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BS EN 1822-3-1998 High efficiency air filters (HEPA and ULPA). Testing flat sheet filter media.pdf

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BS EN 1822-3-1998 High efficiency air filters (HEPA and ULPA). Testing flat sheet filter media.pdf

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Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI BRITISH STANDARD High efficiency air filters (HEPA and ULPA) Ð Part 3: Testing flat sheet filter media 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 ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| BS EN 1822-3:1998 BS EN 1822-3:1998 标准分享网 www.bzfxw.com 免费下载 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. Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI 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. 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 Amendments issued since publication Amd. No. Date Text affected © BSI 1998 ISBN 0 580 29839 6 EUROPEAN STANDARD NORME EUROPE ENNE EUROPAÈ ISCHE NORM EN 1822-3 May 1998 ICS 23.120 Descriptors: air filters, cleaning equipment for gases, ventilation, air conditioning, tests, effectiveness, aerosol, particle counters, testi ng 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: PruÈ fung 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. Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI 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 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI Page 2 EN 1822-3:1998 标准分享网 www.bzfxw.com 免费下载 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 Foreword 1 Scope 2 Normative references 3 Definitions and quantities 4 Description of the test method 5 Sampling of sheet filter media 6 Test apparatus 6.1 Test arrangements for testing with monodisperse test aerosol 6.2 Test arrangements for testing with a polydisperse test aerosol 6.3 Test filter mounting assembly 6.4 Determination of the filter medium face velocity 7 Requirements for the test air 8 Testing procedure 8.1 Preparatory checks 8.2 Procedure 8.3 Reference test method 9 Evaluation 10 Test report 11 Maintenance and inspection of the test apparatus Annex A (informative) Example of an application with evaluation Page 2 3 3 3 3 3 5 5 5 5 9 9 9 9 10 10 10 10 11 12 © BSI 1998 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI Page 3 EN 1822-3:1998 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. 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. 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. 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. © BSI 1998 Page 4 EN 1822-3:1998 标准分享网 www.bzfxw.com 免费下载 Table 1 Ð Quantities Term Symbol Unit Equation for the calculation Measured variables Exposed area Test volume flow rate A cm2 VÇ cm3/s Pressure drop Dp Pa Mean particle diameter Particle number Sampling volume flow rate Sampling duration dÄ p mm N Ð VÇ s cm3/s t s Calculated quantities Filter medium velocity u cm/s u = VÇ A Mean pressure difference Particle number concentration Penetration for particles in size range i Mean penetration Mean efficiency Dp Pa ∑ Dp = 1 n i n =1 Dpi cN cm23 cN = N VÇ S 3 t Pi 1) Pi = cN,d,i cN,u,i 2) P 1) ∑ P = 1 n n i=1 Pi E 1) E=12P Number of particles for the upper or lower limit of N95% Ð the 95 % level of confidence See clause 7 of EN 1822-2:1998 Penetration as upper limit value for the 95 % level of P95%,i 1) confidence Mean penetration as upper limit value for the 95 % P95% 1) level of confidence Mean efficiency as lower limit value for the 95 % level E95% 1) of confidence P95%,i = cN,d,95%,i cN,u,95%,i 2) ∑ P95% = 1 n n i=1 P95%,i E95% = 1 2 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. Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI © BSI 1998 Page 5 EN 1822-3:1998 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI 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. 1) Actually, the adjustment gives the mode of number distribution. This can be taken as equal to the median value with sufficient accuracy. © BSI 1998 Page 6 EN 1822-3:1998 标准分享网 www.bzfxw.com 免费下载 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI 1 Filter 2 Pressure valve 3 Solenoid valve 4 Jet nebulizer 5 Neutralizer 6 Differential mobility analyser 7 Needle valve 8 Test filter mounting assembly 9 Differential pressure gauge 10 Dilution system 11 Condensation nucleus counter 12 Measuring equipment for absolute pressure, temperature and relative humidity 13 Volume flow rate meter 14 Vacuum pump 15 Computer for control and data storage Figure 1 Ð Set-up for testing with monodisperse test aerosols © BSI 1998 Page 7 EN 1822-3:1998 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI 1 Filter 9 Needle valve 2 Pressure reduction valve 10 Vacuum pump 3 Jet nebulizer 11 Measuring equipment for absolute 4 Neutralizer pressure, temperature and relative 5 Test filter mounting assembly humidity 6 Differential pressure gauge 12 Volume flow rate meter 7 Dilution system 13 Computer for control and data storage 8 Optical particle counter Figure 2 Ð Set-up for testing with polydisperse test aerosols © BSI 1998 Page 8 EN 1822-3:1998 标准分享网 www.bzfxw.com 免费下载 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI 1 Upper section (movable) 2 Lower section (fixed) 3 Inlet for the test aerosol 4 Outlet for the test aerosol 5 Upstream sampling part 6 Downstream sampling part 7 Measurement points for pressure difference Figure 3 Ð Example of a test filter mounting assembly © BSI 1998 Page 9 EN 1822-3:1998 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI 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 representative number particle concentrations. Given the small particle sizes to be measured in the testing, isokinetic sampling is not absolutely necessary at this point. The connections from the sampling point to the measuring apparatus shall be kept clean, shall be easy to keep clean, resistant to corrosion, shall conduct electricity and shall be earthed. In order to avoid the loss of particles it is important that the connections are short. The inclusion of disturbances in the line such as valves, constrictions, etc. shall be avoided. 6.4 Determination of the filter medium face velocity The filter medium velocity is not measured directly, but is determined by dividing the test volume flow rate by the exposed area in the test filter mounting assembly. For this, the exposed filter medium area needs to be known with an accuracy of ±2 %. Depending on the positioning of the extraction point on the downstream side relative to the measurement point for the test volume flow rate, it may be necessary to include the partial flow extracted for the particle counter in the calculation of the test volume flow rate. The volume flow rate can be measured using a floatmeter, a thermal mass flow meter, or other measuring equipment which can be calibrated. The minimum performance data are: measuring range: accuracy: reproducibility: up to 800 cm3/s; < 5 % of measured value; < 1 % of measured value. 7 Requirements for the test air Before mixing with the test aerosol, the test air shall be so prepared that its temperature, relative humidity and purity shall be in accordance with the requirements specified in 6.2 of EN 1822-1:1998. The test air shall be cleaned of solid or liquid components using a high efficiency filter (for example, a commercially available cartridge filter), the size of which shall be determined according to the maximum test volume flow rate. 8 Testing procedure 8.1 Preparatory checks After switching on the test apparatus prior to testing the sheet filter medium, the following parameters shall be checked or registered. Ð Readiness for use of the measuring equipment Warming-up times specified by the manufacturers of measuring equipment shall be adhered to; condensation nucleus counters shall be filled with operating fluid; the volume flow rates through the measuring equipment shall be correct. Should the equipment manufacturers recommend further routine inspections before the measurements, then these shall also be carried out. Ð Zero count rate of the particle counter The zero count rate shall be checked by measuring the downstream particle number concentration with the aerosol generator switched off and the filter medium in position. Ð Purity of the test air The purity of the test air shall be checked by measuring the upstream particle number concentration with the aerosol generator switched off. Ð Absolute pressure, temperature and relative humidity of the test air The values of these parameters shall be registered in the test volume flow on the downstream side of the test filter mounting assembly. If any of these parameters lie outside the ranges specified in EN 1822-1 and EN 1822-2, then appropriate corrective measures shall be undertaken. Reference filter medium measurement It is useful to establish reference filter media samples of different filter classes for pressure difference and for efficiency measurements. Immediately after the checks mentioned above, the measurement of a reference filter medium of the same class as the medium to be tested shall be performed. Trends established by such repeated tests will provide information about the overall repeatability of the test system (test system drift/damages and faults in the test system). © BSI 1998 Page 10 EN 1822-3:1998 标准分享网 www.bzfxw.com 免费下载 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI 8.2 Procedure Following the preparatory steps specified in 8.1, the test specimen shall be placed in the test filter mounting assembly. It shall be established that the measuring range of the instrumentation employed comfortably includes the minimum of the efficiency particle size curve and thus the position of the most penetrating particle size (MPPS). 8.2.1 Measurement of the pressure drop The pressure drop across the filter medium shall be measured with pure test air before the filter is loaded with aerosol. The test volume flow rate shall be set up with such accuracy that the flow rate values for the individual samples of the filter medium do not vary by more than ±2 % from the required value. The measurements shall be made when the system has reached a stable operating state. 8.2.2 Testing with a monodisperse test aerosol The test aerosol shall be mixed homogeneously with the test air (see 6.3). To determine the particle size efficiency, at least six approximately logarithmically equidistant interpolation points in the range of the particle sizes to be tested shall be determined. Using the differential mobility analyser six (quasi)-monodisperse test aerosols shall be generated in succession with the appropriate mean particle diameters, and their number concentrations shall be measured on the upstream and downstream sides of the filter medium, either simultaneously using two condensation nucleus counters working in parallel, or successively using one condensation nucleus counter first on the upstream and then on the downstream side. In the second case, a flushing period for the CNC shall be included, so that, before beginning the measurement on the downstream side, the particle number concentration at the condensation nucleus counter has fallen to a level such that the particles on the downstream side of the filter medium can be registered reliably. 8.2.3 Testing with a polydisperse test aerosol As an alternative to testing with a monodisperse test aerosol it is also possible to measure the number concentration and the number distribution of a polydisperse test aerosol at at least six approximately logarithmically equidistant interpolation points in the range of the particle size to be tested. Optical particle counters shall be used to count the particles. Care shall be taken to ensure that, in particular when measuring the number concentration and number distribution on the upstream side, tolerable coincidence errors are not exceeded. Furthermore the resolution of the optical particle counter shall be sufficient to meet the measuring requirements. 8.3 Reference test method The reference test method (see 6.4.4 of EN 1822-1:1998) is the test procedure according to 8.2.2. 9 Evaluation The test described in clause 8 shall be carried out consecutively on the five samples of the filter medium. For the pressure difference, the arithmetic mean of the results of the individual measurements shall be calculated. The evaluation of the particle counts shall take into account the particle counting statistics as specified in clause 7 of EN 1822-2:1998. There the calculation of the particle size penetration and efficiency shall make use of the less favourable of the limit values of the confidence interval. For each of the six or more interpolation points of the efficiency curve, the following arithmetic means shall be calculated from the individual measurements: Ð mean efficiency for the particles counted; Ð mean efficiency as lower limit for the 95 % confidence interval. The values of these efficiencies shall be presented as lines on a graph. Either using a suitable mathematical fitting method or a graphical method, the particle size shall be determined at the minimum of the curve for the mean efficiency as lower limit for the 95 % confidence interval. In this way, both the quality of the measurements and also statistical uncertainties involved with the procedures for measuring with low numbers of particles are allowed for. The particle size at which the efficiency is at a minimum is known as the MPPS (most penetrating particle size), and shall be recorded together with the appropriate value of the efficiency at that particle size. An example of application with evaluation is provided in annex A. 10 Test report The test report for the testing of the sheet filter medium shall contain at least the following information: Ð general details concerning the test: Ð designation of the filter medium tested; Ð number of samples; Ð filter medium velocity; Ð designation of the particle measuring equipment used; Ð designation of the test aerosol used; Ð details of the test results: Ð mean pressure difference across the filter medium at the start of the testing; Ð most penetrating particle size (MPPS); Ð efficiency at this particle size; Ð table giving the values of the mean efficiency as the lower limit value for the 95 % confidence interval, in accordance with EN 1822-2 (see also Table A.3); Ð diagram showing the mean efficiency and the lower limit value for the 95 % confidence interval as a function of the particle size, in accordance with EN 1822-2 (see also Figure A.1). © BSI 1998 11 Maintenance and inspection of the test apparatus The following work on the components and measuring equipment of the test apparatus shall be carried out at least at the following specified intervals (or more frequently). The successful carrying-through of the annual instrument calibration shall be documented with individual calibration protocols. Components Nature and frequency of the maintenance and inspection Operating materials Daily checks Exchange after consumption Aerosol generators Monthly cleaning Volume flow rate meter Annual testing and zero point control, or after each change Aerosol lines Annual cleaning Filters for test air Exchanged annually Waste air filter Exchanged annually Parts of the test apparatus at under-pressure Testing for leaks required if the zero count rate of the particle counter is unsatisfactory Switching valve between the test points (if installed) Annual testing for leaks Otherwise, all components and measuring equipment of the test apparatus shall be maintained and checked at the intervals specified in Table 2 of EN 1822-2:1998. Page 11 EN 1822-3:1998 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI © BSI 1998 Page 12 EN 1822-3:1998 标准分享网 www.bzfxw.com 免费下载 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI Annex A (informative) Example of an application with evaluation A.1 Testing the sheet filter medium After completing the adjustments and checks on the parameters as specified in 8.1, the pressure drop is measured for each of the specimens of the filter medium and the particles counts determined at the given filter medium face velocity. The following example of measurements shows the results of a test with a monodisperse test aerosol using the total counting procedure for a sample of the filter medium. A.1.1 Measurement of the pressure difference The pressure drop across the filter medium is measured in accordance with 8.2.1. Test conditions: exposed area: test air volume flow rate: filter medium face velocity: Test result: pressure difference: A = 100 cm2 VÇ = 175 cm3/s u = 1,75 cm/s Dp1 = 109 Pa A.1.2 Particle counting When testing with a monodisperse test aerosol, the particle counting is in accordance with 8.2.2. For each mean particle diameter dÄ p of the six or more interpolation points for the efficiency curves, the upstream and downstream number particle concentrations (cN,u; cN,d) is measured. The number concentrations are available as a rule as direct measurements from the particle counters and can be used for the further evaluation without change. The determination is done using the equations for calculation according to clause 3. In order to take into account the particle counting statistics as specified in clause 7 of EN 1822-2:1998, the downstream particle number Nd is also determined for the evaluation. Test conditions: filter medium face velocity: u = 1,75 cm/s particle measuring device: condensation nucleus counter test aerosol: DEHS, monodisperse Test result: The measurement results and the values calculated for the particle size penetration P1 are contained in Table A.1. A.2 Calculation of the arithmetic means At least five samples of the sheet filter medium are tested. From the results of the individual measurements (see A.1 as an example for one sample) arithmetic means are then calculated. The following evaluation can be carried out for both particle counting methods in the same manner. A.2.1 Mean pressure difference Tests results for the measurement of the pressure difference across the five samples of the filter medium at the given filter medium velocity u = 1,75 cm/s: Pressure difference: Dpi = 109,1 Pa; 110,1 Pa; 109,4 Pa; 109,8 Pa; 109,6 Pa Mean pressure difference: Dp = 109,6 Pa A.2.2 Mean efficiency E For the calculation of the mean efficiency E for each interpolation point of the efficiency curve, the mean penetration P is first determined from the individual penetrations Pi for the five samples of the filter medium. The calculations and results are shown in Table A.2. A.2.3 Mean efficiencies E95% as lower limit values for the 95 % confidence interval The calculation of the mean efficiency E95% as lower limit value for the 95 % confidence interval takes into account the specifications for the particle counting statistics contained in clause 7 of EN 1822-2:1998, in accordance with which the least favourable limit value of the confidence interval is determined in each case and this value used for the calculations. In the example shown, the measurements of the particle number and number concentration on the upstream side were not corrected statistically. The large numbers of particles mean that the influence of statistical uncertainty can be neglected, i.e. for this example cN,u,95%,i = cN,u,i. The penetration P95%,i is calculated taking into account the corresponding calculated value for the downstream number concentration cN,d,95%,i with the less favourable of the values of the particle number for the 95 % confidence interval Nd,95%,i. From the measurements on the five samples of the filter medium the mean penetration P95% are first calculated as the upper limit value for the 95 % confidence interval. From this mean efficiency, E95% is calculated as the lower limit value for the 95 % confidence interval for each interpolation point of the efficiency vs. particle size curve. The calculated values and the results are shown in Table A.3. A.3 Representation of the efficiency curve For each interpolation point with the mean particle diameter dÄ p, the values of the mean efficiency E and the values of the mean efficiencies E95% are presented in a diagram as curves of efficiency vs. particle size. For the example shown, the following values for the minimum of the curve (Figure A.1) can be determined: Ð most penetrating particle size (MPPS): 0,16 mm; Ð efficiency for this particle size: 99,997 5 %. © BSI 1998 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI Page 13 EN 1822-3:1998 Table A.1 Ð Measurement results and calculated values of the particle counting dÄ p 0,080 mm 0,100 mm 0,125 mm 0,160 mm 0,200 mm 0,250 mm cN,u,1 2,21 3 106 cm23 1,46 3 106 cm23 8,72 3 105 cm23 4,96 3 105 cm23 3,21 3 105 cm23 2,02 3 105 cm23 cN,d,1 3,74 3 101 cm23 2,80 3 101 cm23 2,06 3 101 cm23 1,17 3 101 cm23 7,12 3 100 cm23 3,52 3 100 cm23 Nd,1 3 000 2 228 1 653 951 568 264 P1 0,001 69 % 0,001 92 % 0,002 36 % 0,002 37 % 0,002 22 % 0,001 74 % Index ªuº refers to samples from the upstream side. Index ªdº refers to samples from the downstream side. dÄ p P1 P2 P3 P4 P5 P E Table A.2 Ð Calculated values for the determination of the mean efficiency 0,080 mm 0,100 mm 0,125 mm 0,160 mm 0,200 mm 0,250 mm 0,001 69 % 0,001 92 % 0,002 36 % 0,002 37 % 0,002 22 % 0,001 74 % 0,001 97 % 0,002 09 % 0,002 33 % 0,002 31 % 0,002 11 % 0,001 86 % 0,001 99 % 0,002 16 % 0,002 33 % 0,002 50 % 0,002 55 % 0,002 07 % 0,001 84 % 0,002 17 % 0,002 29 % 0,002 27 % 0,002 08 % 0,001 78 % 0,001 79 % 0,002 16 % 0,002 35 % 0,002 39 % 0,002 21 % 0,001 51 % 0,001 86 % 0,002 10 % 0,002 33 % 0,002 37 % 0,002 23 % 0,001 79 % 99,998 14 % 99,997 90 % 99,997 67 % 99,997 63 % 99,997 77 % 99,998 21 % Table A.3 Ð Calculated values for the determination of the mean efficiency as the lower limit value for the 95 % confidence interval dÄ p 0,080 mm 0,100 mm 0,125 mm 0,160 mm 0,200 mm 0,250 mm Nd,1 3 000 2 228 1 653 951 568 264 Nd,95%,1 3 107 2 321 1 733 1 011 615 296 P95%,1 0,001 75 0,002 00 % 0,002 47 % 0,002 52 % 0,002 40 % 0,001 95 % Nd,2 3 036 2 283 1 665 953 546 302 Nd,95%,2 3 144 2 377 1 745 1 014 592 336 P95%,2 0,002 04 % 0,002 18 % 0,002 44 % 0,002 46 % 0,002 29 % 0,002 07 % Nd,3 3 194 2 346 1 603 948 673 379 Nd,95%,3 3 305 2 441 1 681 1 008 724 417 P95%,3 0,002 06 % 0,002 25 % 0,002 44 % 0,002 66 % 0,002 74 % 0,002 28 % Nd,4 3 090 2 429 1 638 958 581 320 Nd,95%,4 3 199 2 526 1 717 1 019 628 355 P95%,4 0,001 90 % 0,002 26 % 0,002 40 % 0,002 41 % 0,002 25 % 0,001 98 % Nd,5 2 938 2 383 1 678 1 004 609 271 Nd,95%,5 3 044 2 479 1 758 1 066 657 303 P95%,5 0,001 85 % 0,002 25 % 0,002 46 % 0,002 54 % 0,002 39 % 0,001 69 % P95% 0,001 92 % 0,002 19 % 0,002 44 % 0,002 52 % 0,002 41 % 0,001 99 % E95% 99,998 08 % 99,997 81 % 99,997 56 % 99,997 48 % 99,997 59 % 99,998 01 % © BSI 1998 Page 14 EN 1822-3:1998 标准分享网 www.bzfxw.com 免费下载 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI Figure A.1 Ð Mean efficiency E (__) and E95% (- - -) as a function of the particle diameter dÄ p © BSI 1998 Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI blank Licensed copy:PONTYPRIDD COLLEGE, 05/07/2007, Uncontrolled Copy, © BSI BSI 389 Chiswick High Road London W4 4AL 标准分享网 www.bzfxw.com 免费下载 BSI Ð British Standards Institution ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| BSI is the independent national body responsible for preparing British Standards. 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