AWWA ACE68618

This powerpoint presentation presents an AwwaRF project on issues with ultraviolet sensors that included: guidelines and standards do not agree; commercial sensors do not meet guidelines; lack of consensus on key sensor properties should be defined and measured; and, poor sensor performance observed in prior studies. Project approach was designed to develop UV sensor guidelines and included: a literature review and vendor survey; European and North American field evaluation; measure properties of commercial sensors in laboratory; analyze impacts of measured properties on dose monitoring using intensity and CFD-based models; and, obtain stakeholder feedback on recommendations. Guidance was developed with input from UV vendors that included the following: vendors maintain 3 primary reference sensors to calibrate working reference sensors; properties of primary reference sensors measured; total uncertainty of 5% or better; calibrate LP sensors using LP light and MP sensors using MP light; UV sensors have germicidal spectral response; and, reference sensors should have an independent readout. Guidance included: field calibrate duty sensors using reference sensors; use three reference sensors to minimize reference sensor uncertainty; wet sensors are not practical for reference sensor checks without special provision to easily swap duty with reference sensor; control rotational orientation of UV sensors in sensor ports; specify lower bound of working range; and, final report gives properties for reference and duty sensors defined to meet 20% reference sensor check criterion specified by UVDGM. Includes tables, figures.