Understanding technical atmospheres to centimeters of mercury Conversion
A technical atmosphere equals one kilogram-force per square centimeter, or 98,066.5 pascals. A centimeter of mercury (cmHg) is the pressure exerted by a 1-centimeter column of mercury at standard conditions, about 1,333.22 pascals. This conversion appears in barometry and vacuum work, where mercury-column readings are compared to metric pressure ratings.
Conversion Formula
To convert technical atmospheres to centimeters of mercury, multiply by this factor:
Step-by-Step Example
Convert 25 technical atmospheres to centimeters of mercury.
How to Convert technical atmospheres to centimeters of mercury
Convert technical atmospheres to centimeters of mercury in one step.
- Take the pressure: Begin with the technical atmosphere value, for example 25.
- Multiply by the factor: Use 73.5559 cmHg per technical atmosphere.
- Report the result: 25 at \times 73.5559 = 1838.90 cmHg.
technical atmospheres to centimeters of mercury conversion table
| technical atmospheres (at) | centimeters of mercury (cmHg) |
|---|---|
| 0 | 0 |
| 1 | 73.55591 |
| 2 | 147.1118 |
| 3 | 220.6677 |
| 4 | 294.2237 |
| 5 | 367.7796 |
| 6 | 441.3355 |
| 7 | 514.8914 |
| 8 | 588.4473 |
| 9 | 662.0032 |
| 10 | 735.5591 |
| 15 | 1103.339 |
| 20 | 1471.118 |
| 25 | 1838.898 |
| 30 | 2206.677 |
| 40 | 2942.237 |
| 50 | 3677.796 |
| 60 | 4413.355 |
| 70 | 5148.914 |
| 80 | 5884.473 |
| 90 | 6620.032 |
| 100 | 7355.591 |
| 150 | 11033.39 |
| 200 | 14711.18 |
| 250 | 18388.98 |
| 300 | 22066.77 |
| 400 | 29422.37 |
| 500 | 36777.96 |
| 600 | 44133.55 |
| 700 | 51489.14 |
| 800 | 58844.73 |
| 900 | 66200.32 |
| 1000 | 73555.91 |
| 2000 | 147111.8 |
| 3000 | 220667.7 |
| 4000 | 294223.7 |
| 5000 | 367779.6 |
| 10000 | 735559.1 |
| 25000 | 1838898 |
| 50000 | 3677796 |
| 100000 | 7355591 |
| 250000 | 18388980 |
| 500000 | 36777960 |
| 1000000 | 73555910 |
What is the technical atmosphere?
The technical atmosphere (at) is a non-SI unit of pressure equal to one kilogram-force per square centimeter. It was widely used in engineering, especially in Europe, before the pascal became standard.
Definition
The technical atmosphere is defined as the pressure of one kilogram-force acting on one square centimeter:
This equals exactly 1 kgf/cm² (98,066.5 Pa), because standard gravity is 9.80665 m/s². It is close to, but distinct from, the standard atmosphere (atm = 101,325 Pa) and the bar (100,000 Pa).
Origin and History
The technical atmosphere arose from the gravitational metric system of units, which used the kilogram-force rather than the newton. Expressing pressure as kilogram-force per square centimeter was intuitive for engineers weighing loads, and the unit became common in mechanical and hydraulic engineering, boilers, and pneumatics through much of the 20th century.
Law and Notable Facts
The technical atmosphere is not part of the SI and its use is discouraged in favor of the pascal or bar. It is easily confused with the standard atmosphere; the two differ by about 3.3%. Gauge and absolute variants were often written "atü" (gauge) and "ata" (absolute) in German-language engineering.
Real-World Examples and Conversions
- 1 at = 1 kgf/cm² = 98.0665 kPa ≈ 0.9678 atm.
- 1 at ≈ 14.223 psi, close to but slightly below the 14.696 psi of one standard atmosphere.
- A pressure of 10 at (about 981 kPa) is a common rating benchmark for industrial hydraulic components.
- 1 at ≈ 0.980665 bar, so the bar and technical atmosphere differ by under 2%.
What is the centimeter of mercury?
The centimeter of mercury (cmHg) is a unit of pressure equal to the pressure exerted by a one-centimeter-high column of mercury under standard conditions. It is a scaled-up form of the millimeter of mercury (torr) used in some scientific and industrial settings.
Definition
The conventional centimeter of mercury is based on a 1 cm column of mercury with a density of 13,595.1 kg/m³ under standard gravity (9.80665 m/s²):
Exactly, 1 cmHg = 1333.22387415 Pa, which is ten times the millimeter of mercury (1 mmHg ≈ 133.322 Pa). This equals 10 torr under the conventional definition.
Origin and History
The unit descends directly from Torricelli's mercury barometer of 1643, where atmospheric pressure was read as the height of a mercury column. Mercury's high density makes the column compact and easy to read. The conventional value fixes mercury's density (its value at 0 °C) and standard gravity so the unit is independent of temperature and location.
Law and Notable Facts
The centimeter of mercury is not an SI unit; the SI unit of pressure is the pascal. It relates to the standard atmosphere as 1 atm = 76 cmHg exactly (by the historical 760 mmHg definition). The millimeter of mercury (mmHg), essentially identical to the torr, remains standard in medicine for blood pressure.
Real-World Examples and Conversions
- 1 cmHg = 10 mmHg (10 torr) ≈ 1.33322 kPa.
- One standard atmosphere equals exactly 76 cmHg.
- A blood pressure of 120/80 mmHg corresponds to 12/8 cmHg.
- A vacuum of 5 cmHg absolute is about 6.7 kPa, roughly 93% below atmospheric pressure.
Frequently Asked Questions
How many centimeters of mercury equal one technical atmosphere?
One technical atmosphere equals about 73.5559 centimeters of mercury.
How many technical atmospheres are in a cmHg?
One centimeter of mercury is about 0.0135951 technical atmospheres.
What is a centimeter of mercury?
It is the pressure from a 1-cm mercury column, roughly 1,333 pascals, used in barometers and vacuum gauges.
Where is this conversion used?
It is common in laboratory vacuum systems and meteorology where mercury readings meet metric pressure units.
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Complete technical atmospheres conversion table
| Unit | Result |
|---|---|
| pascals (Pa) | 98066.5 Pa |
| kilopascals (kPa) | 98.0665 kPa |
| megapascals (MPa) | 0.0980665 MPa |
| hectopascals (hPa) | 980.665 hPa |
| millibar (mbar) | 980.665 mbar |
| bar (bar) | 0.980665 bar |
| torr (torr) | 735.5592 torr |
| meters of water @ 4°C (mH2O) | 10 mH2O |
| millimeters of mercury (mmHg) | 735.5591 mmHg |
| standard atmospheres (atm) | 0.9678411 atm |
| centimeters of water (cmH2O) | 1000 cmH2O |
| centimeters of mercury (cmHg) | 73.55591 cmHg |
| pounds per square inch (psi) | 14.22334 psi |
| kilopound per square inch (ksi) | 0.01422334 ksi |
| Inches of mercury (inHg) | 28.95902 inHg |