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GENERAL PROCESS - REF. #GP007 | View PDF
THE CHALLENGE
Liquid flow meters are a critical part of nuclear reactor cooling systems. Water must be delivered to the reactor at all times and flow meters are used to monitor this. If a flow meter detects a decrease in flow, which happens when intake pipes clog with mud or debris, a backup pumping system is immediately activated. It is vital that these flow meters are accurately calibrated on a regular basis.
THE BROOKS SOLUTION
Brooks Oval gear meters are used by the metrology labs in nuclear plants to calibrate the flow meters out in the plant. These positive displacement meters have four times the accuracy of other meters and remain accurate for up to four years before needing recalibration.
Various types of liquid flow meters may be used at a nuclear plant. Rotameters are used in places where it is necessary to see the liquid inside a pipe, or for low pressure. Regardless of the type of flow meter, it is important that they are calibrated regularly because the liquid they measure is not always clean water.
Brooks Oval gear flow meters provide 0.5% to 1% rate accuracy of viscosities above 5 centipoise which is considerably greater than the 3% to 5% which is common with other meters.
In a typical lab calibration session, the meter being calibrated and the Brooks Oval gear meter are in the same water line. A tank is filled with distilled water so it contains no contaminants, and the water is pumped from the tank and through the meters. Water goes first through the Brooks Oval gear meter which sends a magnetic pulse to a computer. Custom software translates this information into a flow rate. Farther down the line is the meter under test. A start time is entered into the computer and for one minute the system counts the pulses from this meter. The flow rates of the two meters are compared to determine the percent of accuracy of the test meter. In some cases, the flow has been restricted because of a contaminant. The test meter is then cleaned and brought back to within a specified tolerance.
Using Brooks Oval gear meters in this type of calibration system will ensure that the nuclear reactor will have the water flow necessary to keep it from overheating.
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