When stations are running, the Flow Monitor continuously checks the actual flow from the sensor(s) against the combined learned flow of the stations, including the overflow and underflow percentages allowed in the Flow Zone. It also checks this flow against the higher level Flow Zone limits, and MainSafe™ limits if applicable.
If the total amount caused by running stations is exceeded beyond the permissible station delay periods, the controller pauses all stations (shutting off the P/MV) in the Flow Zone. It waits 60 seconds after the stations are paused, for the flow to drop to near 0.
If flow does drop to near zero when the Flow Zone is paused, the controller then begins running the stations that were running at the time of the alarm, one by one, to test which station(s) are causing the high flow conditions. The controller will mark failed stations in the logs, and continue irrigating with stations that pass the individual flow tests.
If flow does not drop substantially during the diagnostic pause period, the controller determines there is a Mainline Overflow, and will not resume irrigating or perform further diagnostics. It will remain shut down for the period specified in the Alarm Clear Delay setting on the Flow Zones screen.
When flow alarms are detected at the Flow Zone or MainSafe level, they can be cleared from the Flow menu, Clear Flow Alarms. A shortcut key is also available to Clear Flow Alarms when these conditions are detected, after View Messages has been selected.
If the actual flow exceeds the Maximum Flow allowance for the Flow Zone, and continues for the time set in the Alarm Delay, the Flow Zone alarms and shuts down without further diagnostics. The same applies to MainSafe zones, if applicable. The controller assumes the overflow condition is the result of a mainline failure, above the station level.
If flow exceeds any Unscheduled Flow allowance when no stations are supposed to be running, and continues for the time set in the Alarm Delay, the Flow Zone and/or MainSafe zone will also be shut down.