Filter life on fume extraction systems is tough to predict. Systems with a cleaning device will typically last between 6 to 12 months. For systems with no automatic cleaning process, it’s very dependent on the filter size, the welding wire used, base metal and the parameters of the welding machine. For instance, high vacuum systems without an automatic cleaning system can need filter replacement after as little as two spools of flux-cored wire. On LEV systems the filter is most of the time not monitored automatically, so there is no signal, whether the filter is full or not. How long the filter lasts depends on the duty cycle, the welding process, the material welded, etc. As a rough calculation you can say that if you’re using the LEV 3-4 hours a day the filter has to be changed one time per month. Regardless, it’s important to monitor the efficiency of the fume extraction system. If you find it is not adequate, the filter is one of the first things to check. Some systems have sensors or gauges built in that will activate when the differential pressure in the filter is too high, which lets you know you need to replace the filter.