Near Intersection of I-35 & I-90 Southern Mn. | I worked with KRK and we saw flow meter damage such as his pictures show. This was due to running the tanks empty or low.
In his picture above, the shaft below the turbine orginally was part of the turbine assembly. The turbine is supported by two ceramic bushings in the housing. The ceramic is tougher than the steel shaft in the turbine. When vapor is present rather than pure liquid, the turbine spins at extreme speeds causing wear on the turbine shaft. The vapor tends to form in pockets and passes through the flow meter in bursts causing the excessive speed.
The one in picture got so bad that it wore the shaft completely off. You can also see wear due to the other ceramic bushing. Even before breakage the turbine can wobble due to the slop in the shaft and the bushings allowing the outside of the turbine to literally rub on the housing causing it to turn slower than it should. As stated earlier, the system then tries to compensate by opening the control valve more to get the turbine to the correct speed for the target rate, width and ground speed. This can result in over application.
When the tanks are run very low or empty, vapor rather than liquid passes through the flow meter which causes the turbine to spin at tremendous speeds. On a 440 this may be shown as large spikes in the applied rate. During this time, the turbine experiences accelerated wear as there is really no lubrication involved.
Running the tanks empty or very low will eventually result in the above failure and causes incorrect application during that last portion of the tank since the flow is partially liquid and partially vapor.
Edited by tedbear 2/26/2017 08:49
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Ag Leader Direct Command, raven accuflow. unexplained overapplication.
