About model calibration and criteria

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Model calibration is the process of iteratively adjusting model input parameters

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to achieve a reasonable match between model output and field data.

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Calibration increases accuracy of the model,

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instilling confidence that your model accurately predicts existing conditions within reasonable margins of error,

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which is vital for its use as a planning tool.

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A calibrated InfoWater Pro model is required for accurate fire flow, water quality, and energy analyses.

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This gives you an understanding of how water moves through your system,

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as well as confirms your connectivity, pump curve accuracy, controls, and hydrant calibration.

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There are two types of calibration: Extended-period simulation (EPS) calibration and steady-state calibration.

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In EPS calibration, you compare tank levels, pump run times, junction pressures,

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and known flows to your field data, generally over a 24- to 48-hour simulation.

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This type of calibration validates system connectivity, diurnal demand patterns, and system controls.

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In most EPS calibrations, your goal is to have hydraulic grade line elevations (HGLEs) within five to 10 feet of field values,

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and tank level fluctuations within three to six feet of field values.

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You also want to be able to explain any discrepancies found when comparing your model data with the field data.

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In steady state calibration, or hydrant flow calibration,

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you compare pressures at residual hydrants against those in the model when introducing hydrant flows as “point demands”.

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This means that field data from standard hydrant flow tests

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are used to verify whether the model’s pressure predictions are within the 5- to 10-ft HGLE range.

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By using multiple hydrants, you also have multiple points of data to compare.

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When performing hydrant flow tests for calibration,

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it is important that the flows to which you are calibrating are less than the required fire flow values.

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Otherwise, you may not be calibrating your model sufficiently to test all fire flow concerns your model needs to predict.

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Ideally, you want calibration flows that are as high as your fire flow requirements.

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This way, you can ensure that you are calibrating within the range of flows with which you are concerned.