ISO 13347-2:2025

Overview

ISO 13347-2:2025 - Fans: Reverberant room method specifies how to determine fan sound power levels from sound pressure levels measured in a reverberant room under standardized laboratory conditions. The second edition updates procedures for laboratory testing of airborne acoustic emissions from fans (including fan + ancillary devices such as roof cowls, dampers or silencers where applicable). It is limited to airborne sound - vibration effects are not measured - and is intended for controlled laboratory environments rather than in‑situ field measurement.

Key topics and technical requirements

• Test principle: Measure sound pressure in a qualified reverberant room and calculate sound power level (Lw) for fans in one‑third octave and one octave bands.
• Room qualification: Requirements and procedures for qualifying reverberant rooms (Annex A normative for broadband sources; Annex B informative for tonal/narrow‑band sources).
• Instrumentation & set‑ups: Specification of measurement instrumentation, microphone travel, mounting methods and ducting arrangements tailored to fan geometry and airflow.
• Background & corrections: Procedures for background noise correction, RSS calibration, inlet/outlet end corrections and resulting calculations (including Lw computation).
• Scope limits: Equipment under test should occupy < 2% of room volume for reverberant field tests. Low‑power domestic fans (≤ 3 kW) may reference IEC 60704‑2‑7.
• Annex C: Informative guidance for testing fans with attached ancillary items.
• Excluded aspects: Vibration measurement and site (in‑field) measurements are outside the scope.

Applications and practical value

• Compare acoustic performance between fan models and sizes.
• Verify compliance with specified sound emission limits.
• Provide sound power data for noise prediction and system acoustic design (HVAC, ventilation, industrial fans).
• Support product development aimed at quieter fans and acoustic optimization of fan + silencer combinations.
• Generate standardized data used in procurement, regulatory assessment and acoustic modeling.

Who should use this standard

• Acoustic engineers and test laboratories performing fan noise measurements.
• HVAC and ventilation designers requiring standardized fan noise data.
• Fan manufacturers validating product sound performance.
• Certification bodies and consultants involved in noise compliance and prediction.

Related standards

• ISO 13347-1:2025 (general overview)
• ISO 13349-1 (fan definitions)
• ISO 5136 (in‑duct method)
• ISO 10302-1 (small fans)
• ISO 3741 / ISO 3743 (reverberation room precision methods)
• ISO 5801 (fan performance test airways)
• IEC 60704‑2‑7 (low‑power fan reference)

Keywords: ISO 13347-2:2025, reverberant room method, fan sound power levels, acoustic performance, laboratory measurement, fan noise testing.