Flow indicator sensor that's cheaper and more robust than a flow meter?

[gomipile]

I'm speccing up a possible system that requires a water pump to be operated continuously for years. If the water flow stops completely in certain circumstances, immediate action might have to be taken to shut down the system properly.

I could tie an alarm to a flow meter, but I'm hoping that there's a cheaper and more durable type of sensor that just detects whether flow is above a general set limit.

[Lord Torath]

Is this system flow in pipes, or open channel flow? If it's open channel flow, you might be able to get away with a level switch of some sort, depending on the flow set up. For pipe flow, you're going to need some sort of a flow meter, I'm afraid. There are various types of flow meters, some much more expensive than others.

You might want to look into a disc pump if you don't want it damaged when the flow gets blocked:
DiscFlo Pump Demo (I am not affiliated with DiscFlo).

[gomipile]

Is this system flow in pipes, or open channel flow? If it's open channel flow, you might be able to get away with a level switch of some sort, depending on the flow set up. For pipe flow, you're going to need some sort of a flow meter, I'm afraid. There are various types of flow meters, some much more expensive than others.

You might want to look into a disc pump if you don't want it damaged when the flow gets blocked:
DiscFlo Pump Demo (I am not affiliated with DiscFlo).

It's all in pipes. I was thinking that there might be something like a solid state ultrasonic flow meter that's put together relatively cheaply without consideration for the ability to calibrate it precisely. The target application wouldn't require precise calibration or precision and accuracy over a whole range of flow rates. It wouldn't have to be calibrated by the manufacturer or be made with calibration over a range in mind. Thus, I figured such a device could be made far more cheaply than anything designed for actually metering flow.