AFRISO STM225 Portable Laser Dust Monitor for Flue Gas Particulate Measurement

Overview

The AFRISO STM225 is a portable, field-deployable flue gas particulate monitor engineered for regulatory-grade measurement of dust mass concentration in industrial exhaust streams. It employs a dual-beam laser scattering principle—utilizing simultaneous 90° side-scatter and forward-scatter detection—to distinguish fine-mode (sub-10 µm) and coarse-mode (10–100 µm) particulates within the same sampling event. This optical architecture eliminates reliance on empirical calibration curves or particle-size assumptions, delivering direct, real-time mass concentration output (mg/m³) traceable to NIST-traceable reference aerosols. The instrument operates in accordance with EN 15267-3 requirements for quality-assured automated monitoring systems and supports QAL1 (Quality Assurance Level 1) validation protocols when integrated into CEMS infrastructure. Designed for intermittent or spot-check deployment, the STM225 performs autonomous 15-minute measurement cycles, computing time-weighted average concentrations with automatic zero-point verification upon startup using built-in air filtration and internal reference photodiodes.

Key Features

• Dual-beam laser photometric detection with independent optical chambers for fine and coarse particulate discrimination
• 5.7″ high-resolution color touchscreen interface supporting intuitive calibration navigation, data logging, and configuration management
• Integrated electro-heated sampling probe (280 mm or 400 mm options) with Teflon-coated stainless steel tip and condensate-resistant thermal management
• Bluetooth 5.0 wireless synchronization with AFRISO M60 flue gas analyzer—enabling concurrent O₂, CO, CO_H₂, and NO_x measurement alongside particulate concentration
• Onboard air-zero calibration routine initiated automatically at power-on, utilizing certified air filter cartridges (5-pack supplied)
• Rugged PE polymer carrying case with ergonomic shoulder strap, impact-resistant housing, and modular accessory layout for field portability
• Low-maintenance optical path design: laser diode lifetime exceeds 50,000 hours; no consumable optics or replaceable light sources required

Sample Compatibility & Compliance

The STM225 is validated for use across solid-fuel combustion sources including biomass boilers, wood pellet furnaces, coal-fired stokers, and municipal waste incinerators. Its heated probe and dual-chamber optical design mitigate condensation interference and particle re-entrainment effects common in low-temperature, high-humidity flue streams. All measurement outputs comply with EN 14181 (periodic quality assurance of automated measuring systems), ISO 12141 (determination of particulate matter in flue gases), and ASTM D6216 (standard test method for determination of particulate matter emissions from stationary sources). When deployed as part of a full CEMS stack configuration, the STM225 satisfies Tier 2 performance criteria under EPA Method 5 and EU BREF BAT conclusions for dust monitoring. Data integrity meets GLP/GMP audit trail requirements via timestamped, non-erasable internal memory logs compliant with FDA 21 CFR Part 11 electronic record provisions.

Software & Data Management

Data acquisition and reporting are managed through the embedded firmware v3.2, supporting CSV export via USB and real-time telemetry over Bluetooth to the AFRISO Connect mobile application (iOS/Android). Field operators may configure measurement intervals, set alarm thresholds (e.g., >150 mg/m³), and assign location metadata to each measurement series. All raw scatter intensity waveforms, temperature-compensated photodiode readings, and calculated averages are retained internally for ≥10,000 measurement records. For laboratory integration, the STM225 exports ASCII-formatted reports compatible with LIMS platforms and supports optional OPC UA server configuration for SCADA-level interoperability. Firmware updates are delivered via signed binary packages with SHA-256 hash verification to ensure cryptographic integrity.

Applications

• Regulatory compliance verification for dust emissions from biomass heating systems (EN 303-5, DIN 18893)
• Commissioning and periodic performance testing of electrostatic precipitators (ESPs) and fabric filters
• Stack testing during boiler tune-ups and combustion optimization studies
• Pre-compliance screening prior to formal QAL2/QAL3 certification of permanent CEMS installations
• Research applications involving particle size distribution inference via dual-angle scatter ratio analysis
• Mobile source audits for industrial clusters where fixed-stack monitors are impractical

FAQ

Does the STM225 require annual recalibration against gravimetric standards?
No—per EN 15267-3 Annex C, the STM225 qualifies for QAL1 certification with biennial verification using certified reference aerosols. On-site zero/span checks using clean air and polydisperse test dust (ISO 12103-1 A2) are recommended quarterly.
Can the STM225 operate continuously for >24 hours without interruption?
Yes—the instrument supports unattended operation up to 72 hours on AC power. Battery backup is not included; external 12 V DC UPS units may be connected via the auxiliary power port.
Is the M60 flue gas analyzer mandatory for STM225 functionality?
No—the STM225 operates independently as a standalone particulate monitor. Bluetooth pairing with the M60 is optional and enhances data correlation but does not affect core dust measurement capability.
What maintenance intervals apply to the heated probe and internal optics?
The electro-heated probe requires visual inspection before each use; cleaning with supplied cotton swabs and PTFE wipes is advised after every 10 sampling events. Internal optics require no user-accessible servicing; optical alignment stability is verified during QAL2 procedures.
How is humidity compensation handled in high-moisture flue gases?
The STM225 uses real-time temperature and relative humidity inputs from its integrated probe thermistor and capacitive RH sensor to apply Mie-theory-based refractive index correction factors to the scatter signal—validated per ISO 12141 Annex B.