The symbol at stands for technical atmospheres, a non-Si, outdated-metric unit of pressure. 1 technical atmosphere is defined as 1 kilogram-force per square centimeter.
The SI unit of force is newtons (N), so you may not be sure what a kilogram-force (kgf) is. That is the force created by 1 kilogram of mass by the earth’s gravity. In other words. 1 kgf is 9.8 N. The technical atmosphere is that force, per square centimeter.
1 at = 98066.5 Pa.
The technical atmosphere (at) is roughly equal to the standard atmosphere (atm) because of the coincidence of units. I’ve heard that some European watches still use this unit, but otherwise the at is outdated and rarely used today.
If you are using a machine that uses this unit of pressure, it’s time for an upgrade 🙂
|1 at =||98,070 Pa||0.968 atm|
This article was a definition of at. If you are interested in all the different, strange units that are used to measure pressure, I wrote an entire article explaining what each unit is, and how to convert between them. Or, if there is a unit you are especially interested in, you can check out one of the other unit definitions I’ve written.
Other Pressure Measurements:
mbar or bar
psi or ksi