EN 17289-2-2020 pdf download.Characterization of bulk materials – Determination of a size-weighted fine fraction and crystalline silica content -Part 2: Calculation method.
The calculation method is applicable only after experiments have shown that the results are accurate and consistently equal or higher than the results from sedimentation, as specified In EN 17289-3, for that particular bulk material.
A specific method for the evaluation of the SWFF for diatomaceous earth bulk materials is given in Annex A. Due to the internal porosity of diatomaceous earth, the general instructions given in this document are adapted In order to take into account the material’s effective density
This document is applicable for crystalline silica containing bulk materials which have been fully investigated and validated for the evaluation of the size-weighted fine fraction and crystalline silica.
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.
EN 481, Workplace atmospheres — Size fraction definitions for measurement of airborne particles EN 1540. Workplace exposure — Terminology
EN 17289-1:2020, Characterization of bulk materials — Determination of a size-weighted fine fraction
and crystalline silica content — Part 1: General information and choice of test methods
ISO 1183-1, Plastics — Methods for determining the density of non-cellular plastics — Part 1: Immersion method, liquid pycnometer method and titration
ISO 133 17-1, Determination of particle size distribution by gravitational liquid sedimentation methods — Part 1: General principles and guidelines
ISO 133 17-2, Determination of particle size distribution by gravitational liquid sedimentation methods — Part 2: Fixed pipette method
ISO 13320, Particle size analysis — Laser diffraction methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1540 and EN 17289-1 apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
4 Symbols and abbreviations
CS crystalline s1ii.i
DE diatomaceous earth
PSD particle size distribution
SWFF size-weighted fine fraction
SWFFCS size-weighted fine fraction of crystalline silica
5 Assumptions
The calculation method is based on the following assumptions:
a) the dynamic form factor is neglected in the determination of the particle size distribution with methods other than methods based on sedimentation;
b) the precondition is that in a mixture the different materials have the same particle size distribution. If this is not the case a separation using the sedimentation method shall be used;
c) the subsample is representative of the bulk material. An appropriate sub-sampling method (see EN 17289-1:2020, 6.1) has been used to ensure the subsample is representative of the bulk material.
6 Determination of SWFF and SWFFCS by calculation
The SWFF of a sample is calculated by first determining its particle size distribution by laser diffraction according to ISO 13320 or gravitational liquid sedimentation by X-ray method according to ISO 13317-1 and ISO 13317—2.
A size weighting is then applied, based on the probability function given in EN 481. i.e. the probability function for particles reaching the alveoli when inhaled, see Formula (1).
where
de is the equivalent diameter as used in the particle size distribution measurement, in q micrometres (lAm);
p0 is the unit density (1 000 kg/rn3), as defined in EN 481;
p is the particle density, in kilograms per cubic metre (kg/rn3).
A standardized method shall be used to determine the particle density, for example, by using a He or liquid pycnometer in accordance with Iso 1183-1.
A more detailed explanation of the derivation of Formula (1)is given in EN 17289-3.
The SWFFCS is calculated by multiplying the SWFF of the sample with the fraction of crystalline silica in the sample, see Formula (3). It is assumed that the particle size distribution of the sample and of the crystalline silica in the sample are the same.
WSWFFCS = WSWFF w / 100 (3)
where
w,FFCS is the size-weighted fine fraction of crystalline silica, in percent (%);
wSWFF is the size-weighted fine fraction, in percent (%);
is the mass fraction of crystalline silica in the bulk sample, in percent (%).
The content of crystalline silica of the sample shall be determined using techniques such as X-ray Powder Diffractometry (XRD) or Infrared Spectroscopy (IR) as specified in EN 17289-1:2020, Clause 5 and Annex C.
For non-spherical particles such as needles and platelets, laser diffraction will tend to overestimate their diameter and additionally, because of their shape, these particles behave as smaller particles in air. Consequently, laser diffraction shall not be used for these kinds of particles because it will result in a SWFF that is too low. Instead gravitational liquid sedimentation is best used in these cases.EN 17289-2-2020 pdf download.
EN 17289-2-2020 pdf download
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