| 摘要 |
A device relieves a positive pressure difference between the inside of a vessel and the outside of the vessel through an opening in the vessel. The device has a base portion, a cap portion and a biasing means. The base portion has a means for mounting the device in the opening; a cap seat providing an orifice through which the pressure difference may be relieved; and a generally hollow body portion attached to the cap seat and extending concentrically with the cap seat into the vessel. The cap portion has a cap having an external surface with a diameter larger than the diameter of the cap seat to retain the cap external to the cap seat in sealing relationship; a rod mounted concentrically and normal to the internal surface at one end, the other end extending into the body portion and terminating in a piston with a shoulder, the piston being in concentric sliding engagement within the body portion. The biasing means has a compression spring acting between the interior of the body portion and the piston shoulder to urge the cap into sealing relationship with the cap seat; and a damping means with the piston effectively dividing the body portion into first and second chambers, a channel communicating one chamber to the other and a fluid in the chambers so movement of the piston in either direction requires a portion of the fluid to pass through the channel from one chamber to the other.
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