BS EN ISO 21904‑2:2020 pdf download.Health and safety in welding and allied processes – Equipment for capture and separation of welding fume.
2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 2602:1980, Statistical interpretation of test results — Estimation of the mean — Confidence interval ISO 15011‑1:2009, Health and safety in welding and allied processes — Laboratory method for sampling fume and gases — Part 1: Determination of fume emission rate during arc welding and collection of fume for analysis ISO 21904‑1:2020, Health and safety in welding and allied processes — Equipment for capture and separation of welding fume — Part 1: General requirements
3? Terms? and? definitions
For the purposes of this document, the terms and definitions given in ISO 21904‑1 and the
following apply.
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4 Principle The method is based on the methods specified in EN 1093‑6 [10] and EN 1093‑7 [11] . Under test, the welding fume separation equipment is charged by welding fume generated by a welding process. The welding fume concentrations are measured in the incoming and exhausted air of the separation unit. The welding fume separation equipment under test is operated under defined conditions, according to its intended use. The emission rate of the welding fume source is measured separately. Therefore, the welding fume generated by the source is sampled on preweighed filters over a period of time. The air volume flow rate of the welding fume separation equipment and the testing time shall be measured during the separation efficiency test. Emission rate, testing time and air volume flow rate are used subsequently to calculate the concentration of welding fume in the incoming air. Welding parameters should be the same when emission rate and separation efficiency test are performed.
Before separation efficiency measurements are made, all welding fume separation equipment are charged for a period of 30 min using the welding fume source. For equipment with filters that are not intended to be cleaned, the concentration of welding fume passing through the separation equipment is measured subsequently for a period of 30 min and the measured concentration is used, together with the welding fume concentration calculated from the welding fume emission rate, to determine the separation efficiency. For equipment with cleanable filters, an additional separation efficiency measurement is performed after a further welding period without measurement and filter cleaning. The average of the two separation efficiencies is calculated. Two tests are performed and the average, the 95 % one-sided confidence interval and the lower confidence limit value of the separation efficiency are calculated according to ISO 2602. If the resulting lower confidence limit value is less than the required separation efficiency, consideration shall be given to improve the filter unit design.BS EN ISO 21904‑2 pdf download.