| 摘要 |
<p>A pressure/vacuum vent of the present invention is mountable to the vent pipe of a storage tank. The vent includes a valve housing having a wall defining a chamber which is in fluid communication with said storage tank. It includes a first valve responsive to an over-pressure condition of a first pressure, a second valve responsive to an over-pressure condition at a second pressure; and a third valve responsive to an under-pressure condition. The first and second pressures are different so that one valve will open at a small pressure and the other will open at a larger pressure. The first valve is a poppet valve, and the second and third valves are diaphragm valves. The valve housing is contained in a vent housing. The vent housing includes a floor through with a bottom stem of the valve housing extends and which has drain holes. A cover is mounted to a top portion of the valve housing to cover the vent housing. The cover is spaced from a top of the vent housing.</p> |
