Near Intersection of I-35 & I-90 Southern Mn. | Pine Trees - 11/9/2010 20:46
Everything ran real well this afternoon until I weighed a tank back. Insight said 6050 lbs and scale in town said 4080 lbs. I am using the cal number on the flowmeter which is 73.0. The flowmeter and servovalve are Hiniker new style. It appears I applied at 67.4% of the intended rate. So 6050x73=441650
And 441650/4080=108.47
Do I use 108 as my new pulses per gallon?
I am probably not explaining everything real well so please ask question.
As I stated below the expected cal number would be 73.0 for this Hiniker system. Again be careful that you are not confused about measuring your situaton in pounds of NH3 vs pounds of N.
If the Insight said 6050 pounds of NH3 and the Scale said 4080 pounds of NH3, the flowmeter is reading too high. My guess is that the cooler is not properly keeping the NH3 in a liquid state. When this happens some of the product is liquid and some is gas. The gas will spin the turbine faster than it should resulting in a higher reading than is actually the case. The control circuit will assume that this value is correct and close down the control valve in an attempt to get apply the correct rate. This will result in under application.
Using your "new" value of 108 might give you a good reading for the next tank but this would only be true if the proportion of gas to liquid would remain the same. If vapor is the problem, the solution is investigate the reason and correct it.
I would have the Insight show the rate of "N", the rate of "NH3" and also the flow rate. The flow rate will be an indication of the RPM of the turbine in the flowmeter. If this value is unstable and jumping around a lot, this is an indication of pockets of vapor passing through the flowmeter. If the value is unstable, slowing down may allow the value to stablize. This problem is fairly common when systems are not plumbed properly or due to a restriction in the product flow. Larger bars, higher rates, and higher ground speeds require a larger flow rate which increases the chances of this happening. Colder weather reduces the tank pressure and is a very common cause of this type of problem. |
Insight and NH3
