| 摘要 |
A combination pressure/vacuum relief valve is formed by a closed end cylindrical body having a first port providing communication with a fluid containing vessel and a second port providing communication with the atmosphere. A piston valve within the cylinder is normally seated on a valve seat between the ports with the respective end portions of the piston rod projecting through the closed ends of the cylinder. Each end of the cylinder is provided with a cage supporting a pressure responsive fuse rod interposed between the outwardly projecting end of the piston rod and the opposite end of the cage. When the fluid pressure within the vessel falls below or exceeds a predetermined value, such pressure axially moves the piston valve in a respective unseating direction for providing communication between the interior of the fluid vessel with the atmosphere.
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