Field Evaluation of Low-cost Ultrasonic Flow Meters
Can relatively low-cost Doppler flowmeters be used in field applications for continuous gate operations?
Need and Benefit
Irrigation project managers are constantly seeking low-cost methods for accurately measuring irrigation deliveries. Acoustic Doppler flowmeters are often an attractive option because they cause no head loss, are easily installed, provide supervisory control and data acquisition (SCADA)-compatible outputs, and can be applied to a wide variety of flow situations. Acoustic Doppler flowmeters are available for prices ranging from about $2,000 to $18,000, depending on the degree of sophistication.
The Bureau of Reclamation's (Reclamation) hydraulics laboratory in Denver has fielded numerous questions in the last few years from area office personnel and irrigation districts regarding the accuracy and suitability of these meters. Now that laboratory tests have been provided, questions inquiring about the use of these meters in automation have been regular.
This project would undertake a field demonstration in which a low-cost Doppler meter would be evaluated against other accepted flow measurement methods to determine field accuracy, establish limitations on application, and develop firsthand experience with the meters use for automating a gated turnout. This study would be a followup to a study performed a few years ago in which meters were evaluated in the laboratory environment.
By conducting a nonbiased field evaluation of a low cost meter, Reclamation engineers can help irrigation districts and area office personnel best identify how there meters can be used to automate irrigation turnouts.
Some may argue that these meters are commercially available and, thus, require no evaluations to determine their accuracies. Unfortunately, this theory is flawed because many manufacturers market their products to sell and not necessarily to provide accurate and reliable results. A nonbiased comparison would remove any sale-increasing slants that may be added to product descriptions. In addition, many manufacturers don't follow their products after installations are complete. This study would allow the meter use to be documented over time to see how accurate meters are in field situations.