| 摘要 |
PURPOSE:To prevent the unprepared opening of a low pressure limit valve which is closed when the fluid pressure in a passage has dropped, by keeping the valve closed as long as no resetting operation is effected when the pressure of the passage has risen again. CONSTITUTION:When a valve element 12 is maintained in its open position, a first chamber 4 and a second chamber 5 communicate with each other and a fluid supplied to an inlet port 2 flows out of an outlet port 3. When the pressure of the fluid in the first chamber 4 has become lower than a level set by an adjusting screw 17, a second diaphragm 14 is pushed into the second chamber 5 by a spring 18 because of the drop of the pressure acting to the pressure receiving side of the diaphragm, so that the valve element 12 is moved together with a valve spindle 7 and brought into pressure contact with a valve seat 13 and the chambers 4, 5 are disconnected from each other. Even if the fluid pressure in the first chamber 4 rises again beyond the set level, the valve 12 is not opened because the effective pressure reception area of a diaphragm 8 is previously set larger than the cross-sectional area of a passage 6. |
