What Is Technical Atmosphere (at)?
The technical atmosphere, written as at, is a unit used to measure pressure. It tells us how strongly a force presses on a surface. One technical atmosphere is almost the same as the air pressure we feel at sea level on Earth, but it is not exactly the same. Today it is mostly an old engineering unit and the pascal Pa is used instead in science.
Definition
Pressure is how much force acts on a certain area. The technical atmosphere is defined using force and area in this way:
- 1 technical atmosphere at is the pressure made by the weight of a 1 kilogram mass
- This force pushes on an area of 1 square centimeter
In modern SI units:
- 1 at = 98 066.5 pascals Pa
- This is about 98.07 kilopascals kPa
- It is a little less than normal air pressure at sea level, which is about 101.3 kPa
So a technical atmosphere is a unit that links old force ideas kilogram force with area square centimeter to get pressure.
History / Origin
The technical atmosphere was created in the early 1900s for engineers and technicians. At that time, many people used kilogram force and centimeters in work and teaching. They wanted a pressure unit that fit well with these everyday values.
The unit became common in some European countries, especially in Eastern Europe and the former Soviet Union. It was often used in mechanical engineering, hydraulics, and pneumatics to show working pressures in machines and pipes.
Later, the international system of units SI chose the pascal Pa as the standard pressure unit. Because of this, the technical atmosphere is now considered an old or non SI unit. It still appears in older books, drawings, and tools but new work is usually done in pascals, bar, or sometimes in standard atmosphere atm.
Symbol & Abbreviation
The technical atmosphere uses a short symbol so it is easy to write in tables and on devices.
- Name technical atmosphere
- Symbol at
- Type of quantity pressure
Careful, at is not the same as:
- atm which means standard atmosphere another pressure unit
- Pa which means pascal the SI pressure unit
Technical drawings, old gauges, or manuals may write pressure as 5 at or 20 at, always using lowercase letters.
Current Use Around the World
Today the technical atmosphere is rarely used in new designs, but it has not fully disappeared.
You may still see at in these cases:
- Older engineering books, tables, and charts
- Old pressure gauges on machines or compressors
- Hydraulic and pneumatic systems built many years ago
- Some documents from Russia and other Eastern European countries
Modern standards in most countries ask people to use the pascal Pa or sometimes the bar instead. When engineers meet a pressure in at, they usually convert it to kPa, bar, or atm so that everyone can compare values easily.
Example Conversions
Here are some useful approximate conversions for the technical atmosphere. These values are rounded to make them easier to remember.
- 1 at ≈ 98 066.5 Pa
- 1 at ≈ 98.07 kPa
- 1 at ≈ 0.9807 bar
- 1 at ≈ 0.9678 atm standard atmosphere
- 1 at ≈ 14.22 psi pounds per square inch
Example pressures:
- 2 at ≈ 196.1 kPa ≈ 1.96 bar
- 5 at ≈ 490.3 kPa ≈ 4.90 bar ≈ 71.1 psi
- 10 at ≈ 981 kPa ≈ 9.81 bar
Simple conversion rules you can use:
- To change at to kPa, multiply by about 98.07
- To change at to bar, multiply by about 0.981
- To change at to atm, multiply by about 0.968
- To change at to psi, multiply by about 14.22
Related Units
The technical atmosphere is one of several units used to describe pressure. Here are some closely related ones.
- Pascal Pa the official SI unit of pressure, 1 Pa is 1 newton per square meter
- Kilopascal kPa 1 kPa = 1000 Pa, often used for weather reports and engineering
- Standard atmosphere atm a unit based on average sea level air pressure, about 101.325 kPa
- Bar a convenient metric unit, 1 bar = 100 kPa, close to standard air pressure
- Kilogram force per square centimeter kgf per cm² this is another way to write the same thing as 1 at
- Pounds per square inch psi a pressure unit common in the United States and in car tire pressures
Knowing how at relates to these units helps you read both old and new technical information.
FAQs
Question Is the technical atmosphere an SI unit
Answer No, the technical atmosphere is not part of the SI system. The official SI unit for pressure is the pascal Pa. The technical atmosphere is an older, non SI unit.
Question Which is larger, 1 at or 1 atm
Answer 1 standard atmosphere atm is a little larger than 1 technical atmosphere at. In numbers, 1 atm is about 101.3 kPa and 1 at is about 98.1 kPa.
Question Why was the technical atmosphere created
Answer It was created to match the units that engineers once used every day, kilogram force and centimeters. This made pressure calculations easier before the SI system and the pascal became standard.
Question Where might I still see pressures written in at
Answer You may see at on older pressure gauges, in historic engineering books, or in old technical drawings, especially from Eastern Europe or the former Soviet Union.
Question How can I quickly convert from at to bar
Answer A simple rule is to multiply by about 0.98. For example, 5 at is about 5 × 0.98 which is 4.9 bar. For more exact work, use a calculator with the full factor 0.980665.
Question Is 1 at the same as 1 kgf per cm²
Answer Yes, by definition 1 technical atmosphere at is exactly equal to 1 kilogram force per square centimeter kgf per cm². They are just two names for the same pressure.
