Overview
ISO 13347-1:2004 - Industrial fans - Determination of fan sound power levels under standardized laboratory conditions - Part 1: General overview - gives a structured, consensus-based framework for measuring and reporting the acoustic performance of industrial fans in laboratory settings. The standard defines terminology, measurement uncertainty, instrumentation, test and installation conditions (types A–D), and reporting requirements for determining fan sound power levels (in octave and one‑third octave bands). It applies to bare fans and to fans combined with ancillary devices (roof cowls, dampers, silencers) and is intended for ducted and non-ducted applications in controlled test environments (not site measurements).
Key Topics and Requirements
- Scope and definitions: standard air, inlet/outlet/casing sound power levels, ducted vs non‑ducted fans, reference points and fan areas.
- Frequency range of interest: octave bands centered 63 Hz–8 000 Hz and one‑third octave bands 50 Hz–10 000 Hz (extensions allowed where justified).
- Measurement methods overview: links to detailed Part 2 (reverberant room), Part 3 (enveloping surface), and Part 4 (sound intensity).
- Installation & operating conditions: standardized fan mounting, duct terminations, and flow conditions to ensure repeatable acoustic data.
- Instrumentation & calibration: microphone arrays, reference sound sources and calibration procedures (see Annex F and ISO 6926).
- Uncertainty & corrections: procedures for estimating measurement uncertainty (Annex E) and for correcting end reflections, speed changes and air property differences (Annexes A, B, C).
- Reporting & calculations: required test data, one‑third/octave band results, overall and A‑weighted sound power levels, and recommended symbols (e.g., LWA(A,in), LWA(D,cas)).
Note: blade passage frequency (BPF) is defined for tonal analysis: BPF = x * n / 60 (Hz), where x = blade count and n = rev/min.
Practical Applications
- Product development: acoustic benchmarking, noise reduction design and verification for impellers, casings and ancillary devices.
- Compliance & selection: verifying that fan models meet customer or regulatory sound limits and supporting selection of silencers or acoustic enclosures.
- Noise prediction: providing sound power input data for room and duct noise propagation models and HVAC noise assessments.
- Test laboratories & certification: standardizes laboratory procedures so results are comparable across manufacturers and labs.
Who Uses This Standard
- Fan manufacturers and R&D teams
- HVAC and mechanical engineers
- Acoustic consultants and test laboratories
- Certification bodies and procurement specialists
Related Standards
- ISO 13347-2, -3, -4 (detailed measurement methods)
- ISO 5801 (fan airflow test conditions)
- ISO 3741/3744/3745 (sound power in rooms)
- ISO 5136 (in-duct method)
- ISO 9614 (sound intensity) and ISO 6926 (reference sources)
ISO 13347-1:2004 is the essential overview for anyone working on fan noise measurement, acoustic performance reporting, and standardized laboratory testing of industrial fans.
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