Near Intersection of I-35 & I-90 Southern Mn. | Changing the valve Cal (the 2123 number) may offer better performance. The reaction time to a change in speed is related to many factors besides the cal number. The plumbing style and arrangement play a huge part in the overall picture. The size of the spray tips, target rate and ground speed are also important to the reaction time.
Not knowing your target rate or tips, it is difficult to determine to know if they are reasonable. The applied rate varies as the square of the pressure. So to apply twice the product with a given tip requires four times the pressure. A 1 1/2" control valve is available which is another thought as it will change the product flow more quickly with everything else remaining the same. The downside of having "too large" a control valve is poor control at low rates or speeds.
The Valve Cal for a standard control valve such as your 1" valve (the 2123 suggested number) is not a single number. It consists of four individual digits each of which affects the behavior of the control valve.
Lets call the val cal ABCD.
The digit in the A position is the valve backlash digit. This accounts for the amount of backlash or slop in the gears in the control valve. This digit is only involved when the butterfly needs to change direction. Suppose the valve has been opening up, then the gears would be "tight" and any change in the increase direction would be immediate. If the valve needs to close then the slop in the gears wouldn't change the butterfly immediately. The backlash digit gives an extra "shot" of electricity when the direction is changed to overcome the backlash.
The digit in the B position is the speed digit. This is the relative value of the speed of moving the valve when the applied rate is considerably off target. For a standard valve changing this from the suggested "1" to a larger number should cause the valve to respond quicker.
The speed of the valve when the applied rate is close to the target rate is fixed and cannot be changed. This is so that the valve will not overshoot or undershoot the target rate as the applied rate gets close to the target rate.
The digit in the C position determines when the system should be making major movements in the control valve or minor movements. Major movements use the B value, minor movements use the fixed value. Increasing this number will cause the major movements to be used more quickly in the process.
The digit in the D position determine the Percentage tolerance that you are shooting for. Although it might seem desirable to have this as small as possible (1), this is unrealistic and the usual value for spray is (3).
So for your system you might change the valve cal from 2123 to 2223 or 2323 (changing only the second digit). This may or may not help out your situation.
Another possibility is to set in a low limit. This feature allows you to set a minimum gallons/per minute (note minute not acre). That means when you slow way down for a waterway or corner the system will only decrease so far. This does result in some over application but it may help maintain a good pattern and the system can then "open up" from that point as you return to a normal speed.
Again the plumbing, tip size, rate, speed etc are all involved. Changing the electronics cannot makeup for restrictions in these areas.
Edited by tedbear 5/10/2013 06:55
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Raven liquid control valve speed
