A thermal conductivity gauge whose tube is designed so that, above a few millibar, natural convection carries heat away from the sensor, extending the useful range up to atmospheric pressure. It has to be mounted in the orientation the maker specifies, usually with its axis horizontal, because convection depends on gravity. Calibrated for nitrogen, it reads far too low in argon near atmosphere, so a backfill controlled by one can over-pressurize a chamber.
Don't backfill argon off the convection gauge, it reads way low and you'll over-pressure the chamber.
Also heard as
- Convectron
- convection Pirani
- convection-enhanced Pirani
Related terms
Pirani gauge
Thermal conductivity gauge that reads pressure from how quickly gas carries heat away from a hot wire.
Gas correction factor
Multiplier that converts a gauge reading calibrated for nitrogen into the true pressure of another gas.
Backfill
To fill an evacuated chamber with a chosen gas, often to a set pressure, rather than with room air.
Vent
To let gas back into an evacuated chamber, usually dry nitrogen, to bring it up to atmosphere.