A European air quality solutions provider needed to reduce noise in their air purifier below 40 dB(A) — without compromising airflow performance.
The air purifier draws air at ceiling level and expels clean air at floor level. It is equipped with coarse, fine, and gas filters, with a fan mounted in the lower section. Airflow capacity: 120–300 m³/h.
At the lowest fan speed, the noise level measured 42.7 dB(A) Leq — above the threshold for a comfortable indoor environment. The goal was to get below 40 dB(A) without reducing airflow.
Fan vibrations and airborne noise were transmitted through the sheet metal construction of the lower section, creating audible noise even at the lowest RPM.
Reduce noise below 40 dB(A) at minimum speed — and ideally achieve a significant reduction at maximum speed — without affecting airflow or thermal performance.
Sontech analyzed the noise sources and proposed a combination of vibration damping foil, self-adhesive sound absorbents, and heavy insulation mats — delivered pre-cut and die-cut for easy installation.
| Location | Material | Area |
|---|---|---|
| Front, lower section | Dämpfolie 9 | 0.16 m² |
| Front, lower section | Tecnocell 25 SA | 0.10 m² |
| Front, lower section | Tecnocell 64 SA | 0.04 m² |
| Rear, lower section | Dämpfolie 9 | 0.20 m² |
| Rear, lower section | Tecnocell 38 SA | 0.13 m² |
| Rear, lower section | Isolermatta 7 | 0.10 m² |
Measured in a 5.8 × 6.8 m room (ceiling height 2.4 m). Microphone at 1.65 m height, 1 m from the unit. Equivalent sound level measured at both max and min fan speed.
Bitumen-based vibration damping foil. Applied directly to sheet metal surfaces to reduce structure-borne noise and resonances.
Self-adhesive sound absorbent (UL94 HF1 rated). Available in multiple thicknesses (25, 38, 64 mm) for optimal absorption tuning.
Bitumen-based insulation mat (7.5 kg/m²). Provides effective sound insulation through its mass and dampens transmission through panels.
All materials were delivered pre-cut and die-cut to drawing — ready for direct assembly on the customer’s production line.
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