Near Intersection of I-35 & I-90 Southern Mn. | wffoker - 6/21/2026 16:00
Can a rate controller setup from an anhydrous bar be used for 28% ? It has raven scs440 and flow meter and valve it looks like. Not sure if the valves and flow meter would be same
Could the valves and flow meter be the same? The answer is broadly yes, but it is rarely done for several reasons. I will attempt to explain how the systems work.
Since your rig is is being used for NH3, your flow meter and valves would be the type made of metal. Although metal valves are not necessary for 28%, they can be used. The heat exchanger would not be used since 28% will remain a liquid at normal temperatures and pressures. The purpose of the heat exchanger is an attempt to keep the NH3 in a liquid state so the flow meter can accurately measure it.
For 28% only, a plastic shell flow meter can be used. The internal parts for both the metal (often RFM60S) and the metal (RFM60) are the same. Generally this would be the case for a 28% only machine since the plastic style is cheaper.
With a Raven 440 and NH3, the flow meter must be metal as mentioned above, however, there are two choices for the valve arrangement. This is often confusing to many.
The oldest and best method is to use a two valve system where the first valve is a metal ball valve that controls the rate. It is geared to move quite slowly (8 seconds). It is followed by another electric ball valve referred to as an On/Off valve. This valve moves rapidly, its only purpose is to turn the flow ON/OFF. The Raven 440 must be set to Standard Control. During operation, the control valve moves slowly in response to a change in ground speed or rate.
When the Master switch is turned from ON to OFF, the ON/OFF valve changes from fully open to fully closed. This means when turning around on the headlands, the ON/OFF valve goes from fully open to fully closed but the control valve remains in its present position which should be appropriate when the application resumes when the Master switch is turned ON. This results in good control since the control valve moves slowly and only when the ON/OFF valve is open.
The other cheaper alternative is to use a single valve to handle both the rate and ON/OFF duties. This is called a Fast Close valve. It is not geared down because it must move quickly to stop the flow on the Headlands. When application resumes, it must open rather quickly at first until the rate exceeds the desired rate, then stop and reverse slightly so as not to over apply. This can work but is not desirable. The ONLY advantage is this arrangement is that it is somewhat cheaper. The Raven 440 must be set to Fast Close so that it can attempt to control this situation correctly.
From your description, I believe you have the later Fast Close arrangement for NH3 so those components can work with a liquid like 28% however this is generally not done.
Generally a 28% system would use either a plastic flow meter although the metal one could be used followed by a butterfly type plastic control valve followed by one or several ON/OFF valves. This would give better control and the ability to have the rig setup in sections.
This is the situation the other poster was referring to when they mentioned needing to change the setup in the Raven 440.
So you could disassemble the NH3 bar and reuse the metal flow meter and valves for 28% but the result might be less than desirable. I would not recommend it.
Although more expensive, I would leave the NH3 bat as is and purchase a plastic based flow meter of the appropriate size, a butterfly control valve and one or several ON/OFF valves for the 28% rig. If you are abandoning NH3, the metal flow meter could be used with 28% although the internal components might have been damaged due to running the NH3 on vapor.
Edited by tedbear 6/22/2026 06:28
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Raven rate controller
