| 摘要 |
PROBLEM TO BE SOLVED: To provide a safety apparatus for gas welding and fusion cutting structured so that the flow passage can be shut off when the burning gas makes counterflow, assuring certain operation even if the counterflow is at a low pressure. SOLUTION: A cylindrical body 1 having a flow passage leading from the primary side to the secondary side is furnished with a spindle 4 to open and close the passage. The spindle 4 is energized by a spring 14 toward the secondary side and has a spindle body 5 and a shutoff spindle 6. A secondary side body 3 connected with the cylindrical body 1 is furnished internally with a secondary side spindle 35 in such a way as mating with the shutoff spindle 6. The secondary side spindle 35 is energized by a balance spring 39 having a some weaker spring force than the spindle spring 14 so as to move the shutoff spindle 6 toward the primary side. When a counterflow of the burning gas is generated from the secondary side to the primary side, the flow passage can be shut by actuating the spindle if there is a pressure equal to or higher than the differential pressure between the spindle spring and the balance spring even if the counterflow is at a low pressure. COPYRIGHT: (C)2005,JPO&NCIPI
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