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ISO 21904-2 pdf free download

ISO 21904-2-2020 pdf free download.Health and safety in welding and allied processes一Equipment for capture and separation of welding fume一 Part 2: Requirements for testing and marking of separation efficiency.
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 offume 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 2 1904-1 and the following apply.
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3.1 free-standing unit
separation equipment with an integrated fan
3.2 modular system
separation equipment consisting of a scaleable filter system with the same filter elements and conditions normally connected to a single fan
3.3 welding fume source
source generating welding fume by welding process that charges separation equipment to perform separation efficiency tests
3.4 emission rate
mass of the particles emitted by the welding fume source per time
Note 1 to entry: The emission rate is expressed in milligrams per second.
4 Principle
The method Is based on the methods specified In EN 1093-6Di and EN 1093.7I1tl. 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 mm 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 mm 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 2602.11 the resulting lower confidence limit value is less than the required separation efficiency, consideration shall be given to improve the filter unit design.
5 Apparatus
5.1 WeldIng fume source, capable of maintaining an emission rate of 10 mg/s ± 2 mg/s throughout the test period.
The welding fume source shall he fitted with an extraction hood that retains all the welding fume emitted and shall he designed in such a way that it can be connected to the inlet duct of the test cabin, as described in Figure 1. or directly to welding fume separation equipment with a ducted outlet, as described in Figure 2. It shall be possible to determine the welding fume emission rate in situ without disturbing the welding set-up in any way. An example of a suitable welding fume source and parameters required to achieve the required welding fume emission rate are described in Aiuiexfi.ISO 21904-2 pdf download.

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