Filter bags made of polyimide needle felt with oil and water repellent PTFE-based finish are intended for working temperatures above 200 ° C. The use of polyimide is usually the next step after PPS, where the resistance limits of the PPS are reached.
Polyimide is a material which retains outstanding filtration properties due to the unusual and irregular fiber structure. Filter bags from this polymer have a very high filtration efficiency without affecting the air permeability.
The oil and water repellent finish protects the filter bags against moisture and facilitates their regeneration. The PTFE content in the impregnation increases their resistance to acids, alkalis and hydrolysis.
If a suitable proportion of NOx in the exhaust gases is maintained, filter bags made of P.84 can be used without any problems for at least 24 months.