Metering liquid into a water pipeline - using two flowmeter-driven metering pumps in main and by-pass pipes

摘要

In an apparatus for metering liquids into a water pipe with a flowmeter driving a metering pump and a by-pass for the flowmeter controlled by a valve, a liquid storage vessel and a supply pipe, (a) a further smaller flowmeter driving a smaller metering pump is provided in a further by-pass for the main flow meter (b) the inlet to this further by-pass is situated upstream of a pressure-retaining valve and can be closed off by a control valve regulated by the water flow. Permits metering of the liquid to the water pipe to be maintained with pre-determined accuracy over a flow range of 1:500.