A flange plate with no opening, made in every flange family (KF, ISO and CF), that closes a port with nothing mounted on it. Blanks cap spare ports, isolate sections during leak hunting and let a pump's ultimate pressure be measured with its inlet sealed. Putting a blank on a suspect pump and checking what it pulls is the quickest way to separate a pump problem from a chamber problem.
Throw a KF40 blank on the scroll inlet and see what it pulls on its own, then we'll know if it's the pump.
Also heard as
- blank-off
- blank flange
- blind flange
Related terms
Ultimate pressure
The lowest pressure a pump can reach on a sealed, clean test dome, as stated on its data sheet.
CF flange
All-metal flange that seals by biting knife edges into a soft copper gasket, the standard joint for UHV.
KF flange
Quick-release clamp flange with a centring ring and O-ring, the standard small fitting for rough and high vacuum.
Chase a leak
To hunt down a leak of unknown location joint by joint, often over hours, until the source is pinned down.