| 摘要 |
Apparatus for blending at least two liquids, such as two different grades of petrol to provide a blended grade, has pumps (13 and 23) arranged to draw liquid from two separate tanks (11 and 12). The supply lines (16 and 17) from the pumps (13 and 23) each has a pair of solenoid-operated shut-off valves (17, 18 and 27, 28) arranged in parallel and separately controllable by a control unit (35). The flow in each supply line is monitored by a respective metering device (19, 29). The pumped liquids may be separately dispensed from nozzles (21 and 31), or blended liquid may be dispensed from nozzle (36). Valves (20, 30 and 40) control the dispensing of the liquids. When blended liquid is to be dispensed, the flow in the supply lines (16 and 26) is monitored and compared and if an error is detected in the desired blending proportion, then one of the shut-off valves (17, 18, 27, 28) is closed to bring the proportion back into the required range. The total volume flow of both liquids in any one dispensing operation may be accumulated and compared, the valves further being controlled dependent on that comparison.
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