Water treatment plants, chemical processing facilities, and offshore platforms all seek to maximize efficiency, and in metering pumping processes leveraging the turndown capabilities vastly decreases the waste of chemicals.
Turndown is expressed as a ratio of the metering pump output. If a pump is capable of a maximum of 1,000 gallons per hour (gph) and it has a 100-to-1 turndown ratio, then it can be adjusted to a flow rate as low as 10 gph and still perform within its accuracy rating.
But a turndown ratio means little without an accuracy rating as well. For example, the example pump above with an accuracy rating of 1% max flow rate means that at a flow rate of 1 gph, the pump may be pumping +/- 10 gph, possibly 1,000% the intended amount of fluid.
The entire purpose of a metering pump is to dispense a specified amount of fluid. Turndown is so important in that varying levels of chemicals or raw materials might be required in the moment. Being able to modulate the amount of processing chemicals will reduce the overuse during processing.
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