Near Intersection of I-35 & I-90 Southern Mn. | Ron - I haven't ever done this but off of the top of my head I would think it would be possible.
My thought is to utilize a Double Pole Double Throw (DPDT) relay. This relay could be wired so that the Fast Valve was always in the fully OFF position until application was desired. The relay would then throw a constant 12V to the control portion which would open the valve fully. This would effectively change the valve from one that could be closed, partially open or fully open (normal Fast Close operation) to one that is either fully closed or fully open (normal standard ON/OFF valve operation).
Generally this would not be done as it would be cheaper to buy an ON/OFF valve in the first place. However if you already have the Fast Close valve and want to utilize it as an ON/OFF, I think it should be possible.
The setup would have the flowmeter followed by a standard control valve and then the Fast Close valve (behaving like a standard ON/OFF valve) in line. The console would be programmed for STANDARD CONTROL (C-SD). In this setting, the control valve's position does not change when the unit is shut off at the ends. The only time the control valve moves is when the system is ON and the applied rate does not closely agree with the target rate. This means that when you turn the system back on, the control valve is in the approximate correct position and the system does not need to "hunt" up and down to find the correct position of the valve.
As long as we're talking about NH3 control and ON/OFF valves, I have setup up a B&H cultivator for NH3 application this year on my farm. Normally I would apply the NH3 in the Fall or Spring with a standard NH3 toolbar. This year due to economic factors last Fall (NH3 was extremely expensive if you didn't have the price locked in) and the weather this Spring, we decided to plant whenever possible and worry about the "N" later.
Since we had the B&H cultivator already, we decided to make it into an NH3 sidedresser. Rather than move the Accu-flow from the toolbar to the cultivator we decided to purchase a second Accuflow unit. On my old Accu-flow unit I have used a KZ ON/Off valve for several years without any problems. The control valve is the older Raven style with the blue cover. This too has worked very well with no problems.
Due to the good success I had with the KZ actuator/valve, I decided to go with the KZ replacement series on the new Accuflow. This replacement series is an actuator (motor/control circuit/drive) that bolts on in place of the Raven actuator. According to KZ, this series was created as an alternative to the Raven actuators that have been known to have moisture problems and failures.
So far the KZ replacement actuators seem to work fine. Time will tell if they are more reliable in the long run.
So Ron for you situation, an alternative to the relay idea would be to just buy the Raven Replacement actuator (On/Off type) from the KZ folks and bolt it onto your existing valve body.
Edited by tedbear 6/12/2011 09:33
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Applying NH3 at a low rate need help
