QAL Certified Tribo Probe for Online Dust Monitoring

Online Dust Monitoring in Ducts with Tribo-Electric Probes

One proven principle for online dust monitoring in ducts is the tribo-electric probe. These probes have long been used for process monitoring in filter and dust separation systems. The measuring principle is based on the interaction of particles with the probe—either by contact or proximity—resulting in a charge. The generated DC and AC signals are interpreted using advanced algorithms and converted into an output signal proportional to the amount of dust. When combined with flow data, a dust concentration can be determined. Tribo-electric probes require very little maintenance; during service checks, basic inspection and cleaning are typically sufficient.

Model S305QAL for Continuous Dust Emission Monitoring

In many applications, the S305QAL model is highly suitable for continuous dust emission monitoring. This probe is QAL1 certified for the ranges 0–7.5, 0–15, and 0–100 mg/m³. It features 2 relay outputs, an analog 4–20 mA output, and Modbus RTU. The instrument also includes a 4–20 mA input for integrating flow measurements to enable proper flow-compensated concentration readings.

Collaboration with Accredited Labs and Quality Control

In collaboration with an accredited emissions testing firm, QAL2 testing and the Annual Surveillance Test (AST) can be conducted. For AST, a reference signal generator ("calibrator") can be used to simulate a known signal.

QAL3 checks—zero and span verifications—are performed automatically every 24 hours by the instrument. Due to continued development of the tribo-electric probe technology, it is now possible to perform highly accurate and continuous dust emission measurements.