≈ 29.39 psi
Pound per square inch to Pascal
- Conversion: 1 pascal ≈ 0.000145 psi.
- Example: To convert 6 psi to pascals, multiply by 6,894.76.6 psi × 6,894.76 = 41,368.56 Pa
Pound per square inch to Bar
- Conversion: 1 bar ≈ 14.5038 psi.
- Example: To convert 10 psi to bars, divide by 14.5038.10 psi / 14.5038 ≈ 0.69 bar
Pound per square inch to Atmosphere
- Conversion: 1 atmosphere ≈ 14.696 psi.
- Example: To convert 15 psi to atmospheres, divide by 14.696.15 psi / 14.696 ≈ 1.02 atm
FAQ’S
What two units are used to measure air pressure?
Atmospheres (atm) and bars commonly measure air pressure, providing crucial data for meteorological studies and forecasting. These units effectively capture variations in atmospheric conditions.
What is the smallest unit of pressure?
The smallest unit of pressure is the barye, utilized primarily in the CGS (centimeter-gram-second) system, effectively measuring minute pressures.
What is the imperial unit of pressure?
The imperial unit of pressure is the pound per square inch (psi), which technicians and engineers frequently use across various industries.
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