Flow meters were utilized throughout the HMGA Water Project in order to determine water flows generated by processing carrots and other root vegetables. These values are used to properly size treatment equipment.
The flow meters used included the Hach FL900AV meter with Hach Flow-Tote 3 AV sensor. The two components communicate with one another via a cable to measure and record. The Hach flow meters were chosen due to their reliability, ease of use, and their ability to determine flow in a variety of conditions. Often the water being discharged from the facility would have high solids content which would likely cause improper readings if other types of sensors had been used (mechanical sensors would likely get clogged/jammed for example). This flow sensor has three electrodes pointing out of the sensor base which are designed in such a way as to prevent the build-up of debris on the sensor. Pipe bands are used to secure the Flo-Tote 3 sensor inside an outlet pipe; they ranged in size from 8” to 14”, but other sizes are available.
The software used to compile data, FSData Desktop Instrument Manager, allows the user to graph flow, velocity, and water level. An exporting function is also available to convert data to a .csv file which is compatible with Microsoft Excel. FSData is also used to calibrate the instrument at installation.
The flow sensors could not be placed in pipes with a diameter less than 8” due to the width of the sensor, water would flow beneath the flow sensor due to the curve of the pipe. It can operate between -18°C to 60°C. The accuracy of the Flo-Tote 3 sensor was ±2% of reading.
Installation and Use
An appropriate band is chosen based on the pipe diameter. The Flo-Tote 3 sensor is attached to the band using screws and the cable from the sensor is affixed to the back of the band using zip-ties with ends snipped in order to have minimal effect on the flow. The sensor and band are then placed into the outlet pipe as far in as possible to minimize turbulence and create a streamlined flow. Lastly the sensor is connected to the logger.
The logger is then connected to the computer using FSData Desktop Instrument Manager. The Set-Up Wizard found within FSData requires the pipe diameter and current water level measurements be manually measured and inserted into the program. This is required once at initial start-up.
Logging measurements can be set at variable time intervals to suit the application; for example, readings can be taken every 60 seconds. In such cases, there is a need for greater program memory to capture data over longer periods of times. The data is collected by connecting the Hach FL900AV meter to a laptop computer via a cable.
Taking flow measurements in regular intervals provides a clear description of a set period of flow. Peak flows will be displayed as well as regular flow conditions.
- Hach Company (2013). Flo-Tote 3 sensor: Open channel flow sensor – User manual. Retrieved from http://www.hachflow.com/pdf/Flo-Tote3Man.pdf on 22 June, 2016.