| 摘要 |
<p>Gas normally flows from a conduit (106) through grooves (102) spaced around a slidable valve member (100) to flow through various passages (112, 68, 60) as both primary and secondary gas for the torch. If the electrode (72) is missing, the gas flow forces the valve member against a shoulder (92) and the gas flow is cut off. If any of the parts which have to be removed to change the electrode, namely gas distributor (40), tip (38) and cup (36), is missing, the electrode will not be held in place and can be pushed forward sufficiently for the valve to close, or for the electrode to block the plasma outlet (56) in the tip (38).</p> |
