| 摘要 |
Disclosed is a safety valve installed in a tank of a vessel carrying oil or chemical substance to discharge supersaturated gas produced in the tank and to adjust an internal pressure to a normal level when a negative pressure is produced in the tank. The valve comprises a lower body; an upper body mounted onto the lower body; a valve stem extended from the upper body to the lower body; and a disc provided on the valve stem and positioned between the upper and lower body to shut out a communication between the upper and lower body. The disc has a groove on an underside thereof, with a protruded portion being formed along an edge of the disc, a Teflon bushing is interposed between the disc and the valve stem, and the disc has a large diameter than an internal diameter of the lower body. The upper body has a straighten portion on an internal lower edge thereof, the straighten portion is formed in such a manner that until the disc is raised to a maximum stroke the straighten portion is parallel with the disc, and a space is formed between a side of the disc and the straighten portion of the upper body.
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