Near Intersection of I-35 & I-90 Southern Mn. | If the Raven meter cal for 10 gallons of water is 700, then the Raven meter cal for 10 pounds of Actual "N" would be 700/4.14 = 169. So for 1 pound of Actual "N" the meter cal becomes 169/10 = 16.9 which rounds to 17.
The conversion factor of 4.14 come from the fact that a gallon of Liquid NH3 would contain 4.14 pounds of Actual "N". This varies with the temperature and pressure but is the "best" guess for a conversion factor.
Since most farmers like to think and talk in terms of Pounds of Actual "N", the above conversion gets involved. With an Ag Leader system, if the operator indicates that NH3 is involved the system handles the conversion factors internally and the operator should enter 70 for the meter cal. If one uses the "Raven NH3 cal" number, the conversion gets applied twice and the end result is that you tank covers lots of acres since you are only applying about 1/4 of what you intended. Ask me how I know.
Fortunately I caught this with the first tank of NH3 that I applied. When applying my first tank with the Ag Leader system, indications on the screen seemed fine but I noticed the pressure gauge on the manifold was reading much lower than I expected from the past. I had done about 15 acres so I expected that the tank should be about half empty. I stopped and checked the float gauge on the tank and found that the tank was still quite full. It was then that I investigated and found my error.
I changed the meter cal and my indicated pressure increased. I set my target rate for 3/4 of the desired rate and reapplied the 15 acres that I had previously applied with the incorrect meter cal. From then on, I remembered how the meter cal needs to be entered for NH3 with an Ag Leader system.
Edited by tedbear 2/20/2024 07:45
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JD RC2000 NH3 Flowmeter Setup
