| 摘要 |
<p>Pressure balancing foam valve (50) includes a body (52) having an inlet (54) at one end and an outlet (58) at an opposite end, and having an annular passage (62) therethrough. A first stage pressure regulating assembly (86) is disposed within the annular passage of the valve and includes a shaft (90) and a one-piece pressure disc (88) which is urged into a seated position against end portion (70) and the inlet (54) by spring (112) interposed between pressure disc (88) and a second end (11) of the shaft. The spring (112) holds pressure disc (88) during low pressure conditions to prevent flow and opens with increasing pressure to permit flow through the valve. A second stage pressure regulator is a venturi-shaped annular passage (138) through a wall portion of the outlet (58). A high pressure inlet (54) and foam outlet ports (154) are connected to a foam delivery system. The pressure disc (88) and venturi (138) together provide a differential pressure within the valve proportional to changing flow rate and pressure.</p> |
