Choosing the Right Water Flow Sensor for Your System

Picking the wrong flow sensor is one of the most common — and most expensive — mistakes we see in water metering projects. The right choice depends less on brand and more on three things: pipe size, what's flowing through it, and how accurate the reading needs to be. Here's how the main types in our catalogue compare.

Hall-effect sensors — best for small pipes, tight budgets

Hall-effect flow sensors (like our FLOWSNS-FS300A and FLOWSNS-YFS201) use a small spinning rotor and a magnetic pulse count to estimate flow. They're inexpensive, easy to install inline, and well suited to DN15–DN25 lines — household connections, small irrigation runs, or a single tap on a prepaid kit. The trade-off is that the spinning rotor wears over time and struggles with dirty or debris-heavy water, so they're not the right call for a borehole feed or anything with sediment.

RS485 turbine meters — for continuous monitoring at scale

Our RS485 Turbine Flow Meter reports over a proper industrial bus instead of a simple pulse, which matters once you're pulling data into an RTU or SCADA system rather than reading a dial by hand. Turbine meters handle higher flow rates than Hall-effect sensors and hold their accuracy better over long runtimes, making them a good fit for WSP distribution points and estate-level metering.

Electromagnetic flow meters — for non-invasive, high-accuracy readings

The Electromagnetic Flow Meter in our range has no moving parts at all — it measures flow using the voltage induced as conductive water passes through a magnetic field. That makes it the most accurate option we carry and the most resistant to wear, though it only works on conductive fluids (which ordinary water is) and costs more up front. It's the right choice when downtime for maintenance isn't an option, such as a bulk supply meter feeding a whole scheme.

Clamp-on meters — when you can't cut the pipe

Sometimes the pipe is already buried, pressurised, or simply not something you want to cut into. Our Clamp-On Flow Meters (portable and wall-mount) strap onto the outside of an existing pipe and measure flow ultrasonically, which is ideal for retrofits, audits, and leak-detection surveys where installing an inline sensor isn't practical.

A quick rule of thumb

• Single tap or small irrigation line, budget-conscious → Hall-effect
• Distribution point feeding an RTU or dashboard → RS485 turbine
• Bulk meter, high accuracy, minimal maintenance → Electromagnetic
• Existing pipe you can't modify → Clamp-on

Not sure which fits your setup? Request a quote and tell us your pipe size and use case — we'll point you at the right sensor rather than the most expensive one.