SIST EN 15051:2006
(Main)Workplace atmospheres - Measurement of the dustiness of bulk materials - Requirements and reference test methods
Workplace atmospheres - Measurement of the dustiness of bulk materials - Requirements and reference test methods
This document specifies the two reference test apparatuses and reference test methods for the reproducible production of dust from a bulk material under standard conditions, and the measurement of the inhalable, thoracic and respirable fractions of this dust, with reference to the existing CEN standards, where relevant (see Clause 6).
This document specifies the environmental conditions, the sample handling and analysis procedures and the method of calculating and presenting the results. A classification scheme for dustiness is specified, to provide a standardised way to express and communicate the results to users of the bulk materials.
In Annex D, a test method is described that enables dustiness information produced by test methods other than these two reference test methods to be related to that produced using these standard reference test methods.
This document is applicable to powdered, granular or pelletised materials. A standard sample volume is used.
This document is not applicable to test the dust released when solid materials are mechanically reduced (e.g. cut, crushed) or to test handling procedures for the materials.
Arbeitsplatzatmosphäre - Messung des Staubungsverhaltens von Schüttgütern - Anforderungen und Referenzprüfverfahren
Dieses Dokument legt die beiden Referenzprüfeinrichtungen und -verfahren für die reproduzierbare
Staubentwicklung aus einem Schüttgut unter genormten Bedingungen sowie die Messung der einatembaren,
thorakalen und alveolengängigen Fraktionen dieses Staubs unter Verweis auf die vorhandenen Europäischen
Normen fest, sofern diese relevant sind (siehe Abschnitt 6).
Dieses Dokument legt die Umgebungsbedingungen, den Umgang mit den Proben und die Analyseverfahren
sowie die Verfahren zur Berechnung und Darstellung der Ergebnisse fest. Um eine normierte Grundlage für
die Angabe und Weiterleitung der Ergebnisse an die Anwender von Schüttgütern zu schaffen, wird ein
Klassifikationssystem für das Staubungsverhalten festgelegt.
Anhang D beschreibt ein Prüfverfahren, das erlaubt, die Information zum Staubungsverhalten, die nach einem
anderen Verfahren als den beiden Referenzprüfverfahren ermittelt wurde, auf die Information zum
Staubungsverhalten zu beziehen, die nach einem der genormten Referenzprüfverfahren erhalten wurde.
Das vorliegende Dokument gilt für pulverförmige, granulierte oder pelletierte Materialien. Bei der
Prüfungsdurchführung wird ein genormtes Probenvolumen verwendet.
Dieses Dokument gilt nicht für die Prüfung von Staub, der bei der mechanischen Zerkleinerung fester
Materialien (z. B. beim Schneiden, Brechen) freigesetzt wird, oder um Verfahren zur Handhabung von
Schüttgütern zu prüfen.
Atmosphere des lieux de travail - Mesure du pouvoir de resuspension des matériaux pulvérulents en vrac - Exigences et méthodes d'essai de référence
Le présent document spécifie les deux appareillages et méthodes d’essai de référence a utiliser pour produire des poussieres de maniere reproductible, a l’aide de matériaux en vrac, dans des conditions normalisées, en vue de mesurer les fractions inhalable, thoracique et alvéolaire de ces poussieres, en référence aux normes CEN existantes, s’il y a lieu (voir Article 6).
Le présent document spécifie également les conditions ambiantes, les méthodes de manipulation et d'analyse des échantillons ainsi que la méthode de calcul et d'expression des résultats. Une méthode de classification du pouvoir de resuspension est également spécifiée, afin de normaliser le mode d'expression et de communication des résultats aux utilisateurs des matériaux en vrac.
L’Annexe D décrit une méthode d’essai permettant de corréler les données relatives au pouvoir de resuspension obtenues a l'aide de méthodes d’essai autres que ces deux méthodes de référence avec les données obtenues a l'aide des méthodes de la présente norme.
Le présent document s’applique aux matériaux granulaires, en poudre ou sous forme de pastilles. Un volume étalon est utilisé.
Le présent document ne s’applique pas a la détermination de l’empoussierement du a la réduction mécanique (par exemple découpe, concassage) de matériaux solides ni a l’évaluation des méthodes de manipulation des matériaux.
Zrak na delovnem mestu - Meritve prašnosti razsutih materialov - Zahteve in referenčne preskusne metode
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Workplace atmospheres - Measurement of the dustiness of bulk materials - Requirements and reference test methodsAtmosphere des lieux de travail - Mesure du pouvoir de resuspension des matériaux pulvérulents en vrac - Exigences et méthodes d'essai de référenceArbeitsplatzatmosphäre - Messung des Staubungsverhaltens von Schüttgütern - Anforderungen und Referenzprüfverfahren13.040.30Kakovost zraka na delovnem mestuWorkplace atmospheresICS:SIST EN 15051:2006en,fr,deTa slovenski standard je istoveten z:EN 15051:200601-julij-2006SIST EN 15051:2006SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15051April 2006ICS 13.040.30 English VersionWorkplace atmospheres - Measurement of the dustiness of bulkmaterials - Requirements and reference test methodsAtmosphère des lieux de travail - Mesure du pouvoir deresuspension des matériaux pulvérulents en vrac -Exigences et méthodes d'essai de référenceArbeitsplatzatmosphäre - Messung desStaubungsverhaltens von Schüttgütern - Anforderungenund ReferenzprüfverfahrenThis European Standard was approved by CEN on 16 March 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15051:2006: E
EN 15051:2006 (E) 2 Contents Page Foreword.3 Introduction.4 1 Scope.5 2 Normative references.5 3 Terms and definitions.5 4 Principle.6 5 Requirements.7 6 Reference test methods.8 7 Evaluation of dustiness.12 8 Test report.13 Annex A (normative)
Description of reference test apparatus.15 Annex B (normative)
Determination of moisture content.19 Annex C (normative)
Determination of bulk density of the test material.20 Annex D (normative)
Test of equivalence between an alternative (candidate) test method and any of the reference test methods.21 Bibliography.24
EN 15051:2006 (E) 3 Foreword This document (EN 15051:2006) has been prepared by Technical Committee CEN/TC 137 “Assessment of workplace exposure to chemical and biological agents”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2006, and conflicting national standards shall be withdrawn at the latest by October 2006. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EN 15051:2006 (E) 4 Introduction The control of dust emissions during the handling and transportation of materials is an important consideration in the design and operation of many industrial processes. Excessive airborne dust levels in workplaces are undesirable for a number of reasons: a) can cause adverse health effects to the work force;
b) control can involve the use of costly ventilation and filtration systems;
c) can be costly in terms of lost product;
d) can contaminate machinery and products.
It is advantageous, therefore, for occupational hygienists and process engineers to have accurate information about the propensity of materials to produce airborne dust (the ‘dustiness’ of the material) so that risks can be evaluated, controlled and minimised. No single method of dustiness testing is likely to represent and reproduce the various types of processing and handling used in industry. Therefore a number of dustiness testing methods are in use in different industries. Different methods use different test apparatus and measuring principles, and express results in different ways. Methods that do not separate the dust cloud produced into the three health-related size fractions - inhalable, thoracic and respirable dust - can serve the needs of manufacturing industry for process and batch control, but give limited information on the health hazard due to the dustiness of the material. Dustiness is a relative term and the measurement obtained will depend on the test apparatus used, the properties of the dust and various environmental variables. The test and the variables therefore need to be closely specified to ensure reproducibility. Recognising the above it was concluded that there was a need for standardised reference methods to measure the dustiness of bulk materials, based on the biologically relevant aerosol fractions defined in EN 481. This document establishes reference test methods that classify the dustiness, in terms of health-related fractions, of bulk solid materials. The dustiness classification is intended to provide users (e.g. manufacturers, producers, occupational hygienists and workers) with information on the potential for dust emissions when the material is handled or processed in workplaces. It provides the manufacturers of materials with information that can help to improve their products. It allows the users of the materials to assess the effects of pre-treatments, and also to select less dusty products, if available. Although this document does not discuss the analysis of dust released from bulk materials (except in terms of health-related fractions), the test method produces samples with the potential for chemical analysis of the contents. This document also provides reference test methods to which users of alternative test methods on dustiness can compare their own measurements. A standardised test of equivalence is used to test whether the alternative test method is capable of reproducing the dustiness classifications of the reference test methods, for a range of standardised test dusts. If the requirements for equivalence are satisfied the alternative test method can be used to classify the dustiness of bulk materials. This document was developed based on the results of the European project SMT4-CT96-2074 Development of a Method for Dustiness Testing (see [1]). This project investigated the dustiness of 12 materials, with the intention to test as wide a range of materials as possible, i.e. magnitude of dustiness, industrial sectors, chemical composition and particle size distribution.
EN 15051:2006 (E) 5 1 Scope This document specifies the two reference test apparatuses and reference test methods for the reproducible production of dust from a bulk material under standard conditions, and the measurement of the inhalable, thoracic and respirable fractions of this dust, with reference to the existing CEN standards, where relevant (see Clause 6). This document specifies the environmental conditions, the sample handling and analysis procedures and the method of calculating and presenting the results. A classification scheme for dustiness is specified, to provide a standardised way to express and communicate the results to users of the bulk materials. In Annex D, a test method is described that enables dustiness information produced by test methods other than these two reference test methods to be related to that produced using these standard reference test methods. This document is applicable to powdered, granular or pelletised materials. A standard sample volume is used.
This document is not applicable to test the dust released when solid materials are mechanically reduced (e.g. cut, crushed) or to test handling procedures for the materials. 2 Normative references The following referenced documents are indispensable for the application 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 1232, Workplace atmospheres - Pumps for personal sampling of chemical agents - Requirements and test methods EN 13205, Workplace atmospheres – Assessment of performance of instruments for measurement of airborne particle concentrations ISO 15767, Workplace atmospheres – Controlling and characterizing errors in weighing collected aerosols 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 airborne dust finely divided matter in solid form, dispersed in air 3.2 health-related fractions inhalable, thoracic and respirable fractions of airborne dust NOTE For definitions of the inhalable, thoracic and respirable fractions, see EN 481. 3.3 collected sample airborne particles collected on the sampling media (e.g. filter, foam or impaction plate) for subsequent analysis NOTE Sample deposits in other parts of the sampler such as inner walls are only included in the collected sample where the method description includes specific instructions for the recovery of such deposits.
EN 15051:2006 (E) 6 3.4 dustiness propensity of materials to produce airborne dust during handling NOTE For the purposes of this document, dustiness is derived from the amount of dust emitted during a standard test procedure. 3.5 inhalable dustiness
dustiness classification of the inhalable fraction NOTE Classification assigned according to the scheme described in Clause 7. 3.6 thoracic dustiness dustiness classification of the thoracic fraction NOTE Classification assigned according to the scheme described in Clause 7. 3.7 respirable dustiness dustiness classification of the respirable fraction NOTE Classification assigned according to the scheme described in Clause 7. 3.8 inhalable dustiness mass fraction wI,A , wI,B ratio of the inhalable dust produced by the dustiness test procedure, in milligrams, to the test mass of material used for the test, in kilograms NOTE For reference test method A the value of the test mass equals the initial mass, and for reference test method B the value of the test mass equals the mass collected in the collector tank. 3.9 thoracic dustiness mass fraction wT,A ratio of the thoracic dust produced by the dustiness test procedure, in milligrams, to the initial mass of material used for the test, in kilograms 3.10 respirable dustiness mass fraction wR,A , wR,B ratio of the respirable dust produced by the dustiness test procedure, in milligrams, to the test mass of material used for the test, in kilograms NOTE For reference test method A the value of the test mass equals the initial mass, and for reference test method B the value of the test mass equals the mass collected in the collector tank. 4 Principle A dustiness tester consists of the following elements: dust generation section; dust transfer section; sampling section;
EN 15051:2006 (E) 7 size fractionator(s); dust collection section. A standard volume of bulk material, with known moisture content, is weighed and then placed in the dust generation section, where it is treated under standard conditions for a set period of time. The airborne dust released is drawn from the dust generation section, through the dust transfer section, into the sampling section. Here, the size fractionator(s) classifies the airborne dust according to aerodynamic particle size. The dust collection section deposits the dust fractions onto suitable media for gravimetric analysis. The results are used to calculate the inhalable, thoracic and respirable dustiness mass fractions of the released dust, in relation to the initial mass of material used. These data are used to classify the dustiness of the material. 5 Requirements 5.1 Condition of the material The material should be delivered in air-tight containers and should be tested in the state in which it was received (moisture content, particle size distribution, etc.). 5.2 Sample and environmental control Materials that have a large specific area are sensitive to ambient conditions such as relative humidity, temperature, electrostatic effects and to their own moisture content, compaction, agglomeration etc. Therefore for accurate results a system controlling the test atmosphere within a narrow range of temperature and humidity should be used. In all cases the environmental conditions shall be documented.
Test conditions: relative humidity (RH): (50 ± 10) %; temperature: (21 ± 3) °C; The test apparatus should be electrically grounded. NOTE In many cases, a separate determination of the particle size can be valuable. 5.3 Moisture content The moisture content of the bulk material shall be determined and documented according to the procedure given in Annex B. 5.4 Bulk density The bulk density of the test material shall be determined and documented according to the procedure given in Annex C. 5.5 Test procedure The dustiness shall be tested according to one of the reference test methods described in Clause 6 and Annex A. The choice of reference test method shall be justified in the test report, see Clause 6. Providing the requirements for equivalence are satisfied, the dustiness may be tested using an alternative test method (see Annex D).
EN 15051:2006 (E) 8 5.6 Replication Replicate tests shall be carried out according to the specific reference test methods A or B, see Clause 6. 5.7 Reporting The test results shall be reported as specified in Clause 7. 6 Reference test methods 6.1 General Two reference test methods are given: Method A produces dust by a multiple continuous dropping process of the bulk material, whereas Method B produces dust by dropping the bulk material once under gravity. Both reference test methods are intended to simulate general handling processes, which involve dropping processes of powdery material at some stage. The two reference test methods differ however with respect to the intensity and the duration of treatment of the bulk material. See 6.2.1 and 6.3.1. This is intentional, as in practice the dust-creating processes in the workplace will also have different characteristics. In some few cases the two reference test methods will give different results. Examples of this are bulk materials that can agglomerate and bulk materials that comprise brittle powder structures that can break after prolonged handling, see for example the data for sulphur in Tables D.1 and D.2. Because of these effects, users of this document should choose the reference test method for the measurement of the dustiness most appropriate to their material and handling process, and shall state this chosen reference test method in their test report. 6.2 Method A: Rotating drum method 6.2.1 General The rotating drum method involves the continuous multiple dropping of a sample of the material in a slow horizontal winnowing current of air. The dust released from dropping material is conducted by the airflow to a sampling section where it is separated aerodynamically into the three health-related fractions by a process of horizontal elutriation and inertial impaction in two stages of porous metal foam. The standard reference test apparatus is described in A.1. 6.2.2 Preparation of test sample Test samples should be extracted from the bulk material using a method, which would result in representative sampling (see e.g. BS 3406-1 or DIN 51701-3). A minimum of six samples is prepared. Sample bottles able to be sealed should be used to minimise contamination of the atmosphere. Test samples with a volume of about 35 cm3 should be extracted and weighed to the nearest± 0,1 g. 6.2.3 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 and allowed to dry. For material that sticks 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). Assemble the inlet and outlet stages to appropriate ends of the drum. Switch on the pump and set the flow rate to 38 l min-1. Turn off the pump.
The test apparatus shall only be cleaned as described in this clause before the first test run. Between the test runs, after the inlet and outlet stages have been removed, the apparatus shall be cleaned by pouring out the remaining material into a waste receptacle. Then, with the drum vertical, the side of the drum is tapped with a soft hammer to remove the loose material from the internal surfaces of the drum.
EN 15051:2006 (E) 9 6.2.4 Test procedure Remove the inlet and outlet stages at both ends of the drum. Spread the test sample evenly along the bottom of the drum. Reassemble both the inlet stage with a fresh protective filter, and the outlet stage with fresh foams and filters. The timing circuit is then switched on and the test programme allowed to proceed. At the end of the test, carefully remove the foams and the filter from the outlet end of the drum and place them in an environmentally controlled balance room, taking care not to disturb the collected sample. For each material carry out at least three runs (all with a cleaned drum and fresh sets of foams and filter), and increase the number of runs if the relative standard deviation of the measured dustiness mass fractions are high.
6.2.5 Weighing the foams and filters The mass of the collected sample is determined by weighing the foams and filters before and after the test. All weighing shall be done in accordance with ISO 15767. After the test, the foams and filter are reweighed in the same sequence. As the test materials and filters are sensitive to moisture and electrostatic conditions in the atmosphere, it is essential that a protocol be followed as to when the mass indicated by the balance should be recorded. The reading of the balance should be taken at a set period (e.g. 30 s) after the specimen is placed on the balance pan and the balance door closed, or when the reading of the balance is stabilised. In order to minimise the risk of disturbance and loss of material foams and filters should be handled or lifted only at their edges and kept to a minimum. Gloves should be worn or tweezers used to lift or handle the foams, and only tweezers used when handling the filters. The masses m of dust collected in the size selecting stages n are calculated by equation (1): )()(Ci,Cf,Si,Sf,nnnnnmmmmm−−−=∆ (1) where ∆mn
is the mass of dust collected by the n th stage, in milligrams; mf,Sn is the final mass of the n th test stage substrate, in milligrams; mi,Sn is the initial mass of the n th test stage substrate, in milligrams; mf,Cn is the final mass of the n th control stage substrate, in milligrams; mi,Cn is the initial mass of the n th control stage substrate, in milligrams. The n th test stage substrate corresponds to either the 800 pores per meter (20 ppi) foam, the 3 200 pores per meter (80 ppi) foam or the backing filter in the foam/filter assembly. The use of the control stage substrates enables the correction of any mass change in the foams and filters due to changing environmental conditions between the two weighings. 6.2.6 Determination of the inhalable, thoracic and respirable dustiness mass fractions The dustiness mass fraction of each health-related fraction, given in milligrams per kilogram (mg kg-1), is calculated by dividing the mass collected from each health-related fraction, in milligrams, by the mass, in kilograms, of the material placed in the test apparatus. The dustiness mass fractions shall be calculated using equations (2) to (4):
EN 15051:2006 (E) 10 sf8020AI,mmmmw∆∆∆++= (2) sf80AT,mmmw∆∆+= (3) sfAR,mmw∆= (4) where wI,A
is the inhalable dustiness mass fraction, in milligrams per kilogram; wT,A
is the thoracic dustiness mass fraction, in milligrams per kilogram; wR,A
is the respirable dustiness mass fraction, in milligrams per kilogram; ms
is the mass of the test sample; ∆m20 is the mass collected by the 800 pores per meter (20 ppi) foam; ∆m80 is the mass collected by the 3 200 pores per meter (80 ppi) foam; ∆mf
is the mass collected by the backing filter. For each dustiness mass fraction, calculate the average and the standard deviation. The average is used for the classification in Clause 7. 6.3 Method B: Continuous drop method 6.3.1 General The continuous drop method involves the continuous single dropping of material in a slow vertical air current. The dust released from dropping material is conducted by the airflow to a sampling section where it is separated aerodynamically into the inhalable and respirable fractions. The standard reference test apparatus is described in A.2. 6.3.2 Preparation of test sample The amount of sample material required is obtained from the drop mass flow (6 g min-1 to 10 g min-1), the measuring duration (standard 10 min), the intended number of tests (i.e. 5) and allowance for adequate filling of the metering device. Normally at least 500 g of sample material is required. Test samples should be extracted from the bulk material using a method, which will result in representative sampling (see e.g. DIN 51701-3 or BS 3406-1). 6.3.3 Preparation of test apparatus Before carrying out the measurements on the sample, the backflow pipe, the collector tank, the sampling heads and also the main flow pump protective filter shall be carefully cleaned. Before performing the actual test runs the drop mass flow shall be adjusted to the desired rate. This preliminary activity (see A.2) is considered as a conditioning step for the test apparatus.
EN 15051:2006 (E) 11 The test apparatus shall neither be cleaned (as described above) between the single test runs nor between the conditioning run and the first test run. 6.3.4 Test procedure The sample material is to be loaded to the sample tank in the as-delivered state without dust loss, if necessary with the aid of a spoon or spatula, so that the sample tank is adequately filled even after the planned individual tests have been performed. The speed of the metering device is to be set by weighing (repeatedly if necessary) the drop mass so that a drop mass flow from 6 g min-1 to 10 g min-1 is achieved. The sampling heads are to be fitted with filters weighed by means of an analytical balance. The cleaned collector tank is weighed and secured in place. NOTE Filters can be plane filters, like those used in workplace air sampling, or filter thimbles with higher storage capacity (see A.2.2). Begin the measurement by using the following switch-on sequence:
main flow pump; respirable dust pump; inhalable dust pump; metering device; The measurement starts by turning on the metering device. At the end of the measurement, normally after 10 min operation time, the units are switched off simultaneously. The filled collector tank is removed, weighed, emptied and cleaned. The loaded respirable dust and inhalable dust filters are removed from the sampling heads and weighed using an analytical balance. 6.3.5 Weighing the filters Weighing of the filters or filter thimbles shall be done in accordance with ISO 15767. 6.3.6 Determination of the inhalable and respirable dustiness mass fractions The inhalable and respirable dustiness mass fractions wI,B and wR,B, in milligrams per kilogram (mg kg-1), are calculated according to the equations (5) and (6) for each single test. The average values and relative standard deviations from five individual measurements of both, the inhalable and respirable dustiness mass fractions shall be calculated. Both values shall be stated in the test report. ItotcIBI,QQmmw⋅=∆ (5) RtotcRBR,QQmmw⋅=∆ (6) mIRtotQQQQ++= (7) where ∆mI
is the mass of the dust collected by the sampling head for inhalable dust, in milligrams;
EN 15051:2006 (E) 12 ∆mR
is the mass of the dust collected by the sampling head for respirable dust, in milligrams; mc
is the drop mass in the collector tank, in kilograms; Qtot
is the total flow rate, in litres per minute; QI
is the flow rate of the sampling head for inhalable dust, in litres per minute; QR
is the flow rate of the sampling head for respirable dust, in litres per minute; Qm
is the main pump flow rate, in litres per minute; NOTE In order to be exactly correct, equations (5) and (6) presumes iso-kinetic sampling of the respirable and inhalable fractions and homogeneous distribution of particles across the backflow pipe. However, here the equations are used to define dustiness mass fraction values approximately independent of the sampling flow rate. For each dustiness mass fraction, the average value is used for the classification in Clause 7. 7 Evaluation of dustiness The measured values of inhalable, thoracic or respirable dustiness mass fractions of different materials can be used for several purposes: a) to classify bulk materials according to their propensity to emit dust and thus aid occupational hygienists and process engineers to evaluate and control the health risk of airborne dust; b) to optimise some technical properties of materials. The dustiness of the material shall be classified into one of four categories, i.e. very low, low, moderate or high, on the basis of the dustiness mass fractions in each health-related fraction. The classification shall be according to the appropriate scheme for the reference test method used. The classification schemes for the two reference test methods A and B are given in Tables 1 and 2, respectively. NOTE 1 The classification tables apply to the reference test methods and apparatuses given in Clause 6 and Annex A. The test of equivalence described in Annex D is used to devise a different classification table for any alternative (i.e. non-reference) test method.
NOTE 2 The classification was based upon data gathered from using the reference test methods A and B to measure the dustiness of 12 different materials in the EU funded project SMT4-CT96-2074 (see [1]). NOTE 3 The two reference test methods gives different values for the amount of dust released into the air because generation techniques and amount of energy supplied are different. Numerical dustiness values can only be compared within the same reference test method, but not between reference test methods. The two reference test methods give similar rank orders of tested bulk materials, but for occasional examples the differences can be large. See Tables D.1 and D.2.
EN 15051:2006 (E) 13 Table 1 — Dustiness classification for Method A: Rotating drum Category of dustiness Inhalable dustiness mass fraction, wI,A mg kg-1 Thoracic dustiness mass fraction, wT,A mg kg-1 Respirable dustiness mass fraction, wR,A mg kg-1 Very low < 200 < 40 <10 Low 200 to 1 000 40 to 200 10 to 50 Moderate > 1 000 to 5 000 > 200 to 1 000 > 50 to 250 High > 5 000 > 1 000 > 250 NOTE 4 In the EU funded project SMT4-CT96-2074 (see [1]), 12 different materials were tested for dustiness with method A. The range of measured inhalable dustiness mass fractions was from 170 mg kg-1 to 9 000 mg kg-1, the range of measured thoracic dustiness mass fractions was from 10 mg kg-1 to 3 000 mg kg-1 and the range of measured respirable dustiness mass fractions was from 3 mg kg-1 to 400 mg kg-1. Table 2 — Dustiness classification for Method B: Continuous drop
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