Background:
Flow stops were added to G3 tunnels to hold water in the tunnel when it goes into hold. The first control was a shuttle valve that would operate off the same air supply as the main water valve and is spring loaded.
In PulseFlow machines, when the main water is on for PulseFlow, the shuttle valve shifts against the spring and feeds a 1/4" air line to all the flow stops and the main water inlet valve.
If a FlowStop does not open and you flow water into the CBW, then the machine will flood. "What goes in must come out", so check the flow stop function if flooding is occurring. This can be an intermittent problem. To check the health of the FlowStops proceed as follows.Shuttle valves for Flow Stops:
The first step is to locate the Parker Shuttle Valve along the side of the tunnel. See below circled in red. You may have a shuttle valve on each mod section, so you may have more than one.
Once you have located the first shuttle valve (closest to module 1), place your hand in front of the two exhaust ports on the side of the valve as indicated in image.If you feel continuous air flow through the exhaust ports, then we know that air is flowing when it shouldn’t be and this could be caused by a FlowStop piston cup leak. If the 1st Shuttle Valve is functioning correctly (only exhausting when the valve is moving) then move on to the others if you have any.If one of the shuttle valves is continuously exhausting air then there may be a piston seal leak on one of the FlowStop Valves below the weir box.
To confirm that it is a seal leak, walk over to the flow stops on the other side of the tunnel. Look for the air cylinder pictured below.
Disconnect the Air Hose at inlet 2. While NOT in PulseFlow there should be no air flowing out of the cylinder but there should be air flowing out of the tubing.
Pilot valves:
There should never be any air flowing out of any pilot valves shown below unless it has just opened or closed. You can use a cup of water to test for leaks on these. A small leak matters! If your pilot valve is leaking it may be that your piston seal on the FlowNot is leaking air. If so you can rebuild the valve with the following kit: KZRKDVDA01
More backgound:The air lines are tee'd at the flow stop air cylinder. The flow stop air cylinder is air to operate both ways. When main water is off the spring in the shuttle valve shifts the spool to send air out to close all the flow stops, through one 1/4" line that is tee'd at the air cylinders.
In fall of 2006 we started adding a shuttle valve per CBW section. The problem with the single shuttle valve was when the air cylinder piston cups fail. The 1/4" air tube could not feed the leak and also keep the other cylinders moving. So multiple flow stops would stay closed and the machine would overflow water from the weirs.
The tell tale for the piston cup failure is the shuttle valve leaking air from an exhaust port. When the cups fail and bypass you will get air always coming out of the exhaust port on the shuttle valve.
You will have to isolate the cylinder that is leaking by removing the air tubing at each cylinder.
A few assembly number to help.
G64DV005 = weir to sewer = mod one and mod last
G64DV006 = weir to Flow Splitter
G64DV007 = Flow Not to sewer = mod two
The shuttle valve used in this application is 96N0011H. The same shuttle valve is used on the G4 CBW.
