Filter cartridge; components thereof; and methods

A method of reverse flow cleaning a filter cartridge;

• the method comprising:
• (a) providing at least one filter cartridge mounted in a tube sheet;
• the at least one filter cartridge including a media pack having a first flow face and an opposite second flow face;
• the media pack having:
• (i) a set of inlet flutes open at the first flow face to passage of air to be filtered therein;
• (ii) a set of outlet flutes open at the second flow face;
• (iii) the media pack being closed to flow of unfiltered air into the first flow face and then outwardly from the second flow face without filtering;
• the at least one filter cartridge being oriented to clean air as it flows from the dirty side, through the first flow face of the media pack and then through the second flow face of the media pack to the clean air side;
• and
• (b) directing a jet of air through the second flow face of the at least one filter cartridge to the first flow face using an air knife, the jet of air having a velocity of greater than 10,000 feet/minute.