| 摘要 |
Control valve is for use in an upstream filter for a water filtering device comprising (i) a vessel contg. a filter bed of particulate material, (ii) one or more distributors, (iii) an inlet pipe for contaminated water and (v) a covered outer pipe for purified water in the upper section of the filter. A valve housing is provided with a membrane dividing the housing into a streaming chamber, and a pressure chamber. A liq. stand pipe has an upper surface that forms a cover lying approximately level with or above the level of the outlet pipe, and is provided with a tap at its base. A bubble pipe is lowered into the liq. stand pipe and connected to a compressed air source for supplying a constant amt. of air. A cable connects the pressure chamber with the upper ends of the bubble pipe. An inlet pipe faces the membrane to form a valve position which cooperates with the membrane, so that the pressure in the bubble pipe and hence that in the pressure chamber, urges the membranes against the inlet pipe valve position, thereby regulating the inflow through the pipe and ensuring that both the liq. surface area in the filter and the outflow of purified water through the fixed outlet pipe both remain constant. |
