| 摘要 |
<p>A fluid flow control system includes a valve 12, in which a control element 23 regulates flow through a metering orifice 21, 24. A further control element 27 regulates flow through an orifice 22 downstream of the orifice 21, 24 and is responsive to the pressure downstream of the orifice 21, 24 and to an opposing control pressure on a line 28. The element 23 is positioned in accordance with the pressure in a chamber 36 controlled by an electrical valve 32, 33, 34. The pressure in line 28 is set to provide a required pressure drop across the orifice 21, 24.</p> |
