| 摘要 |
A pressure vacuum vent has a body with means to vent an underground tank having vapors therein when the pressure within the tank exceeds a predetermined pressure and to allow ambient air pressure to enter the tank when the tank has a vacuum exceeding a predetermined vacuum. The body has a housing, which is open at its upper end, mounted thereon and extending upwardly therefrom with a cap mounted on top of the housing and spaced from the top of the housing to form passage means therebetween to allow vapor from the tank to flow upwardly therethrough. A cylindrical shaped shroud, which is preferably a single continuous member, is disposed in surrounding relation to the cap and the upper end of the housing to prevent any driven moisture from entering the passage means formed between the housing and the cap while still allowing vapor to flow only upwardly from the passage means through the shroud.
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