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US3339791A
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Emergency venting manhole cover
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US3302658A
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Mechanical vent for tanks
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US3257093A
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Gusher valve
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US3209938A
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Quick opening pressure manhole
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US3179285A
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Manhole fusible joint and improved gasket
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US3065949A
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Chemical emergency valve
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US3029833A
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Bottom loading emergency valve
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US2844121A
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Liquid volume-level indicator
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US2508231A
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Fusible and frangible plug for safety systems
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US2596891A
|
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Expanding plug for gate valves
|
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US2600977A
|
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Emergency valve system
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US2589346A
|
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Emergency valve
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US2529329A
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Safety tank closure
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US2557177A
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Valve structure
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