Assertion: valve | /r/HasProperty | contrasted with many present valves
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Source sentences:
text: Likewise, inorder to provide for versatility in use, it is desirablethat the same valve be capable of either normally open of normally closed operation and be easily convertible from one to' the other by simple means, as contrasted with many present valves wherein two completely diflerent valves are required for these two'types of service.