| 摘要 |
<p>A diffuser is defined in part by a porous member 13 and the passage whereby gas under pressure can flow into an enclosure includes a non-return valve 24, 25 permitting gas under pressure to flow into the enclosure but preventing a reverse flow of liquid, in a fault situation, back into the gas supply pipe. In another aspect the invention resides in a diffuser for attachment to a gas supply pipe, the diffuser including a hollow unit defined by a porous member 13 and a base plate 11, the two being secured together and being sealed at their periphery. The sealed unit is provided with coupling means for securing it to a gas supply pipe. <IMAGE></p> |
