To stay at low pressure after being isolated from the pumps. Saying a chamber won't hold is the shop verdict that its pressure climbs fast when the valve closes, pointing to a leak, a wet chamber or a valve that passes. The quick version of a rate-of-rise test is to shut the valve and watch the gauge for a minute.
Rig won't hold vacuum for more than a minute, it's back to atmo in an hour, something's wide open.
Also heard as
- hold
Related terms
Rate of rise
Test that isolates a pumped chamber and tracks how fast the pressure climbs, to estimate leaks and outgassing.
Gross leak
Leak big enough to stop a system pumping down properly, or to be found without sensitive instruments.
Chase a leak
To hunt down a leak of unknown location joint by joint, often over hours, until the source is pinned down.
Leak check
To test a system or a joint for leaks, usually with a helium leak detector, after any break of vacuum.