| 摘要 |
<p>For injecting substances into a liquid e.g. molten metal, a nozzle block (21) is mounted in the wall of a vessel (13) containing the liquid. Initially, an injection passage (11) extending through the block is closed by a plug (22) to prevent ingress of liquid, and only when injection is to commence, is the plug (22) thrust aside by a delivery pipe (24) movable in the passage (11), the pipe (24) forming part of an injection lance assembly. The positions of the lance assembly before and after injection are determined by a safety stop arrangement for example comprising a detent in the form of a spring-loaded plunger (60) housed in a fixed part (32) of the apparatus; the plunger coacts with front and rear ramps (65, 66) of an abutment (64) which is fast with part (25) of the lance assembly, to govern the positions of the lance assembly before and after injection.</p> |
