Water meters are not all created equal, study finds


Steven Barfuss,
Utah Water
Denver, CO, U.S.A. — (METERING.COM) — September 23, 2011 – Not all water meter types are created equal and some manufacturers produce a superior product, a new study from the U.S. Water Research Foundation has found.

Some meter types pass the American Water Works Association (AWWA) registry standard tests more consistently than other meter types, the study found. And surprisingly it says, most manufacturers that publicize AWWA standard compliancy do not consistently meet the organization’s metering standards.

The study, “Accuracy of In-Service Water Meters at Low and High Flow Rates”, was led by Steven Barfuss of the Utah Water Research Laboratory. Its aim was to examine the accuracy of in-service water meters at a range of flow rates, and specifically to gain a more detailed knowledge of low flow accuracy and the effects on the accuracy of age, throughput and particulates.

A total of 450 new meters and 595 pulled meters from water utilities across the United States were tested. These meters were of various sizes, from 5/8-inch to 2-inch diameter.

The results found that some meter types were capable of accurately measuring flow at flow rates well below and well above the AWWA standard rates and that other meter types were not capable of measuring these flows. In particular the fluidic oscillator type meter consistently met the AWWA maximum accuracy standard at new condition and after full life of throughput. The new nutating disc and piston type meters most consistently indicated registry accuracies above 95 percent at the minimum AWWA flow rate.

Degradation trends for individual meter types were most apparent at low flow rates after testing over full life cycles. The nutating disc type meters maintained the most consistent low flow accuracy, while the multi-jet and single jet meters had the largest reduction in registry accuracies from new to full life.

From the testing of the pulled meters, it was found that potable water quality had less of an effect on meter accuracy than did sand and other particulates. Generally, most of the degradation trends for the pulled meters correlated closely to the new meter laboratory degradation trends.

The researchers state that the results should provide a basis for water utility managers to make decisions regarding meter accuracy, use and replacement. Meter type should be an important component of the decision process for meter selection.

According to the study, citing a 2006 interview with Master Meter’s Ron Koch, the majority of residential and commercial flow meters in the U.S. are from six manufacturers, Sensus, Neptune, Hersey, Badger, Master Meter and Amco. Approximately 85 percent are of the positive displacement design and 15 percent of the multi-jet design.