# RBFM-AK Ultra-Low Flow Clamp-on Ultrasonic Meter

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> R&B Instrument Inc..

## Facts

- **Model:** RBFM-AK
- **Category:** Ultrasonic Flow Meter
- **Canonical page:** https://www.rbflowmeter.com/products/rbfm-ak-ultra-low-flow-clamp-on-ultrasonic-meter
- **Language:** en
- **Last updated:** 2026-10-18
- **Brand:** R&B Instrument Inc.

## Overview

Clamp-on ultrasonic meter for DN6–DN100 pipes measuring ultra-low liquid flow without pipe modification, with OLED display and 4–20mA/RS485 outputs.

## Description

### Product Overview

The RBFM-AK brings clamp-on ultrasonic measurement down to DN6 small pipes and ultra-low flow rates that thermal and turbine instruments struggle with. A sub-10 ps timing chip and magnetic-assist transducer alignment keep readings stable at 0.1–5.0 m/s.

The integrated unit needs no external transmitter: a 1.3" OLED shows flow, velocity, totalizers and signal quality, while RS485 Modbus and 4–20 mA connect straight to PLC or BMS.

## Specifications

| Parameter | Value |
| --- | --- |
| Diameter | DN6 – DN100 (OD φ9.53–φ110 mm; 1/4–4") |
| Accuracy | ±2.0% (0.3–5.0 m/s); repeatability 0.8% |
| Velocity | 0.1 – 5.0 m/s |
| Temperature | -10°C ~ +50°C (optional extended) |
| Output signal | RS485 Modbus RTU; 4–20 mA (≤600 Ω); optional OCT/relay alarm |
| Power supply | 24 VDC @3 W (220 VAC optional) |
| Protection | IP54 / IP65 |

## Key specifications

- Accuracy: ±2.0% (0.3–5.0 m/s), repeatability 0.8%
- Pipe size: DN6 ~ DN100 (OD φ9.53–φ110 mm)
- Output signal: RS485 Modbus RTU, 4-20mA, OCT/relay alarm (optional)

## Features

- Non-invasive clamp-on; no pipe cutting or pressure loss.
- Ultra-low flow sensitivity for small pipes DN6–DN12.
- Sub-10 ps timing chip with magnetic-assist transducer alignment.
- Compact integrated unit, no external transmitter required.
- 1.3" OLED shows flow, velocity, totalizers, signal and date.
- RS485 Modbus and 4–20 mA; optional OCT/relay alarms.

## Contact

For pricing, lead time and customization, contact R&B Instrument Inc. via the product page above.