Overview
EN ISO 21904-2:2020 - Health and safety in welding and allied processes - Equipment for capture and separation of welding fume - Part 2: Requirements for testing and marking of separation efficiency - specifies a laboratory test method to verify whether welding fume capture and separation equipment meets stated separation efficiency requirements. The standard covers testing procedure, measurement and calculation principles, and requirements for marking equipment with performance results. It applies to equipment manufactured after publication and does not apply to filter cartridges tested independently of the equipment.
Key topics and technical requirements
- Test principle: Charge the separation equipment with welding fume from a controlled welding fume source and measure fume concentrations in incoming and exhausted air to determine separation efficiency.
- Welding fume source: Must sustain a stable emission rate (specified example: 10 mg/s ± 2 mg/s) and collect sample mass on preweighed filters to determine emission rate.
- Preconditioning and test periods: Equipment is precharged with fume for 30 minutes before measurements. For non-cleanable filters a 30-minute measurement determines passing concentration. For cleanable filters additional cycles and averaging are required.
- Measurement inputs: Air volume flow rate of the separation unit, testing time, and source emission rate are all measured and used to calculate incoming concentration and separation efficiency.
- Equipment types covered: Free-standing units, modular systems, units with manually or automatically initiated cleaning systems, and electrostatic precipitators (specific test procedures included).
- Statistical requirements: Two test runs are performed; the average, the 95% one-sided confidence interval and the lower confidence limit are calculated following ISO 2602. If the lower confidence limit is below the required efficiency, design improvements are indicated.
- Scope exclusions: General ventilation systems (see ISO 21904-1) and standalone filter cartridges are excluded.
Practical applications and users
- Manufacturers of fume capture and filtration units use this standard to validate product performance claims and to mark separation efficiency.
- Independent testing laboratories and certification bodies apply the test method to verify compliance.
- Occupational health & safety professionals, procurement teams, and plant engineers use the standard to select effective local exhaust ventilation and recirculating systems that minimize worker exposure to welding fume.
- Regulators and compliance officers rely on standardized test data for safety audits and approvals.
Related standards
- ISO 21904-1:2020 - General requirements for capture and separation equipment
- ISO 15011-1:2009 - Laboratory method for sampling fume and gases (fume emission rate determination)
- ISO 2602 - Statistical interpretation of test results (confidence intervals)
- EN 1093-6 / EN 1093-7 - Related test-method foundations referenced by this document
Keywords: EN ISO 21904-2:2020, welding fume, separation efficiency, capture and separation equipment, testing method, marking, local exhaust ventilation, fume extraction.