The issue of the watt rotary actuator not closing under the 1000 psi oxygen stream due to insufficient return spring strength was corrected by adding an 80psi nitrogen line to the outlet port on the return side of the spring/piston assembly. This would essentially assist the spring in closing the ball valve.
Originally only one N2 line, controlled by a single solenoid, was used to open the rotary actuator which opened the ball valve. Now that we have two N2 lines but have not increased the digital output lines on our controller (or changed the software) we needed to implemented a 4-way solenoid valve. This valve will either supply N2 to open or N2 to close side of the ball valve depending on if the solenoid is energized or not.
This fix unfortunately is not all that pretty. We only had a 110VAC 4 way solenoid where as the rest of our system is 12VDC. To get around this issue we will use a 12VDC to 110VAC inverter to power the solenoid. The inverter will get its 12VDC from the control/driver board line that we previously used to drive the 12VDC solenoid that opened the ball valve.
The system still needs to be tested with the control electronics and in full 1000psi oxygen flow. The system was tested by Maggie and Brian using a straight 12V battery source and a 1000psi oxygen stream that was metered down to a small portion of normal and it worked fine.
The following pictures illustrate the new changes:
