Near Intersection of I-35 & I-90 Southern Mn. | I'm not positive anymore.
The so called Fast Close valve is often used with NH3 where it acts as both the regulating and ON/OFF valve. The idea is to save money by only having a single valve instead of a Standard Control valve and a separate ON/OFF valve. Sine the Fast close valve needs to close the ball rapidly when the system is shut off, there is no gearing involved between the motor and the ball. This means for control where a very slight movement is needed the motor is hard to control and move the ball just a small amount. To accomplish this the Raven 440 when set up for a Fast Close valve will send extremely short shots to move the ball for control. Actually if the system detects that the applied rate is a little low and needs to open the ball slightly, the system will send maybe two short shots to open it further followed by a reverse polarity shot to stop it. This keeps the ball from going too far.
You ask about zero speed off. I believe this is possible with some of the Raven consoles that work with hydraulic valves to control the bed in a granular application. I don't believe that zero speed off is an option with a standard 440. |
Raven 440 zero speed shut off
