PSI - Issue 77

Alexander Backa et al. / Procedia Structural Integrity 77 (2026) 143–151 A. Backa et al. / Structural Integrity Procedia 00 (2026) 000 – 000

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system settings were kept unchanged. The chimney draft remained stable at 12 ± 2 Pa, as specified by STN EN 16510 1:2023. A schematic representation of the test setup, including the combustion unit, is shown in Figure 1.

Fig. 1. Diagram of the measurement setup.

2.3. Sampling methodology A unified sampling system was developed to collect particulate matter, combining in-situ extraction with external measurement capabilities. The probe was mounted on a movable slider mechanism for precise alignment within the combustion zone (Fig. 2). The sampling tip had a 6 mm internal diameter. To avoid distortion of temperature data from thermal radiation, a thermocouple protected by a fine metallic mesh was installed directly at the probe entrance. A corrugated, flexible hose was attached to the probe to allow for easy repositioning during experiments, leading to a rigid metal pipe with a 22 mm inner diameter. The system included a pitot tube, a gravimetric filter unit, and an FVAD 15 S120 flow sensor. These instruments provided key input for fan calibration before each PM collection cycle. An exhaust fan, connected to the outlet via a frequency-controlled motor, maintained airflow through the setup. Each sampling interval lasted 5 minutes. During this time, the pitot tube registered airflow velocities ranging from 1.5 to 1.6 m/s within the main sampling pipe. The air volume drawn through the system was maintained consistently throughout all test points.