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Show Prevents Gas Escaping. The well-known principle of expansion expan-sion under heat and contraction under ccld has been utilized by Louis P". Ducker, of Boston, Mass., in designing design-ing the automatic cut-off for gas burners. burn-ers. He says this burner will automatically auto-matically close the valve to prevent leakage in case the flame is accidentally accident-ally extinguished or the flow of gas is interrupted for a short interval. To accomplish this end a metallic collar Is attached to the burner near the tip, Automatic Cut-Off for Gas Burners. one end being connected wita a vertical verti-cal rod, leading downward to a pivoted block on the jet arm. On top of this arm is placed a sliding bolt, which interferes in-terferes with both the pivoted block and a dog on the valve key when these two members are in a certain position. The bolt is normally forced toward the tip by a coiled spring, but it is obvious that when the block is in the way the rod Is held in position to engage the dog on the cut-off key. This can only be done by expanding the collar sufficiently suffi-ciently under the heat of the flame to maintain the block in line with the end of the rod, and when the flame is extinguished the contraction of the collar turns the block to one side and allows the rod to draw back from the dog at the opposite end of the jet arm. As the key has a spring to close It when the dog is released, it is plain to be seen that this action will immediately im-mediately take place, thus preventing further How from the jot. |