but if your hose fall up, you will have flow(but bigger flow). So you need to report error if flow is to big or to small(pump doesn't work).
They can generally be configured to alarm if the flow is too low OR too high. It expects the flow to be inside a certain window. In this sense it will detect a broken fitting, etc.
The only catch is the window needs to be large enough that it does not give false alarms, which can be tricky if you are modulating the pump over a broad range of flow rates.
In my opinion using lean detect is pretty comprehensive.
The only thing I wish could be added is an "off delay" where the warning light stays on for an additional (configurable) amount of time after a lean even ocurrs (ie it stays on for 10 seconds before resetting).
