| 摘要 |
PURPOSE:To maintain automatically piping negative pressure constant when the balance between the piping negative pressure and a set negative pressure is lost, so that flow can be accurately and rapidly measured, by connecting both side negative pressure chambers separated by a diaphragm of an atmosphere introducing valve to a constant pressure valve between a discharge port and a flow meter at the negative pressure source side. CONSTITUTION:When negative pressure of a negative pressure source 13 set by a constant pressure valve 22 is applied to a negative pressure chamber 16c, while being applied from the negative pressure source 13 to a piping 11, the negative pressure is introduced into a negative pressure chamber 16e through a flow meter 12. And when the introduced negative pressure exceeds a set negative pressure, a valve body 17 moves to the negative pressure chamber 16e side and opens an atmosphere introducing hole 16a so that the atmosphere corresponding to the opening of said hole is introduced into the piping 11 to reduce the negative pressure in the piping 11. When the negative pressure in the piping 11 is reduced too much, the valve body 17 is moved to the negative pressure chamber 16c side to reduce the opening of said hole 16a and the introduction of the atmosphere from said hole 16a so that the negative pressure in the piping 11 is increased. The negative pressure in the piping 11 is maintained constant by the repetition of this operation so that the flow property of a negative pressure controlling valve can be measured under a certain negative pressure condition. |
