Near Intersection of I-35 & I-90 Southern Mn. | Actually we may have some "gaps" in the opposite sense. That is areas at the start of a pass with less than full rate.
Our previous Hagie STS-10 was controlled by an Ag Leader system with a Servo Controlled hydraulic valve for rate control. This year we have a somewhat newer Hagie STS-12 which uses a PWM hydraulic valve for rate control. I did some testing with water in the yard and it seemed to work properly.
My Great Nephew does all the spraying and with our excessive rains we really only had one day to spray corn and then one day to spray soybeans and even those days weren't ideal. The corn was sprayed at 15 GPA. The soybean mix was sprayed at 20 GPA due to using Liberty as part of the mix.
He complained that the rate at the start of a pass was low but the system did eventually respond and overapply for a bit and then settle down at the desired rate. This had happened on the corn also but not as seriously. He indicated that if he started out the new pass quite slowly that he situation improved. He kept going as more rain was predicted and were able to finish the soybeans.
Since it did rain again, I had a chance to do some testing with water in the yard yesterday. I tried to adjust the PWM standby setting in an effort to put a "low limit" of sorts into the system. While doing my testing with water and a self-test speed, I could observe the calculated applied rate , pressure to the boom valves and the actual PWM value on a diagnostic screen. I observed these values with all sections spraying. As I shut off a section, the indicted applied rate would increase slightly, the pressure would increase slightly but the system would respond very quickly and reduce the PWM output to achieve the target rate with the section OFF. In other words it worked properly.
I did have the opportunity to test one of my end cap modifications for cleaning out the boom. The style using a nozzle body adapter and a cap seems to work so I will probably proceed with that style. I may have some clearance issues at certain locations.
I then shut OFF another section with the same results. I continued shutting off the boom sections one by one. Each time the pressure would increase somewhat, the rate would be a bit high but the system would react to correct the PWM output and the applied rate was reduced to the target rate.
Finally I shut off the last section, the applied rate went to zero as expected BUT the pressure dropped to zero and the PWM value dropped to zero. I was thinking that some pressure would still remain and the PWM value would be determined by the PWM limit settings. We needed pressure for agitation with the sections OFF and more importantly to have pressure for the start of a new pass.
I then looked over my controller settings more carefully. I'm embarrassed to admit that my error was then obvious. I had the control valve setting for "what to do when all sections are off" set to CLOSE rather than HOLD. That was why the pump was not running when the sections were ALL turned OFF.
This was my first use of PWM with a sprayer. The other setups that I've used have been with a motorized control valve in the product line or a servo valve to control the pump. Maybe the PWM setup defaults to CLOSE. Whatever the reason switching to HOLD was warranted. Now the pump continues to run with all sections OFF thus maintaining boom pressure to provide immediate flow when sections are again turned ON.
Now by adjusting the PWM standby values, I can control the pressure to the boom valves when all sections are OFF. In other words maintain pressure to the boom valves while turning around to make a new pass. Upon starting to spray again, product will be immediately available and then the auto portion can fine tune the PWM output as necessary.
These values appear to be very dependent on the situation. My testing was done with Y-drops and 60' of width. A different standby value may be desirable for spraying other products at other rates for 90'. A cheat sheet for these settings may be useful for future reference.
Edited by tedbear 7/12/2024 07:52
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Ideas for cleaning out Hagie Wet Boom
