AI generated- 0–250 m
- from the sensor in both directions
- 125–1875 Hz
- 15 frequency bands
- 2 pipes
- per AX-2
- IP67
- protection rating
Listens to the pipe without a leakage wire
Sonitus detects leaks in district heating and cooling networks from changes in the sound and vibration of the pipe. Sensitive accelerometers are attached directly to the steel pipe, and the method uses no leakage wire. One sensor hears 0–250 m of pipe in both directions, up to 500 m in total.
The AX-2 analyser converts the signals of two sensors into 15 frequency bands between 125 and 1875 Hz. The GW-102 gateway handles communication over LTE Cat-M1, NB-IoT or GSM/GPRS and powers up to two AX-2 units over an encrypted RS485 bus, up to 500 m away. The gateway can therefore sit above ground in a cabinet, with the AX-2 in the chamber next to the pipe.
Readings and alarms are shown in the monitoring system. When two modules are on the same pipe no more than 500 m apart, they form a section: the system compares the sensors’ readings and estimates where along the section the leak is. This narrows the area to search on site with a ground microphone or a thermal camera.
On site, a phone connects to the GW-102 over Bluetooth. Settings and readings are at hand, and you can record the sound of the pipe and listen to it. This helps find a place for the sensor where a pump, valve or filter does not drown out the sound of a leak. Settings can also be changed remotely.
- The sensor is attached to the steel pipe with a magnet or a welded M6 stud. The same welding equipment also attaches Fixbox measuring points.
- Power 9–30 V from a mains adapter or battery. With the optional internal battery, a solar panel connects directly, and the battery keeps the module online overnight.
- Transient and lightning surge protection, and low current consumption: 50 mA nominal.
- CE and RoHS marked.
| Range from the sensor | 0–250 m in both directions (500 m pipe) |
|---|---|
| Frequency range | 125–1875 Hz, 15 bands |
| Measuring range | −80…0 dB |
| Sensors | 2 accelerometers per AX-2 |
| GW-102 ports | 2 × RS485, encrypted |
|---|---|
| Cable GW-102 – AX-2 | up to 500 m |
| Cable AX-2 – sensor | up to 2 m |
| Sensor mounting | Magnet or welded M6 stud |
| Communication | LTE Cat-M1, NB-IoT, GSM/GPRS |
|---|---|
| Locally | Bluetooth |
| Voltage | 9–30 V (14.4 V) |
| Current | 50 mA nominal (max 500 mA) |
| Internal battery | 3.7 V Li-ion (option) |
| Solar panel | Directly, with the internal battery |
| Alarm input | Open / close |
|---|---|
| Alarm output | 48 V / 200 mA |
| LED indication | Yes |
| Protection rating | IP67, sensors IP68 |
| GW-102 (W × H × D) | 150 × 55 × 80 mm |
| AX-2 (W × H × D) | 125 × 40 × 32 mm |
| Sensor housing | Stainless steel 316L, −40…+120 °C |
How acoustic leak detection works
Sound travels far in a steel pipe, so a single reading does not yet indicate a leak. The alarm is based on a change from the site’s own background noise.
Baseline
A week of readings sets the site’s background noise, for example −75 dB. The scale runs from −80 dB (quietest) to 0 dB.
Alarm limit
A new, stable level that rises more than a third of the way from the baseline to 0 dB most likely indicates a leak: with a −75 dB baseline, above −50 dB.
Location
On a section, the system compares the frequency bands of two sensors and estimates the distance from one end. Small leaks usually show in the lowest bands.
Before analysing a section, check that the noise is not made in the chamber itself, for example by a leaking valve.
The Sonitus set
One set monitors the two pipes in a chamber, supply and return. Supply goes on sensor 1 and return on sensor 2.
- GW-102
- Gateway. Handles communication and powers up to two AX-2 units. Connections for a communication and a GPS antenna.
- AX-2
- Acoustic signal analyser. Converts the signals of two sensors into 15 frequency bands. Programmed at the factory.
- Sensors
- Two stainless steel accelerometers, IP68. Mounted with a magnet or a welded M6 stud.
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