Flow Meter Calibration And Re-calibration Techniques

1. FLOW METER CALIBRATION & RECALIBRATION Flow meter can be calibrated using any of these following methods, 1, Wet calibration method using the fluid flow. 2, Flow rate measurement of physical dimensions. 3, Electronic or mechanical dry calibration methods. It is common to make measurements employing a series of several instruments acting together. By using separately calibrating the segments of a system, gives adequate accuracy rations for each calibration and calculate the overall system accuracy by the previously described method. Wet Calibration In a wet flow meter calibration method, using actual fluid flow, normally provides the finest calibration accuracy for a flow meter and sees use where accuracy could also be a major concern or when the structure of the meter doesn't permits itself to any other methods. Precision flow meters usually see wet calibration at the time of manufacture. After maintenance, one must often replace and re-calibrates them. The right time interval between these calibrations varies relying on the user’s experience with the meter and thus the importance of the measurement. When performing the calibration according to the initial specification of the manufacturer, only if the adequate facilities are available. Otherwise specify the minimum value you'd wish to calibrate, the quantity of points you are taking, and thus the fluid viscosity. www.dimemarine.com 1

2. Wet calibrations test performs along with water, air, or hydrocarbon fuels using any of these standards: weight tanks, volumetric tanks, pipe provers, or master flow meters. Physical Dimensions Standards In static calibration method, the flow starts quickly to start out the test and holds constant during the test, then stops at last. Compare the total reading from the flow meter with the load or volume you collect and calculate the meter performance. A static system operates best with flow meters that have minimum sensitivity to low flow rates. It doesn't shows optimum results with high-end digital meter readings, and the errors obtained with a short periods of low flow at the starting and at end of the test. Because of this the static systems aren't widely used. A Gravimetric calibration can also be utilized during a dynamic mode. By this method, the flow is about at a mild rate before the start of the test. The initial measurements reading performs together to start out the test and again, after the required collection period, to end the test. Completely dynamic systems are limited by speed or response consideration and thus the overall difficulties used. Hybrid Dynamic Start & Stop The key to the dynamic start-and-stop reading system is that the planning of the floodwater valve that switches the flow in and out of the standard. During a well-designed system, the actual diversion time is way smaller than the gathering time, and thus the flow pattern through the diverted is independent of flow. In this context, the limiting factor system uncertainty is that the desired accuracy of the load or volume standards. With care, you'll reduce errors to low values of 0.1% reading under laboratory conditions. Master Flow Meters Perhaps the foremost common method of wet calibration is comparing the output of the meter under test with one or more flow meters that are certified against high-accuracy standards, mentioned as master flow meters. You’ll construct a touch master meter comparison test stand at less cost than other wet calibration methods. If properly designed and maintained, it's capable of calibrating flow meters to a tolerance of ±1% reading or less. If you're selecting flow meters as masters, consider the required range of the test stand, the required accuracy, the properties of the test fluid, and thus the allowable head loss. www.dimemarine.com 2