Lab and fab shorthand for atmospheric pressure, about 1013 mbar or 760 Torr. A chamber at atmo has been vented and can be opened, a pump running from atmo is starting against full pressure, and a gauge that reads atmo on a pumped system is either telling you about a huge leak or has failed. Techs use it on the radio and in logbooks because the full phrase is too long when you are standing at the door.
PM chamber's at atmo and locked out, you can pull the lid.
Also heard as
- atm
- air
Related terms
Vent
To let gas back into an evacuated chamber, usually dry nitrogen, to bring it up to atmosphere.
Up to air
Said of a chamber that has been vented to atmospheric pressure and is open or ready to open.
Pump down
To evacuate a chamber from atmosphere to its working pressure, through roughing, crossover and high vacuum.