F3RO · Fixed flow

Clip-on flow with pulse and relay outputs.

The pFlow F3RO clip-on ultrasonic flow meter uses the ultrasonic transit-time principle combined with Gentos’ flow algorithm.

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At a glance

What F3RO does, in plain words.

What it measures: Liquid flow; How much liquid moves through the pipe.
How it installs: Clamp-on; Sensors fit on the outside of the pipe, so the pipe stays closed.
How it connects: Pulse / relay; Pulse and relay outputs, wired to a counter or controller.
Pipe sizes: DN20–DN80; DN is the nominal pipe size, roughly the inside diameter in millimetres.

Why F3RO

F3RO in short.

The pFlow F3RO clip-on ultrasonic flow meter uses the ultrasonic transit-time principle combined with Gentos’ flow algorithm. It is easy to install and monitors water flow conveniently, with pulse (OCT) and relay outputs.

Where it is used

Modern agricultural irrigation
Garden irrigation
Seawater desalination
Desalination technology
Residential water
Washing industries
HVAC

F3RO · 2026 product catalog

How it works

Sound with the flow arrives sooner.

Two sensors on the same side of the pipe take turns sending sound through the water. Sound travelling with the flow arrives slightly sooner than sound travelling against it; the meter turns that time difference into flow, which is why it needs to know your pipe.

How clamp-on ultrasonic measurement works →

Pipe & installation

What the meter needs to know about your pipe.

These are set up on the meter after installation. Pipe size and transducer type are decided when ordering.

Pipe & installation guide pipe materials, sizes, setup checklist

Stainless steel · 2″ example

A smooth metal surface. Clean the spot, add coupling gel, then clamp the sensor on.

60.3mmacross the outside

2.8mmwall thickness

54.8mmacross the inside

Pipe sizes are names, not measurements: a 2″ pipe is 2.375″ across.

The meter needs Pipe size Wall thickness Material: Stainless steel

Technical details standards, OD / ID, both units

Standard: ASME B36.19 · 2″ Sch 10S
Outside diameter (OD): 2.375″ (60.33 mm)
Wall: 0.109″ (2.77 mm)
Inside diameter (ID): 2.157″ (54.79 mm)
Meter parameters: OD · wall · material

This guide shows what a clamp-on meter needs to know about a pipe. It does not mean every model fits every pipe: check the specifications below or ask an engineer.

Specifications

Check the fit before you specify.

The short version is above. These are the specifications published for F3RO; values that are still being checked are left out.

Performance

Flow velocity: 0.03–5.0 m/s (0.1–16 ft/s)
Pipe sizes: DN20, DN25, DN32, DN40, DN50, DN65, DN80
Accuracy: ±2% of reading (0.3–5 m/s)
Repeatability: 0.2%
Pipe material: Stainless steel, carbon steel, PVC, copper

Function

Pulse output: 0–9999 Hz, OCT, adjustable frequency limits
Relay output: Max. 1 Hz, 1 A at 125 VAC or 2 A at 30 VDC
Power supply: 10–36 VDC, 500 mA max.

Physical

Ambient temperature: −10 °C to 50 °C (14 °F to 122 °F)
Transducer temperature: 0 °C to 60 °C (32 °F to 140 °F)
Ingress protection: IP54
Transducer cable: φ5 six-core cable, 2 m (6.6 ft) standard

Need a value that is not listed, or the datasheet for your configuration? Ask an engineer.

What these terms mean

DN: Nominal pipe size, roughly the inside diameter in millimetres (DN50 ≈ 50 mm).
Clamp-on: Sensors strap to the outside of the pipe. No cutting, no shutdown for installation.
PoE: Power over Ethernet: one network cable carries power and data.
LoRaWAN: Long-range, low-power wireless. Readings travel through a gateway to a network server.
Modbus RS485: A wired connection widely used by building and industrial control systems.
4–20 mA: An analogue signal where the current represents the reading.