Up to 240°C also industrial bag-filters are in use. A lot of filter bags, stabilized with gabions are positioned in mostly cases vertically. This filters are cleaned by a back flushed compressed air ( jet-pulse system) either with diagnosis of the difference pressure or cyclic with a timer. Material at the candles will fall down and is collected by a spiral conveyor or a rotary star valve. In many cases this material can be reused in the process. The bags are consumables. Their lifetime, depending on the waste, is between a few days to a lot of years. Their material is either organic (cotton) or at higher temperature level < 240°C also in PTFE.