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GENERAL PROCESS - REF. #GP003 | View PDF
THE CHALLENGE
For proper operation, power plant control valves must close leak-tight. The leak integrity of a new or rebuilt control valve is tested and recorded before placing it in service at a critical location. If the control valve is found to be faulty, it is either returned to the vendor or sent back to the repair shop. The valve leak rate must be measured accurately to help the repair shop determine what was wrong with the valve and what to do about it. The flow measurement must also carry an NIST traceable calibration to satisfy documentation requirements.
 THE BROOKS SOLUTION
Mass flow meters are a useful tool for leak testing. They are simple to use, accurate, and provide a recordable output. The Brooks Model 5860E can accurately measure very low leaks. The high operating pressure rating and low pressure coefficient also allow leak testing at high pressures. Since mass flow meters have no moving parts they can be safely over range, which often happens during leak testing.
A simple test fixture is made by installing a Brooks 5860E mass flow meter upstream of the valve to be tested. The mass flow meter is powered by a Model 0151 power supply/readout. The Brooks Model 8601 precision supply pressure regulator provides a stable test pressure over a very wide flow range.
The flow meters are calibrated using a 70°F calibration reference temperature, which is normal for industrial applications. As an added convenience, the 0151 can be calibrated to read directly in engineering units. This is not a requirement, but makes developing the test procedure easier and reduces technician errors. |
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