BS/EN 17199-4-2019 pdf download.Workplace exposure – Measurement of dustiness of bulk materials that contain or release respirable NOAA or other respirable particles Part 4: Small rotating drum method.
implemented to prevent exposure of the operator during the tests, but also during disassembly and cleaning sequences between individual test runs.
Occupational risks should be assessed according to national regulations.
7.3 Conditioning of the test material
Because powders and the number-based dustiness index can be sensitive to the relative humidity during storage, the test powder samples shall be conditioned at least 12 h (overnight) before testing. In standard test conditions, the samples shall be stored at room temperature with air conditioned at (50 ± 5) % RH.
NOTE The storage at controlled % RH test conditions can be done in different ways. One possibility is to use the same humidifier, which is used to condition the air for dustiness testing, and connect this to a chamber suitable In size. Alternatively, a humidity-controlled laboratory room or a separate humidity-controlled chamber can be used.
7.4 Conditioning of the test equipment
For testing under standard conditions, the average conditions for temperature and relative humidity inside the drum shall be (21 ± 3) °C and (50 ± 5 % RH), respectively, and shall be stable throughout the entire test period. These conditions are provided by the air from the humidifier feeding the test atmosphere into the drum (see Figure 1).
The test apparatus shall be electrically grounded to prevent charge accumulation.
8 Preparation
8.1 Weighing of filters
At least four filters (depending on which filter type has lowest limit of quantification in the specific laboratory) shall be prepared for each powder sample for collection of respirable dust with the cyclone for the respirable dust fraction. The four filters include one backup, if a fourth sample will be needed to reduce uncertainty or errors. For each weighing round (e.g., one-week-sets of tests) three blank filters shall be included to take into account filter variations and handling.
Before weighing (before and after use in test), the filters shall be conditioned, at least overnight, in a climate-controlled weighing room and weighed.
8.2 Test sample
One 2 g sample for conditioning testing and four at least 6 g samples for quantitative dustiness testing are incubated for 24 Ii at the intended test conditions (i.e. (21 ± 5) °C; (50 ± 5) % RH).
For the determination of moisture content and bulk density (see 8.3 and 8.4) sufficient sample amounts are incubated at the desired test conditions.
8.4 Bulk density of the test material
The bulk density of the test material shall be determined and documented according to the procedure given in EN 17199-1.
8.5 Preparation of test apparatus
Prior to the tests being carried out, the rotating drum is cleaned thoroughly using a suitable vacuum cleaner, wiped with a damp cloth (e.g. alcohol-wetted cloths) and allowed to dry. For test materials that stick to the internal surfaces, it can also be necessary to wash the surfaces with a solution of a detergent in water followed by thorough washing with water, or to clean with a suitable solvent (e.g. propanol).
The tube connecting the drum (item number I in Figure 1)and the sampling line (item number 4 in Figure 1) is attached to the outlet stage of the drum using a rotating coupling device. The dust transmission line is connected to the sampling line using a tight fitting stainless connecter (item number 3 in Figure 1).
The volume flow rates of air provided by the humidifiers and all the pumps, devices and real-time instruments are checked using air volume flow meters and adjusted, if necessary, to balance the total collection air volume flow to the total volume flow of 11 1/mm into the drum as depicted in Figure 1.
The instruments are connected to the sampling line using stainless metal or alloy tubes or conductive tubing as shown in Figure 1. Bends in tubing shall be avoided to the extent possible.
8.6 Aerosol instruments and aerosol samplers
Instruments shall be switched on in due time to allow equilibration of the real-time monitors. For example, if the ELPI* is used, it shall be switched on several hours before any measurements take place, preferably the day before. This allows the electrometers to fully stabilize.
Sintered collection plates shall be prepared as recommended by the manufacturer of the ELPP’. In case Al-plates are used, greasing shall be done using one to two drops of vacuum pump oil per plate. When a new powder sample is being tested, the plates and insulators need to be cleaned in an ultrasonic bath with alcohol.
The ELPl leak test and zeroing procedure shall take place prior to any measurements. The zeroing” procedure shall be performed with the drum empty, the instrument connected to the drum and the other instruments and devices operating. The external HEPA-filter to the air inlet may be used and the charger shall be on during the zeroIng procedure.
At the start of a test day, a zero check of the CPC shall be carried out by applying HEPA-fllters to the sampling line.
All devices and instruments flow rates shall be checked using in-line air flowmeters before and after the test, and the values shall be recorded.BS/EN 17199-4-2019 pdf download.
BS/EN 17199-4-2019 pdf download
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