The filter is provided with polyester needle-felt envelopes, stretched and sealed around rectangular frames, which can be changed through an inspection door at the front of the filter. Very little space is required per m2 of filter area.
过滤器有涤纶针刺毡的信封，伸在矩形框密封，可通过检查门在前面的过滤器的。很小的空间是每平方米过滤面积要求。
