| 摘要 |
<p>A three-way valve 10 suitable for caustic fluids comprises a valve body 14, a flow channel 30 with a valve seat 38, 40 at either end, a first 20, a second 22 and a common port (12, figure 1) which all communicate with channel 30 and a valve stem 16 with two valve members 52, 54 that extend axially beyond their respective seat 38, 40. Stem 16 is preferably formed as a single hourglass shaped piece and removably press-fitted into channel 30 wherein either bulbous member 52 or channel 30 deforms. Valve 10 may be plastic and may be pneumatically operated by a pressurized housing 72 acting on a diaphragm 76 that is connected to stem 16 by a control rod 48 with spring 86 biasing diaphragm 76 against housing 72. Stem 16 may be aligned by guide portion 44 formed by member 54 and valve body 14.</p> |
