BS/EN 13274-7-2019 pdf download.Respiratory protective devices – Methods of test Part 7: Determination of particle filter penetration.
The test aerosol is fed into the test chamber, where the particle filtering device under test Is mounted In a leaktlght manner on a suitable adaptor. Aerosol Is passed through the device and the aerosol concentration is measured immediately before and after the particle filtering device by the photometer.
Laboratories should give consideration to the following factors.
— Test chamber should be designed to minimize air velocity variations across the surface of the
filter under test.
— Localized high air velocity flets) can result in artificially high filter penetration.
5.2 Nominal values and tolerances
Unless otherwise specified, the values stated In this European Standard are expressed as nominal values. Except for temperature limits, values which are not stated as maxima or minima shall be subject to a tolerance of ±5 %. Unless otherwise specified the ambient temperature for testing shall be in the range between 16°C and 32 °C with a relative humidity of(50 ± 30) % and the temperature limits shall be subject to an accuracy of ii °C.
For each of the required measurements performed in accordance with this standard, a corresponding estimate of the uncertainty of measurement should be evaluated [11.
This estimate of uncertainty should be applied and stated when reporting test results, in order to enable the user of the test report to assess the reliability of the result.
5.3 Penetration test
5.4 Exposure test
Penetration shall be recorded throughout the test at sample intervals not exceeding 5 mm. Continuous recording of penetration is recommended.
For particle filtering devices being tested using paraffin oil, continue the test until the particle filtering device has been exposed to the specified mass of the test aerosol as defined in the appropriate device standard.
For particle filtering devices being tested using sodium chloride, continue the test until the particle filtering device has been exposed to the specified mass of the test aerosol as defined in the appropriate device standard, unless:
a) for single shift use particle filtering devices, the penetration shows continued decline for S mm or 5 sample intervals, whichever is the greater;
b) for re-useable particle filtering devices, the penetration shows continued decline for 5 mm or 5 sample intervals, whichever is the greater, and the maximum penetration Is lower than when tested using paraffin oil test aerosol.
If these conditions are met, the exposure test may be terminated early.
Report the maximum penetration during exposure.
5.5 Storage test
For re-useable particle filtering devices the storage test shall be performed immediately after the completion of the exposure test.
Remove the particle filtering device from the penetration test chamber and store the particle filtering device for a duration of (24 ± 1) h under ambient conditions as specified In Si. ensuring that particle filtering devices are not in contact with each other.
The particle filtering device shall not be removed from the suitable adaptor if this can result in damage to the device.
After storage, Immediately repeat the penetration test in accordance with 53.
6 Sodium chloride test method
6.1 Principle
An aerosol of sodium chloride particles is generated by atomising an aqueous solution of the salt and evaporating the water. The concentration of this aerosol is measured before and after the filter under test by means of flame photometry. Determinations shall be possible in the range < 0.001 % to 100 % filter penetration.
6.2 Test equipment
The apparatus is shown schematically in Figure 1. The test apparatus consists of four modules:
1) cod iiim chloride aerosol generator;
2) flow control;
3) filter test chamber;
4) llame photometer aerosol detector.
The test aerosol produced by the generator Is polydisperse and shall have the following properties:
— the number median of the particle size distribution is between a diameter of 0,06 pm and 0,10 pm with a geometric standard deviation between 2,0 and 3,0;
— the aerosol concentration Is within the range 4 mg/ m3 to 12 mg/rn3
— the variation of the concentration over a period of 5 mm Is not greater than ± 3 % and Is not greater than ±10 % during the exposure test;
— the relative humidity Is 40 % or less at (22 ± 3) °C.
The aerosol mass concentration, particle size distribution and humidity shall be measured within the filter test chamber.
It Is recomniended that an electrical mobility method be used to determine the particle size distribution. Additional information on electrical mobility measurements can be found in ISO 15900.
The sodium chloride solution shall be completely replaced and not replenished in order to maintain the correct solution concentration.
The sodium chloride aerosol Is detected before and after the filtering device under test by flame photometry. Sodium chloride particles In air passing through the flame tube are vaporized giving the characteristic sodium emission at 589 nm. The intensity of this emission is proportional to the concentration of sodium in the air flow.BS/EN 13274-7-2019 pdf download.