A diffuser for dispersing gas into a body of liquid that may contain suspended solids. Under ordinary clogging conditions, the diffuser will remain operative over an indefinite period of time by reason of large gas outlet openings at the bottom of the gas plenum chamber. In addition, it can be employed...http://www.google.com.tw/patents/US4557879?utm_source=gb-gplus-share專利 US4557879 - Gas diffuser with indefinite life and mixed bubble size capacity
