Research on the optimization of evaluation methods for dust/toxin-removal capabilities of side-suction hoods in OHC facilities

This study addresses unreasonable capture velocities used in evaluating dust/toxin-removal efficiency of side-suction hoods adopted in occupational hazard control facilities. A combination of laboratory experiments and numerical simulations is employed to compare the diffusion patterns and capture velocities for side-suction hoods under different conditions. The results indicate that the initial dispersant velocities significantly impact the capture velocities of side-suction hoods. Specifically, the capture velocity for side-suction hoods was 0.12 m/s for an initial dispersant velocity of 0–0.40 m/s, 0.47 m/s for an initial velocity of 0.40–2.00 m/s, and 0.98 m/s for an initial velocity of 2.00–5.00 m/s, respectively. The dust capture efficiency of side-suction hoods was higher than that of chemical toxins, while the dust capture velocity was approximately 55.0 % that of chemical toxins. To address the challenge of undetectable capture velocities in certain scenarios, this study introduces the hood-face airflow velocity as a new indicator for evaluating the dust/toxin-removal capabilities of side-suction hoods based on an analysis of its relationship with the capture velocity. The results indicate that when the capture distance equals the equivalent hood diameter, the hood-face airflow velocity is evaluated as 0.66 m/s for an initial dispersant velocity of 0–0.40 m/s, 2.60 m/s for an initial velocity of 0.40–2.00 m/s, and 5.42 m/s for an initial velocity of 2.00–5.00 m/s, respectively. The findings of this study will provide useful theoretical guidance for the practical evaluation of the dust/toxin-removal performance of workplace side-suction hoods and for optimizing such evaluation methods.