| 摘要 |
A plasma torch is provided having a movable member carrying an electrode and movable along a tubular member bore having a nozzle at one end. A piston member engaged with the movable member moves the electrode between inoperable and operable positions within the bore, the movable member being biased outwardly of the one end of the bore. A first sealing member engaged with the piston member allows a fluid flow into the bore to act on the piston member to move the electrode to the operable position when the nozzle/electrode is engaged with the tubular member. A second sealing member, engaged with the bore, engages the piston member when the nozzle/electrode is removed. The fluid flow enters the bore between the sealing members, the second sealing member thus preventing torch operation when the nozzle/electrode is removed by preventing the fluid flow from acting on the piston member.
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