Near Intersection of I-35 & I-90 Southern Mn. | AJN is correct, I know this from experience from using DC with NH3 for a couple of years. Use the number on the Raven flowmeter divided by 10 as the meter cal number for the DC with NH3. For example if your Raven flowmeter tag shows 710 as the meter cal for pulses per gallon, enter 71 in the Insight.
The direct command system is sophisticated enough to apply a conversion value for converting pulses per gallon to pounds NH3 and also "N".
By using 16.8 the system performs a conversion a second time and you are actually trying to apply only about 1/4 the amount that you really intended. This Fast Valve will have problems at low rates (you really don't want that low of a rate anyway).
I made exactly this same mistake with my very first tank of NH3 when DC was brand new.
After you have entered the correct value of Pulses for 1 Gallon of NH3, set the Threshold, responses and deadband according to the suggested values for a Fast Close valve. I think 2% is unrealistic for NH3 and would suggest a wider tolerance of 4-5%. Check the box to indicate that the valve is to close on the ends. The 743 indicated on your Fast Valve is the Valve Cal for a Raven system which is replaced by the the Response 1, 2, threshold etc. with an Insight.
When you go to the RUN screen, you will pick the field, the configuration and then the product which will be NH3. The next screen confuses some of our customers.
It defaults to using NH3 in pounds. This screen can be changed to using "N" in pounds. The setup can work fine either way if you understand what it means.
If you pick NH3, then your target rate should be entered in pounds NH3 desired per acre. The actual amount of "N" applied per acre will be 82% of that value (NH3 is 82-0-0).
If you pick N then your target rate should be entered in pounds N desired per acre. The actual amount of "N" applied will be this value.
Since most farmers refer to the amount of actual "N" they desire, the second method may be desired.
Let's try that with some numerical examples. If you pick NH3 and enter a target rate of 200 pounds of NH3 per acre, you will be applying 164 pounds of N.
On the other hand if you pick N and enter a target rate of 164 pounds of N per acre, you will be appying 164 pound of N.
Remember when you are using scale tickets to compare your actual application totals with the scale that the 82% factor may be involved.
Personally, I use the default setup of pounds NH3 per acre. Then the scale tickets should match up closely etc. I merely convert the pounds of N desired to pounds of NH3 for a particular field. I just divide the number of pounds of N that I think I want by .82 and then enter that number as my target rate.
If you pick RATE as one of screen display items, you have the choice of watching NH3/acre or N/acre. Actually you can have one item for Rate of NH3 and another for Rate of N.
The onscreen map will be based on the amount of NH3 being applied.
If you use a VR Rx Prescription, it will be necessary to pick the rate based on the units used in the Rx. If the Prescription file is in pounds of NH3, be sure to use that choice. If on the other hand the Prescription is in pounds of N per acre then pick that choice.
Edited by tedbear 4/11/2008 07:24
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Slow valves with DirectCommand and NH3
