1、Institute of Environmental Sciences and Technology IEST-RP-CC021.4 Contamination Control Division Recommended Practice 021.4 Testing HEPA and ULPA Filter Media Arlington Place One 2340 S. Arlington Heights Road, Suite 620 Arlington Heights, IL 60005-4510 Phone: (847) 981-0100 Fax: (847) 981-4130 E-m
2、ail: informationiest.org Web: www.iest.org 2 IEST 2016 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC021.4 This Recommended Practice was prepared by and is under the jurisdiction of Working Group 21 of the IEST Con-tamination Control Division (WG-CC021). The follow
3、ing WG voting members contributed to the development of this edition of this Recommended Practice: Donna Kasper, WG-CC021 Chair, Hollingsworth b) Test aerosol and particle size; c) Test face velocity. 1.2 Limitations This RP does not include discussion of special applications testing, such as nuclea
4、r, biological, chemical, and other such testing. Although the general approach to testing media outlined in this RP may be used for testing media with lower efficiencies than HEPA media, the user is cautioned that specific recommendations noted on aerosols, statis-tics, instrumentation, and other fa
5、ctors may not be appropriate. NOTE: Testing in accordance with this RP may involve hazardous materials, operations, and equipment. This RP does not purport to address all of the safety problems associated with its use. It is the responsibility of the user to establish appropriate safety and health p
6、ractices and to determine the applicability of regulatory limitations prior to use. 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 Reference documents ASTM F778-88 2007: Standard Me
7、thods for Gas Flow Resistance Testing of Filtration Media IEST-RP-CC001: HEPA and ULPA Filters IEST-RP-CC007: Testing ULPA Filters IEST-RP-CC013: Calibration Procedures and Guidelines for Select Equipment Used in Testing Cleanrooms and Other Controlled Environments 6 IEST 2016 All rights reserved In
8、stitute of Environmental Sciences and Technology IEST-RP-CC021.4 IEST-RP-CC014: Calibration and Characterization of Optical Airborne Particle Counters MIL-STD-282: Filter units, Protective Clothing, Gas-mask Components and Related Products: Performance Test Methods NIOSH 42 CFR Part 84 Respiratory P
9、rotective Devices. NIOSH Manual of Analytical Methods Procedure 500. TAPPI-T211: Ash in Wood, Pulp, Paper and Paperboard TAPPI-T410: Grammage of Paper and Paperboard TAPPI-T411: Thickness (Caliper) of Paper, Paperboard, and Combined Board TAPPI-T413: Ash in Wood, Pulp, Paper, and Paperboard: Combust
10、ion at 900 Degrees C TAPPI-T494: Tensile Breaking Properties of Paper and Paperboard (Using Constant Rate of Elongation Apparatus) TAPPI-T543: Bending Resistance of Paper (Gurley- Type Tester) 2.2 Sources and Addresses ASTM American Society for Testing and Materials 100 Barr Harbor Drive West Consho
11、hocken, PA 19428-2959, USA Phone: 610-832-9585 Fax: 610-832-9555 www.astm.org IEST Institute of Environmental Services and Technology Arlington Place One 2340 South Arlington Heights Road, Suite 620 Arlington Heights, IL 60005-4510 Phone: 847-981-0100 Fax: 847-981-4130 www.iest.org MIL-STD Standardi
12、zation Document Order Desk 700 Robbins Avenue Building 4, Section D Philadelphia, PA 19111-5094, USA http:/quicksearch.dla.mil/NIST National Institute of Standards and Technology 100 Bureau Drive Gaithersburg, MD 20899-1500, USA Phone: 301-975-4040 Fax: 301-926-1559 www.nist.gov NIOSH National Insti
13、tute for Occupational Safety and Health Centers for Disease Control and Prevention 1600 Clifton Rd. Atlanta, GA 30333, USA 800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 www.cdc.gov/niosh IEST-RP-CC021.4 Institute of Environmental Sciences and Technology IEST 2016 All rights reserved 7 TAPPI Techni
14、cal Association of Pulp and Paper Industry TAPPI Press P.O. Box 102556 Atlanta, Georgia 30368-0556, USA Phone: 404-446-1400 www.tappi.org 3 TERMS AND DEFINITIONS aerosol A gaseous suspension of fine solid or liquid particles. aerosol source material Aerosols used for testing HEPA or ULPA filter medi
15、a produced from a specified liquid having known properties. One commonly used aerosol source material is dioctyl phthalate (DOP), also known as di(2-ethylhexyl) phthalate (DEHP). airflow rate The airflow rate expressed as volumetric flow per unit of time. air resistance The loss of pressure caused b
16、y gas moving through the filter medium. basis weight The mass of a specified area of filter medium; also referred to as grammage. challenge aerosol An aerosol derived from the selected aerosol source material and used as the leak-test challenge for a filter leak test. Challenge aerosols may be produ
17、ced 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 upstream counts with no filter in the test system (see Appendix B1). For sequential counting systems, the correlation ratio represent
18、s 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 systems, the correlation ratio represents the same factors as for sequential counting sys-tems, as well as the difference
19、s between the different particle counting instruments used upstream and downstream, such as: sample flow rate counting efficiency count or number median diameter of aerosol (CMD) The 50th percentile of the number distribution of the aerosol; i.e., 50% of the particles are smaller than the count medi
20、-an diameter and 50% are larger than the count median diameter. DOP or DEHP Dioctyl phthalate (DOP) or di(2-ethylhexyl) phthalate (DEHP); CAS# 117-81-7. DOS or DEHS Dioctyl sebacate (DOS) or di(2-ethylhexyl) sebacate (DEHS); CAS# 122-62-3. filter medium A permeable material that separates solid part
21、icles or liquid droplets from a fluid passing through it. 8 IEST 2016 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC021.4 grammage See basis weight. HEPA (high-efficiency particulate air) filter An extended-medium, dry-type filter in a rigid frame having a minimum
22、particle collection efficiency of 99.97% for 0.3-m mass median diameter particles of DOP when tested at the rated airflow in accordance with MIL-STD-282. NOTE: The foregoing is the traditional definition for the HEPA filter. Changes in filter manufacture, end user re-quirements, and testing have int
23、roduced 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. laminar flow Streamline flow in a fluid (such as air) near a solid boundary (such as a duct wall), characterized by
24、an upper-limit Reynolds number. Laskin nozzle A nozzle used as part of a system to generate a heterogeneous aerosol from a liquid, such as PAO, DOP, or other oil, that uses a source of compressed gas as shown in IEST-RP-CC013. Laskin-nozzle-generated aerosol An aerosol generated by a Laskin nozzle f
25、rom PAO, DOP, or other oil. mass median diameter of aerosol (MMD) The 50th percentile of the mass distribution of the aerosol; i.e., 50% of the mass of the aerosol is made up of particles smaller than the mass median diameter and 50% of the mass of the aerosol is made up of particles larger than the
26、 mass median diameter. 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 theory, the efficiency is higher for particle sizes sma
27、ller 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. particle concentration The number of particles detected per unit volume of air. particle size The apparent maxim
28、um linear dimension of a particle in the plane of observation, as observed with an optical micro-scope; or the equivalent diameter of a particle detected by automatic instrumentation. The equivalent diameter is the diameter of a reference sphere having known properties and producing the same respons
29、e in the sensing instrument as the particle being measured. Current particle size range of interest can vary upward from sizes smaller than 0.1 m. PAO (4 cSt poly-alpha-olefin) A grade of PAO with a viscosity of 4 centistokes at 100 C. With reference to filter testing, PAO also refers to a poly disp
30、erse aerosol of the described material. penetration The ratio of the number of particles exiting the filter to the number of particles entering the filter, per unit time, ex-pressed as a percentage for a stated particle size range (see Appendix B, sections B5 and B6). It can also be the ratio of mas
31、s of the aerosol challenge measured with photometry. 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 were repeated indefinitely. UCL and LCL penetration The 95% upper c
32、onfidence limit (UCL) penetration and 95% lower confidence limit (LCL) penetration are values statistically calculated from the observed counts. There is a 95% confidence that the true mean pene-tration is between the UCL and LCL penetrations. IEST-RP-CC021.4 Institute of Environmental Sciences and
33、Technology IEST 2016 All rights reserved 9 percent elongation The percent increase in the dimension of the material in the direction of stress at the point of failure. sequential counting system A system that uses a single detector to determine the concentrations of the test aerosol, both upstream a
34、nd downstream of the filter medium, by alternating the sampling locations of the detector. simultaneous counting system A system that uses a pair of detectors to determine simultaneously the concentrations of the test aerosol upstream and downstream of the filter medium. stiffness Resistance to bend
35、ing when flexural stress is applied. tensile strength The maximum stress a material can withstand when subjected to stretching. thermally generated aerosol An aerosol generated by quenching (condensing) vapor that has been evaporated from oils such as DOP or PAO by heat. thickness The dimension perp
36、endicular to the plane of the filter medium. ULPA (ultra-low-penetration air) filter A throwaway, extended-medium, dry-type filter in a rigid frame, having a minimum particle-collection efficiency of 99.999% (that is, a maximum particle penetration of 0.0010%) when tested in accordance with the meth
37、ods of IEST-RP-CC007. ULPA filters are defined and described in IEST-RP-CC001. water repellency The ability of a filter medium to resist wetting. 4 TEST METHODS 4.1 Test for resistance to airflow Resistance to airflow should be tested according to ASTM-F778, observing the exceptions noted in section
38、 4.1.3 of this RP. 4.1.1 Resistance to airflow test description This test method describes a procedure for measuring airflow resistance (pressure drop) across a sample of known geometry at one or more airflow rates. It is recommended that airflow for testing air resistance of HEPA and ULPA media be
39、laminar. 4.1.2 Resistance to airflow test equipment a) Medium holding device, or chuck (Figure 1, item 4) The medium holding device should be a cylinder of simple construction, preferably a pneumatically actuated top clamp with low-surface-area sealing. All materials used in the medium test system t
40、hat contact the test airstream, including sampling lines, should be cleanable, corrosion-resistant, electrically conductive and grounded, and should shed minimal particles. The pre-ferred materials are polished stainless steel and anodized aluminum. The velocity profile across the face of the medium
41、 should be 10%. There should be no recirculation zones or uncir-culated areas that trap particles in the chuck flow path. The recommended test area is 100 cm2 (15.5 in2). If a support grid is used, the effect of the support grid on the measured sample pressure drop should be less than 1%. 10 IEST 20
42、16 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC021.4 The medium holding device should be leak-free. Any gaskets used for securing the sample should not damage the sample. This may require extra care when testing delicate materials such as ePTFE or nano fiber filt
43、er media. b) Pressure drop taps Pressure drop should be measured with a differential pressure device that is connected to pressure taps on both up-stream and downstream sides of the test medium. Pressure taps should be of the static-pressure rather than the total-pressure type, and mounted at right
44、angles to the airflow to minimize velocity effects on the measurements. It is recommended that the taps be located a distance of at least one diameter of the test medium away from the me-dium to minimize turbulence effects resulting from changes in the cross section of the test duct. c) Manometer or
45、 suitable pressure transducer Typical tolerance is 2% of full scale (span). d) Tare Tare, which is the test fixture resistance without the test media in place, should be measured at the sample flow rate and subtracted from the media test results. 4.1.3 Resistance to airflow test procedure The test s
46、hould be conducted according to ASTM-F778, with the following exceptions: The area of the test sample should be known to within 2%. The face velocity should be 5.33 cm/sec (10.5 ft/min) unless otherwise agreed upon by the customer and the supplier. 4.1.4 Data reporting for resistance to airflow test
47、 Pressure drop measurement should be reported in millimeters of water column. 4.1.5 Equipment qualification and calibration for resistance to airflow test Calibration should be performed according to ASTM-F778. See Appendix A for calibration frequency. 4.2 HEPA and ULPA filter media penetration test
48、 Penetration of HEPA and ULPA filter media can be determined with the use of various test instrumentations. Both photometric and particle count (see Appendix B4) techniques and particles smaller than 0.1 m are capable of providing valid penetration measurement data for HEPA and ULPA filter media. To
49、 present comparable data, it is recommended that both the penetration test data and the test technique be stated, in addition to the correlated value of the penetration as determined by photometric method. More information is avail-able in ASTM-D2986 and MIL-STD-282 (see Appendix D). 4.3 HEPA filter media penetration testphotometric method The following procedure presents the equipment, terms, aerosol, processes, and calculations used in determining the efficiency of HEPA filter media using photometry. The discussion provides guidelines for constructing
