ISO 16900-4-2011 pdf free download

ISO 16900-4-2011 pdf free download.Respiratory protective devices Methods of test and test equipment
Part 4:Determination of gas filter capacity and migration, desorption and carbon monoxide dynamic testing
Appareils de protection respiratoire — Méthodes d’essai et équipement d’essai — Partie 4: Determination de Ia capacité dun filtre a gaz et essais de migration, de désorption et dynamique au monoxyde de carbone.
The test gas and water vapour concentrations, as well as the differential pressure in the test chamber, shall be monitored and recorded continuously during the test. The effect of humidity of the challenge atmosphere by exhaled air returning to the test chamber shall be taken into account by adequate placing of the humidity measuring point.
The effect of differential pressure and of the dilution of the challenge atmosphere by exhaled air returning to the test chamber shall be taken into account and the concentration of the test gas and moisture shall be adjusted accordingly.
Care shall be taken that the influence of the exhaled air to the challenge gas concentration at the point of the air inlet to the test specimen is minimized. The dry bulb temperature and the concentration of the challenge gas shall be measured 10 mm to 20 mm in front of the air inlet of the test specimen.
The dry bulb temperature of the inhaled air shall be measured using a fast response thermocouple (e.g. N iCr-Ni 0.2 mm diameter).
8.3.3.2 BidirectIonal method
In the bidirectional method, the test gas flows through the filter during the inhalation and the exhalation phase. This method requires a test set as shown in Figure 2 where the humidifier (key 3) and the gas cooler (key 4) shall be used.
8.3.3.3 Unidirectional method
In the unidirectional method, the test gas flows through the filter only during the inhalation phase. This method requires a test set as shown in Figure 2 where the humidifier (key 3) and the gas cooler (key 4) shall not be used.
8.4 Gas filter validation test at specified flow rates
Test gases used shall be as specified in the performance standards.
The test gas shall be passed through the filter in continuous flow mode at the flow rate(s), humidity and temperature specified in the performance standard.
The concentration of the test gas and specified reaction products, if applicable, in the effluent air shall be recorded during the test until breakthrough occurs, or until the minimum specified time has been reached, (including compensation for variations from the nominal value of influent concentration), whichever is sooner.
An alternative method for conducting the validation test at specified flow rates greater than 110 1/mm for testing non-catalytic filter types OV, AC, BC and 0G. or their combination(s), is given in Annex B.ISO 16900-4-2011 pdf free download.