| 摘要 |
An electrical insulator in accordance with the present invention includes a body, a ventilation passage, a bore, and a duckbill-shaped valve. The ventilation passage which extends between a first opening and a second opening in the body. The bore also extends through the body and is spaced from the ventilation passage. The duckbill-shaped valve comprises at least two walls. The walls are connected on opposing sides of the second opening and at an angle with respect to the body and each other so that the walls engage each other and define a space above the second opening and below the walls. A slit is formed between the walls. The portion of the walls at the slit normally remain in contact with each other until a cracking pressure is reached.
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