Evaluation of a Multi-Point Monitoring System for Temporal and Spatial Variations in Formaldehyde During a New-Formulation Adhesive Process for Building Materials

This study investigated temporal and spatial variations in formaldehyde (HCHO) concentrations during a hot-pressing process simulating the manufacture of wood-based building materials and evaluated a compact multi-point HCHO monitoring system for process monitoring. The system consisted of four monitoring nodes measuring HCHO, temperature, and relative humidity, together with a Wi-Fi-based web platform for continuous data acquisition at 1 s intervals. Six hot-pressing tests were conducted using a formaldehyde scavenger at 0, 5, and 10 wt%. Monitors #1 and #2 were installed inside the hot-press enclosure, whereas #3 and #4 were positioned near the exhaust duct. A commercial HCHO monitor (HFX205, Ref) was installed near the exhaust outlet for comparison. HCHO concentrations generally increased during hot pressing, with more pronounced changes near the exhaust duct than inside the enclosure. Although the commercial monitor showed higher absolute concentrations, its temporal trend was similar to those of the developed monitors near the exhaust. No consistent reduction in HCHO concentration was observed with increasing scavenger loading. These results highlight the importance of sensor location and exhaust configuration and support the potential use of the developed system as a supplementary tool for multi-point process monitoring.