Ventil

摘要

A valve in which durability of a sealing member made from an elastic material can be increased and sealing capability can be advantageously maintained over a wide range from a large differential pressure to a low differential pressure. A valve (100), in which a valve disc (1) and a valve seat (2) are brought into close contact via a sealing member (5) composed of an elastic material and provided at the valve disc (1) or valve seat (2), comprises a throttle section (30) defined by the shape of at least one of the valve disc (1) and valve seat (2). The throttle section (30) narrows a flow passage formed between the valve disc (1) and valve seat (2) and is provided near the sealing member (5). The flow passage narrowed by the throttle section (30) is so set that narrowing preferentially proceeds in the flow passage in close proximity to the sealing member (5) during the closing operation of the valve disc (1).