Posted 4/14/2018 08:28 (#6707914 - in reply to #6707836) Subject: RE: Raven NH3 Parts
Southern Minnesota Between Freeborn & Wells
Any Raven dealer should be able to get these parts for you. I would test the pieces individually if you are having problems.
With the system fully drained you can perform some tests - Be careful as NH3 can get trapped in various places and surprise you. The ON/OFF valve should go fully closed and nearly wide open when the Master and/or Section switch is cycled. The ball valve only turns about 80 degrees rather than the 90 degrees you might expect.
The standard control valve can be tested as follows: The display should be set for Standard Control (not Fast which may show as C-F or Fast Close which may show as C-FC). Turn ON the Master and Boom sections switches, with the Rate1/Rate2/MAN switch in MANual, push and hold the Inc/Dec switch UP which should cause the ball valve to open and eventually stop. It should be mostly open but not 100%. Push and hold the switch DOWN which should cause the control valve to go closed and stop. Once the valve is fully open or fully closed, it should take around 8 seconds to go completely the other direction.
A common problem with for NH3 is to use the wrong meter cal. Use the meter cal for NH3 (around 170 or so) if you wish to enter the target rate as Pounds of Actual Nitrogen. This is for a Raven controller. Other situations may be different.
The flow meter can be disassembled. Remove it from the system (again be careful for trapped NH3) and remove the snap ring on the end with the adjustment nut. The housing and turbine can then be removed. Inspect the turbine shaft for wear or debris. If the NH3 tanks have been run empty much there will likely be excessive wear. Also check to determine if the turbine has been rubbing on the outside of the housing due to sloppiness. Many flow meter problems come from running the tanks too low which introduces vapor in to the system and the turbine spins at excessive speed with no lubrication. It is also subject to a "water hammer" effect which is not desirable. Reassemble the flow meter and shake it. You should hear the turbine rattle back and forth. There should be a slight amount of slop so the turbine can turn easily. If you shoot a short shot of air into the flow meter, you should see the turbine spin and gradually coast to a stop.
The KZ company makes a Replacement motor for both the Raven ON/OFF and Control Valves. It bolts on the original bracket and has the proper connectors to mate with the Raven harness. I had these on my last NH3 bar since they do not seem to have the moisture problem that certain Raven motors had.