SIST EN 1822-2:2010
(Main)High efficiency air filters (EPA, HEPA and ULPA) - Part 2: Aerosol production, measuring equipment, particle counting statistics
High efficiency air filters (EPA, HEPA and ULPA) - Part 2: Aerosol production, measuring equipment, particle counting statistics
This European Standard applies to efficient particulate air filters (EPA) high efficiency particulate air filters (HEPA) and ultra low penetration air filters (ULPA) used in the field of ventilation and air conditioning and for technical processes, e.g. for clean room
technology or applications in the nuclear and pharmaceutical industry. It establishes a procedure for the determination of the efficiency on the basis of a particle counting method using a liquid (or alternatively a solid) test aerosol, and allows a standardized
classification of these filters in terms of their efficiency, both local and overall efficiency. This European Standard describes the measuring instruments and aerosol generators used in the course of this testing. With regard to particle counting it specifies the statistical basis for the evaluation of counts with only small numbers of counted events.
Schwebstofffilter (EPA, HEPA und ULPA) - Teil 2: Aerosolerzeugung, Meßgeräte, Partikelzählstatistik
Diese Europäische Norm gilt für Hochleistungs-Partikelfilter und Hochleistungs-Schwebstofffilter (EPA, HEPA
und ULPA) im Bereich der Raum- und Prozesslufttechnik, z. B. Anwendungen in der Reinraumtechnik oder in
der pharmazeutischen Industrie.
Sie legt ein Verfahren zur Prüfung des Abscheidegrades auf Basis von Partikelzählverfahren unter
Verwendung eines flüssigen (oder alternativ eines festen) Prüfaerosols fest und ermöglicht eine einheitliche
Klassifizierung der Schwebstofffilter nach dem Abscheidegrad, sowohl nach dem integralen als auch nach
dem lokalen Abscheidegrad.
Diese Europäische Norm beschreibt die im Rahmen dieser Prüfung verwendeten Messgeräte und
Aerosolgeneratoren. Darüber hinaus beschreibt sie für Partikelzählungen die statistischen Grundlagen zur
Auswertung von Zählergebnissen bei nur geringer Anzahl von Zählereignissen.
Filtres à air à haute efficacité (EPA, HEPA et ULPA) - Partie 2: Production d'aérosol, équipement de mesure et statistiques de comptage de particules
La présente Norme européenne s'applique aux filtres à air à haute efficacité (EPA), aux filtres à très haute efficacité et aux filtres à air à très faible pénétration (ULPA) utilisés dans le domaine de la ventilation et de l'air conditionné, ainsi que dans des procédés techniques, par exemple pour des application de technique en salle blanche ou dans l'industrie pharmaceutique.
Elle définit une méthode de détermination de l'efficacité, à partir d'une méthode du comptage de particules à l'aide d'un aérosol d'essai liquide (ou à particules solides) et permet une classification normalisée de ces filtres en fonction de leur efficacité, locale et globale.
La présente Norme européenne décrit les instruments de mesure et les générateurs d'aérosol utilisés au cours de ces essais. Pour ce qui est du comptage de particules, elle spécifie les bases statistiques de l'évaluation des comptages effectués sur un nombre limité d'événements.
Visoko učinkoviti zračni filtri (EPA, HEPA in ULPA) - 2. del: Proizvodnja aerosola, merilna oprema, statistika štetja delcev
Ta evropski standard velja za učinkovite zračne filtre drobnih delcev (EPA), visoko učinkovite zračne filtre drobnih delcev (HEPA) in zračne filtre z ultra nizko penetracijo (ULPA), ki se uporabljajo na področju prezračevanja in klimatizacije ter za tehnične postopke, npr. za naprave v tehnologiji čistega prostora ali farmacevtski industriji. Vzpostavlja postopek za določitev učinkovitosti na osnovi metode štetja delcev z uporabo tekočega testnega aerosola (ali v trdnem stanju kot druga možnost) ter omogoča standardizirano klasifikacijo teh filtrov glede na njihovo učinkovitost, tako lokalno kot celovito učinkovitosti. Ta evropski standard opisuje merilne instrumente in aerosolne razpršilce, ki se uporabljajo pri tem preskušanju. Kar se tiče štetja delcev, določa statistično osnovo za vrednotenje štetja pri le majhnem številu štetih dogodkov.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Schwebstofffilter (EPA, HEPA und ULPA) - Teil 2: Aerosolerzeugung, Meßgeräte, PartikelzählstatistikFiltres à air à haute efficacité (EPA, HEPA et ULPA) - Partie 2: Production d'aérosol, équipement de mesure et statistiques de comptage de particulesHigh efficiency air filters (EPA, HEPA and ULPA) - Part 2: Aerosol production, measuring equipment, particle counting statistics23.120QDSUDYHVentilators. Fans. Air-conditionersICS:Ta slovenski standard je istoveten z:EN 1822-2:2009SIST EN 1822-2:2010en,fr01-januar-2010SIST EN 1822-2:2010SLOVENSKI
STANDARDSIST EN 1822-2:20001DGRPHãþD
SIST EN 1822-2:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 1822-2
November 2009 ICS 13.040.40 Supersedes EN 1822-2:1998English Version
High efficiency air filters (EPA, HEPA and ULPA) - Part 2: Aerosol production, measuring equipment, particle counting statistics
Filtres à air à haute efficacité (EPA, HEPA et ULPA) - Partie 2: Production d'aérosol, équipement de mesure et statistiques de comptage de particules
Schwebstofffilter (EPA, HEPA und ULPA) - Teil 2: Aerosolerzeugung, Meßgeräte, Partikelzählstatistik This European Standard was approved by CEN on 17 October 2009.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, 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 STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1822-2:2009: ESIST EN 1822-2:2010
EN 1822-2:2009 (E) 2 Contents Page Foreword .3Introduction .41Scope .52Normative references .53Terms and definitions .54Aerosol production .54.1General .54.2Aerosol substances .54.3Producing monodisperse aerosols.74.3.1Condensation methods .74.3.2Particle size classification . 114.4Generating polydisperse aerosols . 114.5Neutralisation of aerosols . 114.6Minimum performance parameters for aerosol generators . 124.7Sources of error . 124.8Maintenance and inspection . 125Measuring devices . 125.1Optical particle counters . 125.1.1Operation . 125.1.2Minimum performance parameters . 135.1.3Sources of error and limit errors . 145.1.4Maintenance and inspection . 145.1.5Calibration . 145.2Condensation nucleus counter . 145.2.1Operation . 145.2.2Minimum performance parameters . 165.2.3Sources of error and limit errors . 165.2.4Maintenance and inspection . 175.2.5Calibration . 175.3Differential mobility analyser . 175.3.1Operation . 175.3.2Minimum performance parameters . 185.3.3Sources of error and limit errors . 185.3.4Maintenance and inspection . 195.3.5Calibration . 195.4Particle size analysis system on the basis of differential mobility analysis . 195.4.1Operation . 195.4.2Minimum performance parameters . 195.4.3Sources of errors and error limits . 195.4.4Maintenance and inspection . 195.4.5Calibration . 195.5Dilution systems . 205.5.1Operation . 205.5.2Minimum performance parameters . 205.5.3Sources of error and limit errors . 205.5.4Maintenance and inspection . 205.6Differential pressure measuring equipment . 205.7Absolute pressure measuring equipment . 215.8Thermometers . 215.9Hygrometer . 216Maintenance and inspection intervals . 217Particle counting statistics . 23Bibliography . 25 SIST EN 1822-2:2010
EN 1822-2:2009 (E) 3 Foreword This document (EN 1822-2:2009) has been prepared by Technical Committee CEN/TC 195 “Air filters for general air cleaning”, the secretariat of which is held by UNI. 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 May 2010, and conflicting national standards shall be withdrawn at the latest by May 2010. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 1822-2:1998. It is dealing with the performance testing of efficient particulate air filters (EPA), high efficiency particulate air filters (HEPA) and ultra low penetration air filters (ULPA) at the manufacturers site. EN 1822, High efficiency air filters (EPA, HEPA and ULPA), consists of the following parts: Part 1: Classification, performance testing, marking Part 2: Aerosol production, measuring equipment, particle counting statistics Part 3: Testing flat sheet filter media Part 4: Determining leakage of filter elements (scan method) Part 5 : Determining the efficiency of filter elements This European Standard is based on particle counting methods which actually cover most needs of different applications. The difference between this European Standard and its previous edition lies in the addition of: an alternative test method for using a solid, instead of a liquid, test aerosol; a method for testing and classification of filters made out of membrane type filter media; a method for testing and classification filters made out of synthetic fibre media; and an alternative method for leak testing of group H filters with other than panel shape. Beside that, various editorial corrections have been implemented.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, 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 the United Kingdom.
SIST EN 1822-2:2010
EN 1822-2:2009 (E) 4 Introduction As decided by CEN/TC 195, this European Standard is based on particle counting methods which actually cover most needs of different applications. The difference between this European Standard and previous national standards lies in the technique used for the determination of the integral efficiency. Instead of mass relationships, this technique is based on particle counting at the most penetrating particle size (MPPS), which is for micro-glass filter mediums usually in the range of 0,12 µm to 0,25 µm. For Membrane filter media, separate rules apply; see EN 1822-5:2009, Annex A. This method also allows testing ultra low penetration air filters, which was not possible with the previous test methods because of their inadequate sensitivity. SIST EN 1822-2:2010
EN 1822-2:2009 (E) 5 1 Scope This European Standard applies to efficient particulate air filters (EPA), high efficiency particulate air filters (HEPA) and ultra low penetration air filters (ULPA) used in the field of ventilation and air conditioning and for technical processes, e.g. for applications in clean room technology or pharmaceutical industry. It establishes a procedure for the determination of the efficiency on the basis of a particle counting method using a liquid (or alternatively a solid) test aerosol, and allows a standardized classification of these filters in terms of their efficiency, both local and integral efficiency. This European Standard describes the measuring instruments and aerosol generators used in the course of this testing. With regard to particle counting it specifies the statistical basis for the evaluation of counts with only small numbers of counted events. 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 1822-1:2009, High efficiency air filters (EPA, HEPA and ULPA) — Part 1: Classification, performance testing, marking EN 1822-3, High efficiency air filters (EPA, HEPA and ULPA) — Part 3: Testing flat sheet filter media EN 14799:2007, Air filters for general air cleaning — Terminology 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 14799:2007 apply. 4 Aerosol production 4.1 General When testing a filter a test aerosol with liquid particles shall be used as reference test method and as defined in EN 1822-1. Alternatively, a solid PSL aerosol can be used for local efficiency (leak) testing (see EN 1822-4:2009, Annex D). The testing of high-performance filters (U16 and U17) requires methods of aerosol production with high production rates (1010 s-1 to 1011 s-1), in order to provide statistically significant measurements downstream of the filter. By adjusting the operating parameters of the aerosol generator it shall be possible to adjust the mean particle diameter of the aerosol so that it is equal to the MPPS. The concentration and the size distribution of the aerosol produced shall remain constant throughout the test. 4.2 Aerosol substances A suitable aerosol substance for the reference test method is a liquid with a vapour pressure which is so low at the ambient temperature that the size of the droplets produced does not change significantly due to evaporation over the time scale relevant for the test procedure (typically max. 5 s). SIST EN 1822-2:2010
EN 1822-2:2009 (E) 6 Possible substances include but are not limited to: DEHS; PAO; Paraffin oil (low viscosity). The most critical properties of a possible aerosol substance are: Index of refraction; Vapour pressure; Density; which should not differ too much from the values given for the three substances suggested in Table 1. NOTE Standard laboratory safety regulations should be observed when handling these substances. It should be ensured by means of suitable exhaust systems and air-tight aerosol ducting systems that the test aerosols are not inhaled. In case of doubt the safety data sheets for the appropriate substances should be consulted. SIST EN 1822-2:2010
EN 1822-2:2009 (E) 7 Table 1 — Important data for aerosol substances at 20 °C
DEHS PAO a Paraffin oil (low visc.) Chemical designation Sebacic acid-bis(2-ethylhexyl) ester Poly-Alpha-Olephin (e.g. CAS b No. 68649-12-7) Mixture (e.g. CAS # 64742-46-7)Trivial name Diethylhexylsebacyte Polyalphaolefin Paraffinoil Density (kg/m3) 912 800 – 820 (820 c) 843 Melting point (K) 225 ~ 280 259 Boiling point (K) 529 650 – 780 (674 c)
Flash point (K) > 473 445 – 500 453 Vapour pressure at 293 K (µPa) 1,9 100 – 130
Dynamic viscosity (kg/m s) 0,022 to 0,024 0,003 1 – 0,004 at 373 K (0,013 at 313 K c) (Kinematic viscosity at 373 K: 3,8 – 4,1 mm2/s) 0,026 Index of refraction/ wavelength (nm) 1,450/650 1,452/600 1,453 5/550 1,454 5/500 1,458 5/450 1,475/400 (1,455 6 c)
a
US Patents 5,059,349 [3] and 5,059,352 [4] describe and restrict the use of PAO for filter testing. Material properties of PAO as per Japan JACA Standard No. 37-2001: “The guideline of substitute materials to DOP” [5], Japan JISZ Standard No. 8901-206 [6] and ISO Standard No. 14644-3 [7]. b
CAS #, Chemical Abstracts Service Registry Number, substances have been registered in Chemical Abstracts, issued by American Chemical Society [8]. c
Data for “Emery 3004” as a specific example of a PAO. Source: Crosby, David W., Concentration produced by a Laskin nozzle generator, a comparison of substitute materials and DOP, 21st DOE/NRC Nuclear Air Cleaning Conference [9].
4.3 Producing monodisperse aerosols 4.3.1 Condensation methods 4.3.1.1 General Condensation methods are preferred for the creation of monodisperse aerosols, i.e. the particles are formed by condensation from the vapour phase. It is necessary to distinguish between heterogeneous and homogeneous condensation. SIST EN 1822-2:2010
EN 1822-2:2009 (E) 8 4.3.1.2 Heterogeneous condensation 4.3.1.2.1 General In the case of heterogeneous condensation the vapour condenses at a relatively low level of supersaturation onto very small particles which are already present, the so-called condensation nuclei. The size distribution of the resultant aerosol has a geometrical standard deviation between σg= 1,05 and σg = 1,15. Aerosol generators which operate using the principle of heterogeneous condensation are the Sinclair-LaMer generators (Figure 1) and the Rapaport-Weinstock generator (Figure 2). 4.3.1.2.2 Sinclair-LaMer aerosol generator (Figure 1)
A simple nebuliser operated with nitrogen nebulises a weak aqueous solution of sodium chloride. After large water drops have been excluded in a drop eliminator, the smaller droplets are passed into a diffusion drier where they vaporise. The resultant sodium chloride aerosol is then passed into a vessel containing the actual aerosol substance, where it becomes saturated with the vapour of this substance. The aerosol vapour mixture is then passed through a re-heater, and then on through a condensation chimney, where the vapour condenses on the salt particles, forming a homogeneous droplet aerosol (see also [10]).
Key 1 Nitrogen supply 2 Nebuliser 3 Drop eliminator 4 Diffusion drier 5 Thermostatic oven 6 By-pass valve 7 Flow meter 8 Re-heater 9 Condensation chimney 10 Aerosol Figure 1 — Structure of the Sinclair-LaMer aerosol generator The vessel containing the aerosol substance is contained in a thermostatic oven, whose temperature can be adjusted so as to regulate the amount of vapour and the diameter of the particles. A part of the sodium SIST EN 1822-2:2010
EN 1822-2:2009 (E) 9 chloride aerosol can also be diverted past the oven using the by-pass valve, and added to the flow again before the re-heater. This makes it possible to achieve a relatively rapid drop in the vapour concentration in the re-heater, and thus a reduction in the particle diameter.
The rates of particle production which can be achieved by means of this type of generator are in the order of 108 s-1; the particle diameter can be adjusted between approximately 0,1 µm and 4 µm. 4.3.1.2.3 Rapaport-Weinstock generator (Figure 2) An aerosol substance is nebulised through a nozzle, either as a pure substance or in solution, and the resultant polydisperse aerosol is then vaporised along the heated section of a glass tube. Residual nuclei of the impurities in the material remain.
Key 1 Liquid reservoir 2 Compressed air 3 Nebuliser 4 Vaporisation section 5 Thermostat 6 Condensation section 7 Aerosol Figure 2 — Structure of the Rapaport and Weinstock aerosol generator In the subsequent condensation section the aerosol substance then condenses on these nuclei to form a mondisperse aerosol (see also [11]). The particle diameter of this aerosol is determined by the mixing ratio of aerosol substance and solvent. The final aerosol contains the solvent used (e.g. Propanol) as a vapour. SIST EN 1822-2:2010
EN 1822-2:2009 (E) 10 Generators of this type achieve particle production rates of 109 s-1; the particle diameter can be adjusted between approximately 0,1 µm and 1,5 µm. 4.3.1.3 Homogeneous condensation At higher levels of super-saturation, clusters of vapour molecules form spontaneously without the presence of condensation nuclei, and these then grow to particles which are some nanometres in diameter (homogeneous condensation). Larger particles then form as a result of coagulation of these particles with one another. The resultant size distribution has a standard deviation of σg ~ 15 independent of the median particle size, and can thus only be referred to as quasi-monodisperse. On the other hand, rates of production of particles achieved can be as much as two orders of magnitude larger than those possible using heterogeneous condensation (more than 1011 s-1). Figure 3 shows the structure of a free-jet condensation aerosol generator which makes use of this principle.
Key 1 DEHS tank 2 Pump 3 Flow controller 4 Nitrogen 5 Ultra-sonic nebuliser 6 Thermostat 7 Vaporisation pipe with heater and insulation 8 Sheath air 9 Nozzle 10 Sintered metal plate 11 Coagulation section 12 Aerosol Figure 3 — Set-up of a free-jet condensation aerosol generator SIST EN 1822-2:2010
EN 1822-2:2009 (E) 11 An aerosol substance is delivered by a pump at a defined flow rate to an ultrasonic nebuliser. The relatively large droplets which are produced (> 20 µm) are then vaporised in a heated pipe. The concentration of residual nuclei is so low that they do not influence the subsequent homogeneous condensation process. The hot stream of nitrogen carrying the vapour then passes through a nozzle into a cold, laminar flow of sheath air. The turbulent mixing of the free jet with the cold air produces the super-saturation necessary for the homogeneous condensation. The particle size and particle concentration can be adjusted by varying the volume flow rates of the aerosol substance (DEHS), nitrogen and envelope air. 4.3.2 Particle size classification Using a differential mobility analyser as described in 5.3 it is possible to separate a fraction with almost the same electrical mobility from a polydisperse aerosol (see also [12]). Provided all these particle carry only a single electrical charge, then this mono-mobile fraction is also monodisperse. If necessary, larger particles which carry a multiple charge, and which thus have the same electrical mobility as the single-charged particles, must be removed from the polydisperse input aerosol by suitable means. Since the proportion of singly-charged particles in the relevant size-range is less than 10 %, from which only a narrow size-band is selected, then the number concentration of the monodisperse output aerosol is lower than the input concentration by a factor of at least 100. In consequence this method of producing monodisperse aerosols is only suitable for the measurement of the fractional efficiency of the filter medium (see EN 1822-3). The degree of monodispersity achieved by this method can be described by a geometrical standard deviation of σg < 1,1. In practise, however, the operating parameters are often amended to increase the particle concentration, at the expense of a greater standard deviation. 4.4 Generating polydisperse aerosols Polydisperse liquid aerosols are usually produced by nebulising the aerosol substance through a binary nozzle using compressed air. A subsequent inertial separator, in the form of baffle plates or a cyclone separator serves to precipitate larger particles and to reduce the range of the size distribution. The geometrical standard deviation of the distribution generated lies between 1,6 and 2,5. The particle diameter can be influenced to a small degree by changing the operating pressure of the nozzle. Greater influence on the particle size is usually achieved by dissolving the aerosol in a volatile solvent (e.g. Propanol) before nebulisation. When the solvent evaporates it leaves behind particles whose size is governed by the ratio of aerosol substance to solvent which is used.
It is comparatively simple to increase the particle production rate by using a number of jets in parallel. The maximum rate of particle production which can be achieved using one nozzle is 5 x 1010 s-1.
NOTE A typical jet nebuliser is described for example in [13]. 4.5 Neutralisation of aerosols
Since electrically charged particles are removed more effectively by filters than are uncharged particles, electrically neutral particles should be used for testing filters. A neutral state of charge is generally understood to be the stationary equilibrium achieved when charged aerosol particles are brought together with a sufficient number of positive and negative gas ions. This is usually carried out by ionising the carrier gas of the aerosol using a radioactive source or by corona discharge. The low level of residual charge in the aerosol after this neutralisation can be neglected for the filtration process. Aerosol particles become electrically charged when there is a division of charges in the course of production (e.g. nebulisation). This is above all the case when polar liquids such as water (or, to a lesser extent Propanol) are nebulised. In the case of pure DEHS or DOP relatively few charges occur. Condensation processes without prior nebulisation generate virtually charge-free aerosols, which do not have to be neutralised. SIST EN 1822-2:2010
EN 1822-2:2009 (E) 12 In order to ensure neutralisation of the highly-concentrated aerosols needed for testing filters, it is necessary for the neutralisers to have a sufficiently high concentration of ions. The aerosol shall also be kept in the ionising atmosphere for a sufficiently long period (see also [14]). 4.6 Minimum performance parameters for aerosol generators a) Generators for testing media: Particle production rate: 106 s-1 to 108 s-1 Particle diameter adjustable over the range: 0,04 µm to 1,0 µm b) Generators for testing filter elements: Particle production rate: 108 s-1 to 1011 s-1 Particle diameter adjustable over the range: 0,08 µm to 1,0 µm 4.7 Sources of error Care shall be taken that the pressure of the gas supply for the aerosol generators (compressed air, Nitrogen) remains constant. The supplied gas shall be free of particles and of a sufficiently low humidity. Nebuliser nozzles may gradually become blocked, leading to unnoticed changes in the nebulisation characteristics. Condensation generators are sensitive to variations in temperature along the condensation path, arising for example due to draughts. NOTE Aerosol substances which are subjected to higher temperatures for longer periods will undergo changes and should be exchanged at regular intervals.
4.8 Maintenance and inspection Aerosol generators shall be maintained regularly in accordance with the manufacturer's instructions. Suitable measuring systems in accordance with Clause 5 shall be used to check the size distribution and the constancy of the production rate at the intervals specified in Clause 6. 5 Measuring devices 5.1 Optical particle counters 5.1.1 Operation In an optical particle counter the particles are led individually through an intensively illuminated measuring volume. When passing through the measuring volume, the particle scatters light, which is detected at a defined spatial angle by a photo detector and transformed into an electrical pulse. The level of this pulse allows corresponds with the size of the particle, and the number of pulses per unit time with the particle concentration in the air volume analyzed. Figure 4 shows the general structure of an optical particle counter with a laser light source as an example. SIST EN 1822-2:2010
EN 1822-2:2009 (E) 13 5.1.2 Minimum performance parameters
Measuring range for the particle size: 0,1 µm to 2,0 µm (for 100 % counting efficiency) Minimum number of particle size classes between 0,1 µm and 0,5 µm: for testing the filter medium five size classes; for testing the filter element two size classes. Zero count rate < 1 min-1.
Key 1 Reference detector 2 Laser mi
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