Anti-leakage or anti-return valves

Full Title

Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions > Safety devices specially adapted for filtration (preventing or minimising fires or explosions A62C); Devices for indicating clogging (incorporated in a throw-away filter B01D27/10) > Anti-leakage or anti-return valves