1、 CONTENTSASHRAE Guideline 26-2012Guideline for Field Testing of General Ventilation Filtration Devices and Systems forRemoval Efficiency In-Situ by Particle Size and Resistance to AirflowSECTION PAGEForeword. 21 Purpose 22 Scope . 23 Definitions, Acronyms, and Abbreviations 34 Test Equipment and Set
2、up. 35 Site Evaluation 66 Test Procedure . 67 Expression of Results. 108 Errors and Data Analyses. 119 Calculation of Results. 1110 Optional Enhanced Test System 1311 References . 15Informative Appendix A: Filter Installation Pretesting Inspection Form 16Informative Appendix B: “Approval for Testing
3、” Form. 18Informative Appendix C: Example of How to Complete Testing. 19Informative Appendix D: Bibliography. 30NOTEApproved addenda, errata, or interpretations for this guideline can be downloaded free of charge from the ASHRAE Web site at www.ashrae.org/technology. 2012 ASHRAE1791 Tullie Circle NE
4、Atlanta, GA 30329www.ashrae.orgAll rights reserved. ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.2 ASHRAE Guideline 26-2012(This foreword is not part of
5、 this guideline. It is merelyinformative and does not contain recommendations orrequirements necessary for conformance to theguideline.)FOREWORDThe purpose of this guideline is to provide a test proce-dure for evaluating the in-situ performances of general venti-lation filtration devices and systems
6、. Although any filter withan ASHRAE Standard 52.2-2010 efficiency from MERV 1-16could theoretically be tested using this guideline, it may be dif-ficult to achieve statistically acceptable results for filters withperformance below a typical MERV 11 value.Supply air to the HVAC system contains viable
7、 and non-viable particles of a broad size range. Over time, these parti-cles will cause problems for fans, heat exchangers, and othersystem parts, decreasing their function and increasing energyconsumption and maintenance. For health issues, the fine par-ticles (1.0 m will therefore have lower accur
8、acy, so the resultsshould be interpreted with respect to this.Particles in the 0.3 to 5.0 m size range are typically mea-sured by particle counters that can determine the concentra-tion of particles in specific size ranges. These instruments arecommercially available and will determine particle size
9、 alongwith the concentration level by several techniques (e.g., lightscattering, electrical mobility separation, or aerodynamicdrag). Devices based on light scattering are currently the mostconvenient and commonly used instruments for this type ofmeasurement and are, therefore, the type of device us
10、ed withinthis guideline.During in-situ measurement conditions, the optical prop-erties of the particles may differ from the optical properties ofthe particles used for calibrating the particle counter and test-ing it in the laboratory. Thus, the particle counter could sizethe particles differently b
11、ut count the overall number of parti-cles correctly. By adding an extra reference filter, the effect of varyingmeasuring conditions can be reduced. Additionally, using thisenhanced test method, the results can be used to correct themeasured efficiencies in relation to the efficiency of the refer-enc
12、e filter measured in laboratory using a standardized testaerosol.The results from using the standard method or theenhanced method will give both users and manufacturers abetter knowledge of actual filter and installation properties.It is important to note that field measurements generallyresult in l
13、arger uncertainties in the results compared to labo-ratory measurements. Field measurements may produceuncertainty from temporal and spatial variability in particleconcentrations, from limitations on sampling locations due toair-handling unit configurations, and from the use of fieldinstrumentation.
14、 These factors may result in lower accuracyand precision in the calculated fractional efficiencies as com-pared to laboratory measurements. It is the intent of thisguideline to provide a practical method in which the accuracyand precision of the result are maximized (and the precision ofthe result q
15、uantified) by recommending appropriate samplinglocations, sample quantities, and instrumentation. This guide-line is not intended to serve as a filter performance ratingmethod.The guideline also describes performance specificationsfor the equipment and defines methods of calculating andreporting the
16、 results.This is a revision of ASHRAE Guideline 26-2008. Thisguideline was prepared under the auspices of ASHRAE. Itmay be used, in whole or in part, by an association or gov-ernment agency with due credit to ASHRAE. Adherence isstrictly on a voluntary basis and merely in the interests ofobtaining u
17、niform standards throughout the industry. The changes made for the 2012 revision were as follows: Updated referencesMinor editorial changesACKNOWLEDGMENTThe ASHRAE Guideline Project Committee would liketo thank Eurovent for allowing ASHRAE to build upon theexcellent work this organization published
18、with Eurovent 4/10-2005, In Situ Fractional Efficiency Determination ofGeneral Ventilation Filters (see Informative Appendix DBibliography). Without the help of Eurovent, this projectwould have been more difficult and time consuming tocomplete.1. PURPOSETo establish a guideline for evaluating the re
19、moval effi-ciency by particle size and the resistance to airflow of an air-cleaning device as installed in a field HVAC system. Theguideline includes a separate procedure for evaluating partic-ulate filtration system efficiency for systems that meet thedefined criteria.2. SCOPEThis guideline describ
20、es a procedure for measuring theperformance of general ventilation air-cleaning devices in anend-use installed configuration. The performance measure-ments include removal efficiency by particle size and the resis-tance to airflow. The procedures for test include the definitionand reporting of the s
21、ystem airflow.The procedure describes a method of counting ambientair particles of 0.3 to 5.0 m upstream and downstream of thein-place air cleaner(s) in a functioning air-handling system.The procedure describes the reduction of particle counter datato calculate removal efficiency by particle size. S
22、ince filter installations vary dramatically in design andshape, a protocol for assessing the suitability of a site withregard to filter and system evaluation is included. When the ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print o
23、r digital form is not permitted without ASHRAEs prior written permission.ASHRAE Guideline 26-2012 3evaluated site conditions meet the minimum criteria estab-lished for system evaluation, the performance evaluation ofthe system can also be performed according to this procedure.The procedure for testi
24、ng also describes performancespecifications for the testing equipment and defines proce-dures for calculating and reporting these results. This proce-dure is not intended for measuring performance of portable ormovable room air cleaners. This guideline is not intended forevaluation of HEPA and ULPA
25、filter installation(s).3. DEFINITIONS, ACRONYMS, AND ABBREVIATIONS3.1 Definitionsair filter bypass: unfiltered air that passes through the air-handling unit (AHU) filter installation but remains unfilteredbecause it bypasses the installed air filters.air velocity: the rate of air movement at the fil
26、ter expressed inm/s (fpm) to three significant figures.allowable measurable concentration of the particle counter:50% of the maximum accurately measurable concentration asstated by the manufacturer of the particle counter.coefficient of variation (CV): the standard deviation of agroup of measurement
27、s divided by the mean.diluter/dilution system: a system for reducing the sampledconcentration to avoid coincidence error in the particle counter.filter efficiency: the removal efficiency of a filter as deter-mined by this guideline, where upstream and downstreamparticle count measurements are taken
28、close to the filter beingtested. filter installation: filtration devices and systems, such as asingle filter or a group of filters mounted together, with thesame inlet and outlet of air. This definition covers both devicesand systems. general ventilation: the process of moving air into or about aspa
29、ce or removing it from the space. The source of ventilationair is either air from outside the space, recirculated air, or acombination of these.isoaxial sampling: sampling in which the flow in the samplerinlet is moving in the same direction as the flow beingsampled.isokinetic sampling: sampling in
30、which the flow in thesampler inlet is moving in the same direction and at the samevelocity as the flow being sampled.particle counter: an instrument, such as an optical particlecounter, that uses the technique of light scattering for deter-mination of particle count by size.particle size range: a de
31、fined particle counter channel.reference filter: a small dry media-type filter that has beenlaboratory tested for removal efficiency by particle sizeaccording to ASHRAE Standard 52.2-2010.1It can be used inSection 10, “Optional Enhanced Test System.”removal efficiency by particle size: for a given p
32、article-sizerange (particles between two diameter values), the removalefficiency is the ratio of the number of particles retained by thefilter to the number of particles fed upstream of the filter.resistance to airflow: the loss of static pressure caused by thefilter and filter loading. The pressure
33、 loss is measured with thefilter operating at the measured air velocity and expressed inPa (in. wg) to two significant figures.system efficiency: the removal efficiency of a filter systemwhere upstream and downstream particle count measurementsmay be across several filter banks or other system compo
34、nents.3.2 Acronyms and InitialismsAHU air-handling unitCV coefficient of variationHEPA high-efficiency particle airHVAC heating, ventilating, and air-conditioningMERV minimum-efficiency reporting valueOPC optical particle counterRH relative humidityULPA ultra low-penetration airVAV variable air volu
35、meVFD variable-frequency drive4. TEST EQUIPMENT AND SETUP4.1 Particle Counter. The particle counter should be capa-ble of measuring particles in the size range 0.3 to 5.0 m, in aminimum of four ranges, with a minimum of two ranges below1.0 m (e.g., 0.30.5, 0.51.0, 1.02.0, and 2.05.0 m). Formaintenan
36、ce and calibration of the particle counter, see Sec-tion 4.9, “Test Equipment Maintenance and Calibration.”4.2 Diluter. A dilution system capable of diluting the aero-sol concentration so the particle concentration level is withinthe acceptable concentration limits may be used. Choose asuitable dilu
37、tion ratio so that the measured concentration ofparticles is well within the allowable measurable concentra-tion limits of the particle counter in order to achieve good sta-tistical data (see Section 9.1.2, “Minimum UpstreamConcentration”). If a dilution system is used, it is to be usedfor both upst
38、ream and downstream sampling. The dilutionsystem shall not change airflow to the particle counter.4.3 Pump. A pump may be used to control the rate of thesample flow qsthrough the sampling probes. A pump is notnecessary when the counter flow qpcto the counter or diluteris sufficient for isokinetic sa
39、mpling. In this case, the sampleflow qsand the counter flow qpcare the same.4.4 Sampling System. Figure 4-1 shows the elements of atypical sampling system.4.4.1 Sampling Probes. The sampling probe should consistof a sharp-edged nozzle connected to the sample line leading tothe auxiliary pump or part
40、icle counter. The diameter of the noz-zle is dependent on the sample flow qsin order to get isokineticsampling. The diameter should not be less than 8 mm (0.31 in.).4.4.2 Sampling Lines. Sampling lines upstream anddownstream should be of equal length and as short as possible ASHRAE (www.ashrae.org).
41、 For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.4 ASHRAE Guideline 26-2012Figure 4-1 Sampling system.Figure 4-2 Sample locations. ASHRAE (www.ashrae.org). For personal use only. A
42、dditional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.ASHRAE Guideline 26-2012 5to avoid losses. Material should preferably be of a type withminimum particle losses for filter installations. Software isavailabl
43、e to calculate line losses.24.4.3 Sampling Locations. Sampling locations should beplaced close to the filter, as shown in Figure 4-2. If the systemefficiency is to be tested, the sampling locations should be fur-ther away to achieve good mixing of airflow through filters,frames, doors, etc. A measur
44、ement of system efficiency ismore difficult; therefore, it is a good practice to plan the mea-surement carefully and describe in detail how it was made. 4.4.4 Valve (Manual or Automatic). A valve may beused to switch between upstream and downstream samplelocations. The valve should be constructed so
45、 that particlelosses are identical in upstream and downstream measure-ments. No influence on efficiency due to the valve construc-tion is permitted (e.g., four-point ball valves of sufficientdiameter may be used).4.4.5 Isoaxial Sampling Nozzle. If a pump (Section 4.3,“Pump”) is used to obtain isokin
46、etic sampling, the sampleline should then be fitted with an isoaxial sampling nozzledirectly connected to the particle counter or diluter, as shownin Figure 4-3.4.4.6 Flowmeter. A flowmeter is necessary if a pump ispart of the sampling system. The flowmeter should be locatedin line with the pump inl
47、et or outlet.4.5 Air Velocity Measurement Instrument. The instru-ment used to measure the air velocity should have sufficientoperational limits such that the system airflow is within thelimits of the instrument. The instrument should be chosen inaccordance with Chapter 36, “Measurement and Instrumen
48、ts,”of the 2009 ASHRAE HandbookFundamentals.3An instru-ment that records data values and will average those values isrecommended. Ideally, the instrument should have the abilityto correct measurements to standard sea-level conditions.4.6 Relative Humidity (RH) Measurement Instrument.The instrument u
49、sed to measure the RH of the system airflowshould be chosen in accordance with Chapter 36, “Measure-ment and Instruments,” of the 2009 ASHRAE HandbookFundamentals.3An instrument that records data values andwill average those values over time is recommended.4.7 Temperature Measurement Instrument. The instru-ment used to measure the temperature of the system airflowshould be chosen in accordance with Chapter 36, “Measure-ment and Instruments,” of the 2009 ASHRAE HandbookFundamentals.3 An inst
