Typical in-situ flow meter calibration

The most common type of dye dilution work we encounter is the in-situ calibration of flow meters. Largely due to the fact that many flow meters have been installed with little thought of future performance or calibration. Dye dilution lends itself as a calibration technique that is suitable for the in-situ calibration of many difficult flow measurement applications. The basic equation to determine flow rate using dye dilution is:

Q=q * C/c

Where:

• Q = the flow of the fluid being tested.

• q = the injection rate of the dye mixture.

• C = the concentration of the dye being injected.

• c = the sampled concentration of dye.

The following chart is an example of an in-situ calibration of a flow meter at a waste water treatment plant. The flow meter was a new installation of a point velocity type area velocity flow meter. The physical characteristics of the location would not allow a standard velocity profile to be completed and dictated the installation of the velocity sensor be considerably offset from the centerline of the flow channel.

By reviewing the data, the flow should good precision and appeared to be working well. However due to the incompatible site conditions, the data shows considerable bias error as would be expected. Calibrated the flow meter in-situ allowed for a k factor to be entered into the flow meter and correct for the error. This allowed the owner to choose an economical metering system while avoiding the expense of more complicated flow meter technologies and associated installation costs.

Services We Offer

Our staff have over fifteen years of dye dilution, flow meter installation, calibration and maintenance experience. We offer expert technical assistance in:

• In-situ flow meter calibration/verification by dye dilution or other techniques.

• Training programs and consulting on dye dilution and flow monitoring techniques.

• Flow meter audits - meter type, age, location, suitability for calibration, data management.

• Calibration of secondary instrumentation.

• Development of a meter calibration and replacement strategy.