To admit gas into a vacuum system until it reaches atmospheric pressure so it can be opened. Good practice vents with dry nitrogen rather than room air, because nitrogen leaves far less water on the walls and the next pump-down is faster. Venting too fast stirs up particles and can damage gauges, filters and spinning turbos, so tools use a soft vent through a small orifice before opening a larger valve.
Vent the load lock with nitrogen, not house air, we're already chasing water on this tool.
Keep a small nitrogen purge flowing while the chamber is open; it stops humid room air rolling in and shortens the next pump-down.
Also heard as
- vent up
- let up
- bring up to air
Related terms
Up to air
Said of a chamber that has been vented to atmospheric pressure and is open or ready to open.
Backfill
To fill an evacuated chamber with a chosen gas, often to a set pressure, rather than with room air.
Soft pump
Slow, throttled roughing from atmosphere that avoids stirring up particles and condensing moisture.
Wet
Said of a chamber whose walls still hold adsorbed water, so it pumps down slowly and stalls high.
Atmo
Shop clipping of atmospheric pressure, used for a chamber that is vented and open to air.