Hello. Board rc11, how to connect the pressure relief valve when all sections are closed. Thanks
How should that work? Does the relief valve need to be controlled? It could be connected to a relay that is set to activate when the sections are switched off.
When all sections close, the drain valve must be turned on to prevent the pressure in the system from being too high. When even one section is turned on, the valve closes again.
Plenty of systems just use a manual/spring loaded pressure relief valve. Might be easy to fit one rather than wire your motorized equivalent
But the distributor has a main on/off valve and when all sections close, the main valve is supposed to open.
This is typically called a “bypass valve.”
Setups with constant displacement pumps and simple on/off (no calibrated reflow) section valves usually have a bypass valve. You can think of it as a poorly calibrated reflow for all sections combined. It prevents a pressure spike when all sections turn off, and reduces the amount of control valve actuation required (faster response when sections turn back on). There would still be a manual/spring loaded pressure relief valve somewhere.
Setups with vane pumps with no agitation and section ball valves can also use a bypass valve. For those setups the product in the pump can eventually overheat without a bypass valve. I won’t argue that it makes any sense because a simple agitation line can remove that risk too.
The function should be “bypass valve on and flow meter ignored when all sections are off, bypass valve off if any sections are on”
I have a similar set up on my sprayer. I set it up to operate independently of the rate/ section control. Each wire that actuates a section valve I connected a wire to it with a diode in line. All the wires with diodes connect to a relay. That way if any one of the sections is on it sends power to the relay to open the circuit to the relief valve. When all the sections are deenergized it again closes the circuit to send power to the relief valve to open it. You need the diodes in place to prevent one section from back feeding power to the rest through the common connection at the relay.
Tthe idea is really good, thank you
Another question: when the main valve is turned off via diodes, what tells the flowmeter that the flow should not be measured?
I don’t know much about the rate control app yet, today was my first day playing with it and an RC15.
If you go to RC Settings → Machine → Relays then you can set a relay as type “Master”
The functionality of master is “relay is on when any section relay is on and off when all section relays are off” That’s what you want, but opposite. We can work with that.
Set a relay as type Master, wire the relay output to another external relay’s coil, a SPDT relay. Use that to invert the signal to the valve.
Perhaps David will add an “Invert Master” relay type some day so that the wiring doesn’t have to be special?
The sprayer I have used AgopenGps for autosteer and section control. I have a Raven 460 rate controller. The Raven does not count flow against the tank total if no sections are on. Previous to that I had a Micro Trak rate controller. That one did count flow towards the total with the boom sections off. On that one I added a relay in parallel to the relief valve relay. That relay opened the signal wire to the flow meter when all the sections were off so it would not add to the total.
Sk21 might be able to tell you how the RC11 works if it counts flow with sections off or not
Should be possible. I’ll have a look.
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I think it depends on the sprayer plumbing. On my own sprayer when the sections are shut off there is no flow through the flow meter, so no counting against the tank total. The bypass is before the flow meter.
Some sprayers are set up so that there is always flow through the flow meter. When the section valve closes to the boom it opens to the tank. In this case the product mode can be set to metered bypass. In this mode the rate app calculates the amount that is being bypassed to the tank and subtracts if from the flow meter counts. This results in only the actual amount going out the booms being subtracted from the tank amount.
Added Invert_Master on the Development branch. GitHub - SK21/AOG_RC at Development
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Thank you for working on that. That would make it easier to convert my sprayer to one of your rate controllers. It works perfect on my 3 point sprayer. Might be time to put it on my self propelled sprayer