Lab phrase for a system that has been vented and sits at atmosphere, as in the chamber is up to air, or let it up to air. It tells everyone that the pumps are valved off, the vacuum is gone and the door can be opened. Time spent up to air means water soaking into the walls, so crews log how long a chamber was open when they predict the next pump-down.
Chamber's been up to air since Friday, so expect a slow pump-down and plan on a bake.
Also heard as
- let up to air
- at air
Related terms
Vent
To let gas back into an evacuated chamber, usually dry nitrogen, to bring it up to atmosphere.
Atmo
Shop clipping of atmospheric pressure, used for a chamber that is vented and open to air.
Wet
Said of a chamber whose walls still hold adsorbed water, so it pumps down slowly and stalls high.
Pump down
To evacuate a chamber from atmosphere to its working pressure, through roughing, crossover and high vacuum.