Automatic Shut-Off Device for Extraction Systems
Automatic shut-off for extraction systems: A sensor-based control that runs extraction fans only during active welding current. Optimizes energy consumption and reduces filter wear.
Physico-chemical mechanism of action
The unit detects whether welding is in progress and switches the extraction on accordingly. The usual setup is a current sensor that sits as a clamp around the welding cable and picks up the magnetic field of the flowing welding current. When the arc strikes, the fan starts. If the current stops for a while, a run-on time follows, then shutdown. The run-on time isn't a luxury, because after the last pass the fume is still hanging in the hood.
Metallurgical relevance & welding risks
Without this control, the system just runs: power, filter life, and noise all wasted. On the flip side, if extraction is too strong or too close to the joint, it pulls the shielding gas away from the weld pool, and you get porosity in the weld. Either way, it's a matter of setup, not the equipment.
Workshop practice & instructions
Put the sensor around the welding cable, not the power cord. Set the trigger threshold so it reliably trips at the lowest welding current you actually use, otherwise the extraction won't come on when tacking. The airflow rate and run-on time are set by the extraction manufacturer for the particular capture hood—those values go into the unit, not into gut feeling. After install, test at the weakest working point: when the arc strikes, the hood must visibly pull.