Near Intersection of I-35 & I-90 Southern Mn. | PigFarmer makes reference to setting a minimum flow. You may not be aware of this feature. Push and try to understand those other keys that you never push. They are there for a purpose. They may take away some of the "magic" that is often perceived.
If you push the Vol/Min key while spraying, the value shown is the number of gallons/minute that are passing through the system to the ground (assuming its is plumbed properly). This is really just the indication of the flow without any regard to ground speed or width. It can be very handy for troubleshooting. It is good to know what this value is when things are working correctly.
Unless your Raven is extremely old, you can set a "low limit" for the system based on Vol/min. To do this push and hold the Vol/min key until the display starts flashing. The flashing number is the current value for the low limit setting. By default this will be zero. However you can change this if you wish.
One situation where you might wish to set a low limit higher than zero is to keep tips from checking off or producing a poor pattern due to low pressure. For example, suppose in normal conditions everything is working fine but you need to slow down considerably to cross a waterway or avoid a utility pole. Because you slow down, the applied rate in automatic will be high for a bit until the system reduces the flow. This is fine and is desirable to maintain the proper rate but under certain circumstances, the flow will be reduced so much that tips check off or produce a poor pattern. By setting a low limit you can prevent this from happening.
This will result in temporarily overapplying until your speed returns to a more normal speed. Often this over application is more desirable than having a poor pattern or a tip shutting off.
Remember the low limit is in Gallons/minute and not Gallons/acre.
One method to set this value is: Use a tip chart and look up the tips you are using. Determine the flow per minute for one tip from the chart by looking for the pressure you wish to exceed. This will vary but might be 30 psi. See what one of your tips is putting out at 30 psi. Multiply that number by the total number of tips on your sprayer. This will give you the value to use for the low limit. Enter that value when the Vol/min is flashing.
Then when spraying at a normal speed, everything will work as before. If you slow down, the system will cut the flow back to maintain the proper Gallons/acre. If you continue to slow down, a speed will be reached where the low limit you have set is reached. The system will not reduce the flow past that point. An alarm will sound and a message is shown to make you aware that this is happening. You will be overapplying. When the obstacle is passed and you return to a more normal speed, the alarm becomes silent and operation returns to normal.
If you set the low limit too low for your tips you don't gain the benefits of the low limit setting. If you set the low limit too high for your tips, you will be overapplying in more normal situations.
Rather than use a tip chart, a quick and dirty method to set the low limit is to watch the Vol/min and gradually slow down. Purposely continue to slow down until you notice problems with your pattern or the tips check off. Note the Vol/min at that point. Set the low limit slightly above that value.
I don't believe that having the low llmit inadvertently set too high is your problem since if this is happening, you would notice the warning message.
Edited by tedbear 7/4/2024 09:23
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Raven 460 manual rate control
