EN 1822-3

| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 1822-3:1998 The European Standard EN 1822-3:1998 has the status of a British Standard ICS 23.120 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW High efficiency air filters (HEPA and ULPA) Ð Part 3: Testing flat sheet filter media BS EN 1822-3:1998 This British Standard, having been prepared under the direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 December 1998  BSI 1998 ISBN 0 580 29839 6 Amendments issued since publication Amd. No. Date Text affected National foreword This British Standard is the English language version of EN 1822-3:1998. The UK participation in its preparation was entrusted by Technical Committee MCE/21, Filters for gases and liquids, to Subcommittee MCE/21/3, Air filters other than for air supply for IC engines and compressors, which has the responsibility to: Ð aid enquirers to understand the text; Ð present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; Ð monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled ªInternational Standards Correspondence Indexº, or by using the ªFindº facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 14, an inside back cover and a back cover. CEN European Committee for Standardization Comite EuropeÂen de Normalisation EuropaÈisches Komitee fuÈ r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels  1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1822-3:1998 E EUROPEAN STANDARD EN 1822-3 NORME EUROPE ENNE EUROPAÈ ISCHE NORM May 1998 ICS 23.120 Descriptors: air filters, cleaning equipment for gases, ventilation, air conditioning, tests, effectiveness, aerosol, particle counters, testing conditions, computation English version High efficiency air filters (HEPA and ULPA) Ð Part 3: Testing flat sheet filter media Filtres aÁ air aÁ treÁs haute efficacite et filtres aÁ air aÁ treÁs faible peÂneÂtration (HEPA et ULPA) Ð Partie 3: Essais de medias filtrants plans Schwebstoffilter (HEPA and ULPA) Ð Teil 3: PruÈfung des planen Filtermediums This European Standard was approved by CEN on 6 March 1998. 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 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 translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Page 2 EN 1822-3:1998  BSI 1998 Foreword This European Standard has been prepared by Technical Committee CEN/TC 195, Air filters for general air cleaning, the Secretariat of which is held by DIN. It deals with the performance testing of high efficiency particulate air filters (HEPA) and ultra low penetration air filters (ULPA). The complete European Standard High efficiency air filters (HEPA and ULPA) consists of the following parts: Ð Part 1: Classification, performance testing, marking; Ð Part 2: Aerosol production, measuring equipment, particle counting statistics; Ð Part 3: Testing flat sheet filter media; Ð Part 4: Determining leakage of filter elements (Scan method); Ð Part 5: Determining the efficiency of filter elements. 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 overall efficiency. Instead of mass relationships, this new technique is based on particle counting at the most penetrating particle size (MPPS; range: 0,15 mm to 0,30 mm). It also allows ultra low penetration air filters to be tested, which is not possible with the previous test methods because of their inadequate sensitivity. 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 November 1998, and conflicting national standards shall be withdrawn at the latest by November 1998. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Definitions and quantities 3 4 Description of the test method 3 5 Sampling of sheet filter media 3 6 Test apparatus 5 6.1 Test arrangements for testing with monodisperse test aerosol 5 6.2 Test arrangements for testing with a polydisperse test aerosol 5 6.3 Test filter mounting assembly 5 6.4 Determination of the filter medium face velocity 9 7 Requirements for the test air 9 8 Testing procedure 9 8.1 Preparatory checks 9 8.2 Procedure 10 8.3 Reference test method 10 9 Evaluation 10 10 Test report 10 11 Maintenance and inspection of the test apparatus 11 Annex A (informative) Example of an application with evaluation 12 Page 3 EN 1822-3:1998  BSI 1998 1 Scope This European Standard applies to high efficiency particulate air filters and ultra low penetration air filters (HEPA and 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 test aerosol, and allows a standardized classification of these filters in terms of their efficiency. This European Standard applies to testing sheet filter media used in high efficiency air filters. The procedure includes methods, test assemblies and conditions for carrying out the test, and the basis for calculating results. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to, or revisions of, any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies. EN 1822-1:1998, High efficiency air filters (HEPA and ULPA) Ð Part 1: Classification, performance testing, marking. EN 1822-2:1998, High efficiency air filters (HEPA and ULPA) Ð Part 2: Aerosol production, measuring equipment, particle counting statistics. 3 Definitions and quantities 3.1 Definitions For the purposes of this standard, the definitions according to EN 1822-1 and EN 1822-2 apply. 3.2 Quantities Table 1 contains the quantities (terms and symbols) used in this standard to represent measurement variables and calculated values. The values inserted in the equation given for these calculations should be in the units specified. 4 Description of the test method When testing the sheet filter medium, the particle size efficiency is determined using a particle counting method. The testing can use a monodisperse or a polydisperse test aerosol. The methods differ in terms of both the production of the aerosol and the particle counter used. Furthermore, the measurement of the pressure drop is made at the prescribed filter medium velocity. Specimens of the sheet filter medium are fixed in a test filter assembly and subjected to the test air flow corresponding to the prescribed filter medium velocity. The test aerosol from the aerosol generator shall be conditioned (e.g. vaporization of a solvent) then neutralized, mixed homogeneously with filtered test air and led to the test filter assembly. In order to determine the efficiency, partial flows of the test aerosol are sampled upstream and downstream of the filter medium. Using a particle counting instrument, the number concentration of the particles contained is determined for various particle sizes. The results of these measurements are used to draw a graph of efficiency against particle size for the filter medium, and to determine the particle size for which the efficiency is a minimum. This particle size is known as the ªmost penetrating particle sizeº (MPPS). When measuring the particles on the upstream side of the filter medium it may be necessary to use a dilution system in order to reduce the concentration of particles down to the measuring range of the particle counter used. Additional equipment is required to measure the absolute pressure, temperature and relative humidity of the test aerosol and to measure and control the test volume flow rate. 5 Sampling of sheet filter media The testing of the sheet filter medium shall be carried out on at least five samples. The samples shall be handled with care; the area to be tested shall be free from all folds, kinks, holes or other irregularities. All samples shall be clearly and permanently marked with the following details: a) the designation of the filter medium; b) the upstream side of the filter medium. Page 4 EN 1822-3:1998  BSI 1998 Table 1 Ð Quantities Term Symbol Unit Equation for the calculation Measured variables Exposed area A cm2 Test volume flow rate VÇ cm3/s Pressure drop Dp Pa Mean particle diameter dÄ p mm Particle number N Ð Sampling volume flow rate VÇ s cm 3/s Sampling duration t s Calculated quantities Filter medium velocity u cm/s u = VÇ A Mean pressure difference Dp Pa Dp = Dpi 1 n ∑ i = 1 n Particle number concentration cN cm 23 cN = N VÇ S 3 t Penetration for particles in size range i Pi 1) 2)Pi = cN,d,i cN,u,i Mean penetration P 1) P = Pi 1 n ∑ i = 1 n Mean efficiency E 1) E = 12 P Number of particles for the upper or lower limit of the 95 % level of confidence N95% Ð See clause 7 of EN 1822-2:1998 Penetration as upper limit value for the 95 % level of confidence P95%,i 1) 2)P95%,i = cN,d,95%,i cN,u,95%,i Mean penetration as upper limit value for the 95 % level of confidence P95% 1) P95% = P95%,i 1 n ∑ i = 1 n Mean efficiency as lower limit value for the 95 % level of confidence E95% 1) E95% = 12 P95% 1) These quantities are usually given as a percentage. 2) The index ªuº refers to upstream particle counts, and the index ªdº refers to downstream particle counts. Page 5 EN 1822-3:1998  BSI 1998 1) Actually, the adjustment gives the mode of number distribution. This can be taken as equal to the median value with sufficient accuracy. 6 Test apparatus The test apparatus to be used and the arrangement of the components and measuring equipment are shown in Figure 1 of EN 1822-1:1998. The basic details for the aerosol generation and the aerosol neutralization, together with the details of suitable types of apparatus are contained in EN 1822-2. 6.1 Test arrangements for testing with monodisperse test aerosol When testing sheet filter media with a monodisperse test aerosol, the particle number concentration is determined using a total count method with a condensation nucleus counter. The arrangement of the test apparatus is shown in Figure 1. The monodisperse test aerosol is created in a number of steps. Firstly a polydisperse primary aerosol is produced using a jet nebulizer with, for example, a DEHS/iso-propanol solution. The particles are reduced to a convenient size for the following process by evaporation of the solvent. The aerosol is then neutralized and passed to a differential mobility analyser. The quasi-monodisperse test aerosol available at the output of the differential mobility analyser is once again neutralized, and then mixed homogeneously with filtered test air in order to achieve at the test volume flow rate required for the filter medium velocity. The mean particle diameter of the number distribution is varied by adjusting the voltage between the electrodes of the differential mobility analyser1). In order to achieve a sufficiently high particle number concentration over the entire test range from 0,04 mm to 0,8 mm, it may prove necessary to use several jet nebulizers with differing concentrations of the aerosol substances in the solvent. Numerical concentrations which are too high can be adjusted by diluting the test aerosol before the test filter mounting assembly. The number concentration in the test aerosol shall be selected so that no dilution is necessary for the measurements made downstream from the filter. A pump positioned downstream draws the test aerosol through the test filter mounting assembly. This ensures that the differential mobility analyser can always operate under nearly the same conditions, independent of the pressure drop across the tested filter medium. In contrast, where the testing system operates with an over-pressure this ensures that leaks in the system do not falsify the test measurements. Particles are counted upstream and downstream from the filter using either two condensation nucleus counters in parallel, or using only one such counter to measure the upstream and downstream concentrations alternately. If the level of the upstream number concentration exceeds the measuring range of the counter then a dilution system shall be included between the sampling point and the counter. 6.2 Test arrangements for testing with a polydisperse test aerosol When testing sheet filter media with a polydisperse test aerosol, optical particle counters are used, which determine the number distribution and the number concentration of the test aerosol. The tests can be carried out directly with the polydisperse, neutralized primary aerosol. In order to cover the test range it may be necessary to use several jet nebulizers with different concentrations of the aerosol substance in the solvent. The mean particle diameter of the number distribution shall not lie outside the test range of 0,04 mm to 0,8 mm. The arrangement of the test apparatus is shown in Figure 2. Instead of the single or two parallel condensation nucleus counters, optical particle counters are used to determine the number distribution and the number concentration of the polydisperse test aerosol on the upstream and downstream sides of the filter medium. When testing with a polydisperse test aerosol and particle counting and sizing equipment, it is also necessary to ensure that the number concentration of the test aerosol is adjusted to suit the measuring range of the particle counter, if necessary by the inclusion of a dilution system. 6.3 Test filter mounting assembly The test filter mounting assembly consists of a movable upper section and a fixed lower section (an example is shown in Figure 3). The sheet filter medium shall have a circular exposed area of 100 cm2. The filter medium shall be mounted in such a way that the measurements obtained are not influenced by bypass leaks. Where seals are used for this purpose they shall not change the exposed area. The test aerosol is introduced through the inlet opening in the upper section of the test filter mounting assembly. It shall be ensured that the test aerosol to which the filter medium is exposed possesses an homogeneous local concentration over the entire passage area (standard deviation s < 10 %). An outlet for the test aerosol is provided in the base section of the test filter mounting assembly. Further connections are provided for sampling of partial flows of the test aerosol on the upstream side and downstream side to measure the particles, and also for the measurement of the pressure drop. All the materials of the test filter mounting assembly with which the test aerosol comes into contact shall be kept clean, and shall be easy to keep clean, resistant to corrosion, shall conduct electricity and shall be earthed. Stainless steel and anodized aluminium shall be used preferably. The test filter mounting assembly may have any appropriate constructional form, but shall meet all the test requirements specified in this standard. Page 6 EN 1822-3:1998  BSI 1998 1 2 3 4 5 6 7 8 9 Filter Pressure valve Solenoid valve Jet nebulizer Neutralizer Differential mobility analyser Needle valve Test filter mounting assembly Differential pressure gauge 10 11 12 13 14 15 Dilution system Condensation nucleus counter Measuring equipment for absolute pressure, temperature and relative humidity Volume flow rate meter Vacuum pump Computer for control and data storage Figure 1 Ð Set-up for testing with monodisperse test aerosols Page 7 EN 1822-3:1998  BSI 1998 1 2 3 4 5 6 7 8 Filter Pressure reduction valve Jet nebulizer Neutralizer Test filter mounting assembly Differential pressure gauge Dilution system Optical particle counter 9 10 11 12 13 Needle valve Vacuum pump Measuring equipment for absolute pressure, temperature and relative humidity Volume flow rate meter Computer for control and data storage Figure 2 Ð Set-up for testing with polydisperse test aerosols Page 8 EN 1822-3:1998  BSI 1998 1 2 3 4 5 6 7 Upper section (movable) Lower section (fixed) Inlet for the test aerosol Outlet for the test aerosol Upstream sampling part Downstream sampling part Measurement points for pressure difference Figure 3 Ð Example of a test filter mounting assembly Page 9 EN 1822-3:1998  BSI 1998 6.3.1 Measurement of pressure difference The pressure difference across the sheet filter medium is measured using differential pressure measuring equipment (see 5.6 of EN 1822-2:1998) which is attached to the upstream and downstream measuring points of the test filter mounting assembly. At the measuring points the static pressure shall be measured. The measuring points shall be arranged at right angles to the inner surface of the test filter mounting assembly so that as far as possible the measurements are not influenced by the flow rate. The inner edges of the drill holes shall be sharp-edged and free of burrs. The connections from the measurement points to the pressure gauge shall be leakproof and clean. 6.3.2 Sampling For the sampling of the test aerosol on the upstream and downstream sides it shall be ensured that the partial flows contain repr