1、 Institute of Environmental Sciences and Technology IEST-RP-CC007.3 Contamination Control Division Recommended Practice 007.3 Testing ULPA Filters Arlington Place One 2340 S. Arlington Heights Road, Suite 620 Arlington Heights, IL 60005-4510 Phone: (847) 981-0100 Fax: (847) 981-4130 E-mail: informat
2、ioniest.org Web: www.iest.org 2 Copyrighted material Institute of Environmental Sciences and Technology IEST-RP-CC007.3 This Recommended Practice was prepared by and is under the jurisdiction of Working Group 007 of the IEST Contamination Control Division (WG-CC007). The following WG voting members
3、contributed to the development of this edition of this Recommended Practice. R. Vijayakumar, WG-CC007 Chair, AERFIL Anthony Caughron, TEC Services, Inc. Daniel Dennison, NNE Pharmaplan, Inc. Keith Flyzik, Micro-Clean, Inc. Donna Kasper, Hollingsworth b) the test aerosol; c) the test volume flow rate
4、. Prior to testing filters according to this RP, the most penetrating particle size (MPPS) should be determined. The determination can be made for the filter medium in flat sheet form, provided that the test is conducted with an aero-sol as defined in section 4.2.9. The test is performed at the same
5、 velocity as the average velocity through the medium in the assembled filter at the test volume flow rate. CAUTION: Testing in accordance with this RP may involve hazardous materials, operations, and equipment. This RP does not purport to address the safety problems associated with its use. It is th
6、e responsibility of the user to consult and establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use of this RP. The methodology described in this RP may be applied for particle-counter testing of filters outside the efficiency and p
7、article size range covered in the document. 8 Copyrighted material Institute of Environmental Sciences and Technology IEST-RP-CC007.3 2 REFERENCES The following documents are incorporated into this RP to the extent specified herein. Users should apply the most recent editions of the references. 2.1
8、Reference documents ANSI/ASHRAE Standard 52.2-2012: Method of Testing General Ventilation Air-Cleaning Devices for Removal Effi-ciency by Particle Size Fluid Meters: Their Theory and Application (ASME) ASME-N510: Testing of Nuclear Air-Treatment Systems IEST-RP-CC001: HEPA and ULPA Filters IEST-RP-C
9、C014: Calibration and Characterization of Optical Airborne Particle Counters IEST-RP-CC021: Testing HEPA and ULPA Filter Media IEST-RP-CC031: Method for Characterizing Outgassed Organic Compounds from Cleanroom Materials and Components TAPPI-T1205: Dealing with Suspect (Outlying) Test Determinations
10、 2.5 Sources and Addresses ASHRAE American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. 1791 Tullie Circle, NE Atlanta, Georgia 30329, USA Phone: 404-636-8400 Fax: 404-321-5478 www.ashrae.org ASME International American Society of Mechanical Engineers Three Park Avenue New
11、 York, NY 10016-5990, USA Phone: 800-843-2763 Fax: 973-882-1717 www.asme.org IEST Institute of Environmental Sciences and Technology Arlington Place One 2340 S. Arlington Heights Road, Suite 620 Arlington Heights, IL 60005-4510 Phone: 847-981-0100 Fax: 847-981-4130 www.iest.org TAPPI Technical Assoc
12、iation of the Pulp and Paper Industry 15 Technology Parkway South Norcross, Georgia 30092 Phone: 770-446-1400 Fax: 770-446-6947 www.tappi.org IEST-RP-CC007.3 Institute of Environmental Sciences and Technology Copyrighted material 9 3 TERMS AND DEFINITIONS The following terms have special meaning in
13、the context of this RP. aerosol A gaseous suspension of fine solid or liquid particles. airflow Airflow refers to volumetric flow rather than mass flow. Tests are run at the manufacturer-rated airflow or other airflow as agreed upon by the customer and supplier. challenge aerosol An aerosol derived
14、from the selected aerosol source material and used as the leak-test challenge for a filter leak test. Challenge aerosols may be produced by a variety of methods, with the choice determined by the aerosol type and the particle size characteristics. correlation ratio The ratio of downstream counts to
15、upstream counts with no filter in the test system. For sequential counting systems, the correlation ratio represents the differences in the upstream and downstream sampling systems, such as: particle losses in sample lines and test duct diluter (if used) sample times For simultaneous counting system
16、s, the correlation ratio represents the same factors as for sequential counting sys-tems, as well as the differences between the different particle counting instruments used upstream and downstream, such as: sample flow rate counting efficiency DOP or DEHP Dioctyl phthalate (DOP) or di(2-ethylhexyl)
17、 phthalate (DEHP); CAS# 117-81-7. DOS or DEHS Dioctyl sebacate (DOS) or di(2-ethylhexyl) sebacate (DEHS); CAS# 122-62-3. electret filter media Media made of fibers that carry electrical charge on their surfaces. HEPA (high-efficiency particulate air) filter An extended-medium, dry-type filter in a r
18、igid frame when tested at rated airflow having a minimum particle collec-tion efficiency of 99.97% for 0.3-m mass median diameter particles of DOP when tested in accordance with MIL-STD-282. NOTE: The foregoing is the traditional definition for the HEPA filter. Changes in the filter manufacture, end
19、-user requirements, and testing have introduced products that vary parametrically from filters that have been considered standard according to this definition. Additional information on this topic is given in IEST-RP-CC001. microspheres (or PSL) Monodisperse or polydisperse sized particles usually m
20、ade of polystyrene latex (PSL). Monodisperse particle size is traceable to the National Institute of Standards and Technology (NIST) or other national standards bodies with re-spect to the diameter. NOTE: PSL refers to a common type of highly uniform spheres, or a suspension thereof, used to generat
21、e a solid aerosol. PSL is useful for leak testing filters where other aerosols may contaminate the filters in an unacceptable manner. The term latex refers to an emulsion in water of finely divided particles of synthetic rubber, plastic, or other elastomer, and is not to be confused with natural rub
22、ber latex. 10 Copyrighted material Institute of Environmental Sciences and Technology IEST-RP-CC007.3 monodisperse aerosol An aerosol with a narrow particle size distribution that has a geometric standard deviation less than 1.10. For the procedures in this document, any aerosol with at least 90% of
23、 the particles between 0.1 and 0.2 m is considered a monodisperse aerosol. most penetrating particle size (MPPS) The particle size at which a given filter has its highest penetration (or lowest efficiency); i.e., the worst-case particle size with respect to filtration efficiency. From filtration the
24、ory, efficiency is higher for particle sizes smaller or larger than the MPPS. In practice, the MPPS of a filter is considered to be within a measured size range typical in commercial instruments rather than at one unique particle size. national metrology institute (NMI) An organization providing nat
25、ional or international primary test standards used in the unbroken chain of traceability of test equipment. NOTE: Traceability to national metrology institute standards does not always require the use of the NMI of the country in which a calibration laboratory is located. PAO (4 cSt poly-alpha-olefi
26、n) A grade of PAO with a viscosity of 4 centistokes at 100 C. With reference to filter testing, PAO also refers to a poly disperse aerosol of the described material. particle count The number of particles detected in a given volume of air (or in a given time period for a stable instrument sample flo
27、w rate). The number may be determined by counting discrete particles using a particle counter, or it may be deduced by calibration of a monotonic response (such as the photometric calibration of a condensation nucleus counter) of the instrument to a known concentration standard. particle counter An
28、instrument capable of resolving responses from individual particles (e.g., an optical particle counter or condensa-tion particle counter). particle size The apparent maximum linear dimension of a particle in the plane of observation as observed with an optical micro-scope, or the equivalent diameter
29、 of a particle detected by automatic instrumentation. The equivalent diameter is the diameter of a reference sphere having known properties and producing the same response in the sensing instrument as the particle being measured. penetration The ratio of the number of particles exiting the filter to
30、 the number of particles entering the filter, per unit time, expressed as a percentage for a stated particle size range. observed penetration The penetration calculated from observed counts. true mean penetration The penetration that would be calculated from the average observed counts, if the tests
31、 were repeated indefinitely. UCL and LCL penetration The 95% upper confidence limit (UCL) penetration and 95% lower confidence limit (LCL) penetration are val-ues statistically calculated from the observed counts. There is a 95% confidence that the true mean penetration is between the UCL and LCL pe
32、netrations. polydisperse aerosol An aerosol that does not meet the definition of a monodisperse aerosol. For the procedures outlined in this docu-ment, the statistical mode of a polydisperse aerosol distribution should be between 0.10.2 m. polystyrene microspheres (PSL) (see microspheres) sequential
33、 counting systems Test systems in which particles are counted by the same counter or counters both upstream and downstream of the filter. The counters are sequentially connected to either side of the filter, once or several times. Sequential counting systems are characterized by the need for stable
34、aerosol and by reduced problems in correlating counters. IEST-RP-CC007.3 Institute of Environmental Sciences and Technology Copyrighted material 11 simultaneous counting systems Test systems in which particles are counted simultaneously upstream of the filter, with a counter or counters dedicated to
35、 upstream counting, and downstream of the filter, with a counter or counters dedicated to downstream counting. Sim-ultaneous counting systems are characterized by reduced need for stable challenge aerosol concentration and by diffi-culty in correlating counters. super ULPA (ultralow-penetration air)
36、 filter A throwaway, extended-medium, dry-type filter in a rigid frame, made with filter medium having a minimum parti-cle collection efficiency of 99.9999% (i.e., a maximum particle penetration of 50, then nn 2 should be used. The correlation ratios should be calculated as: clclcuclucl UDR,cuclclcl
37、lcl UDR, 7.2 Penetration 7.2.1 Observed valuepenetration With the test filter installed, upstream and downstream counts should be obtained to calculate the observed penetration: ototoo RUDP, 7.2.2 UCL and LCL valuespenetration The UCL and LCL values should be calculated for the upstream and downstre
38、am counts, using Table A1 for numbers n 50, or using nn 2 for n 50. The UCL and LCL of the penetration should be calculated as: lcltlcltuclucl RUDP, IEST-RP-CC007.3 Institute of Environmental Sciences and Technology Copyrighted material 23 ucltucltlcllcl RUDP, 7.3 Retest (Section 6.7) If Pucl Pspec,
39、 the filter has passed. If Plcl Pspec, the filter has failed. If Plcl Pspec Pucl, a retest is permitted as described in section 6.7, or, if no retest is done, the filter has failed. 7.4 Calculations for unequal sample times If dtutdcuc TTTT then no adjustments for sampling time need to be made. If t
40、his condition is not met, then the equation for the observed penetration is: dtutdcuccocototoo TTTTUDUDP,The equations for the UCL and LCL values of the penetration are: dtdcucutcu c lcl c ltl c ltu c lu c l TTTTUDUDP,dtdcucutcl c lcu c ltu c ltl c ll c l TTTTUDUDP,7.5 Significant digits and roundin
41、g Calculated values of penetration should be rounded, using standard conventions, to two significant digits. When comparing the upper confidence limit on the filter penetration to the acceptance specification, it is not appropriate to round to fewer than two significant digits. Such rounding of digi
42、ts should not be understood to mean that the measurement is precise to two significant digits. The spread between the observed penetration and the 95% confidence levels on the penetration for repeated tests on reference filters provides estimates of the precision of the penetration measurement. 24 C
43、opyrighted material Institute of Environmental Sciences and Technology IEST-RP-CC007.3 7.6 Resistance (Appendix A, sections A4 and A16) Resistance of the filter should be corrected for air viscosity as a result of test air temperature that is different from the standard air temperature of 21 C (70 F
44、). The suggested correction factor formula is: where: Pc = filter resistance in Pa (in. w.c.), corrected to 21 C (70 F) Pm = filter resistance in Pa (in. w.c.), measured C1 = 1st constant, 0.9468 for C (0.902 for F) C2 = 2nd constant, 0.00252 for C (0.0014 for F) TT = test air temperature, C (F) 8 R
45、EPORTING AND MARKING a) Unless otherwise specified by contract, each filter unit should have a label with the following information: 1) manufacturer name or symbol 2) filter serial number, model number, and date 3) reference to this RP (e.g., “Tested per IEST-RP-CC007”) 4) test flow rate: actual vol
46、ume per unit time 5) penetration or efficiency a) 95% UCL penetration (or efficiency) for at least one particle size range in the span of 0.1 to 0.2 m, and b) observed penetration (or efficiency) for the same size range 6) particle size range, or MPPS for which the 95% UCL and observed penetrations
47、are reported 7) identification of MPPS in m 8) airflow resistance corrected as described in section 7.6 9) arrow showing direction of test airflow and identification of mounting surface during test (e.g., “Filter sealed to upstream face during test”) 10) test aerosol material In addition, penetratio
48、n data for other particle sizes that span the MPPS should be provided. b) Marking should be centrally located on the top of the filter frame with the pleats vertical or in other readily visible location on the frame. c) Where the size of the filter does not allow for sufficient label size, the infor
49、mation may be abbreviated or noted on more than one label. IEST-RP-CC007.3 Institute of Environmental Sciences and Technology Copyrighted material 25 APPENDIX AFACTORS INFLUENCING MEASURED PENETRATION A1 Particle size sphere equivalence A2 Mixing of aerosols A3 Airflow measurement A4 Viscosity and pressure drop A5 Poisson statistics and counting A6 Particle counter saturation and coincidence A7 Parti
