open channel without restrictions, partially full pipe
The AVFM 5.0 system simultaneously measures the level and the velocity of the fluid in order to calculate the flow rate into an open channel or a pipe.
The STINGRAY portable instrument works for a very long period of time powered by alkaline batteries and stores measurements of water level, velocity and temperature in open channels and in partially filled or pressurised pipes without the need for constrictions or weirs.
The immersible ultrasonic sensor continuously monitors both the velocity and the level of the channel or piping by transmitting high frequency sounds into the liquid, through the pipe wall. The pulses are reflected and sent back to the fluid. Because of the fluid‘s movement, the reflected sounds return to the sensor with an altered frequency (Doppler effect). The best accuracy is achieved if the flow does not have an excessive turbulence and the velocity on the sensor is not less than 1 m/sec. The channel, right upstream of the sensor, must not have abrupt changes in the level of the bottom and a slope of no more than 3%. The conditions downstream of the sensor do not affect the measurement if the surface profile is not changed right above the sensor itself.
To calibrate AVFM 5.0 just insert the pipe diameter or the channel width and choose the measurement unit from the menu. The flow rate, level and velocity can be expressed in gallons, litres, ft³ or m³. The calibration parameters remain stored even in the absence of tension. For STINGRAY no calibration is required. On the front there is a bar indicating the velocity, level, temperature, battery status and finally the used/available memory. The display automatically turns off after 60 seconds to save power. The software allows the user to set the sampling intervals, to download the files and to get an indication of the variables. The logger displays the files and the calculated velocity in trend graphs and tables, including the minimum and maximum values, the average and total flow rate in normal measurement units.