To establish a guideline for evaluating the removal efficiency by particle size and the resistance to airflow of an aircleaning device as installed in a field HVAC system. The guideline includes a separate procedure for evaluating particulate filtration system efficiency for systems that meet the defined criteria.<\/p>\n
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| 1<\/td>\n | ASHRAE Guideline 26-2012 \n <\/td>\n<\/tr>\n | ||||||
| 4<\/td>\n | Foreword Acknowledgment 1. Purpose 2. Scope <\/td>\n<\/tr>\n | ||||||
| 5<\/td>\n | 3. Definitions, Acronyms, and ABBREVIATIONS 3.1 Definitions 3.2 Acronyms and Initialisms 4. Test Equipment and Setup 4.1 Particle Counter. The particle counter should be capable of measuring particles in the size range 0.3 to 5.0 \u00b5m, in a minimum of four ranges, with a minimum of two ranges below 1.0 mm (e.g., 0.3\u20130.5, 0.5\u20131.0, 1.0\u20132.0, and 2.0\u20135.0 mm). Fo… 4.2 Diluter. A dilution system capable of diluting the aerosol concentration so the particle concentration level is within the acceptable concentration limits may be used. Choose a suitable dilution ratio so that the measured concentration of particl… 4.3 Pump. A pump may be used to control the rate of the sample flow qs through the sampling probes. A pump is not necessary when the counter flow qpc to the counter or diluter is sufficient for isokinetic sampling. In this case, the sample flow qs an… 4.4 Sampling System. Figure 4-1 shows the elements of a typical sampling system. <\/td>\n<\/tr>\n | ||||||
| 6<\/td>\n | Figure 4-1 Sampling system. Figure 4-2 Sample locations. <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | 4.5 Air Velocity Measurement Instrument. The instrument used to measure the air velocity should have sufficient operational limits such that the system airflow is within the limits of the instrument. The instrument should be chosen in accordance with… 4.6 Relative Humidity (RH) Measurement Instrument. The instrument used to measure the RH of the system airflow should be chosen in accordance with Chapter 36, \u201cMeasurement and Instruments,\u201d\u009d of the 2009 ASHRAE Handbook\u2014 Fundamentals.3 An instrum… Figure 4-3 Isoaxial sampling line to particle counter. 4.7 Temperature Measurement Instrument. The instrument used to measure the temperature of the system airflow should be chosen in accordance with Chapter 36, \u201cMeasurement and Instruments,\u201d\u009d of the 2009 ASHRAE Handbook\u2014 Fundamentals.3 An instrumen… 4.8 Resistance to Airflow Measurement Instrument. The instrument used to measure the resistance of the filter bank should have sufficient operational limits such that the filter bank resistance is within the limits of the instrument. The instrument s… 4.9 Test Equipment Maintenance and Calibration. Maintenance items and schedules should conform to Table 4-1, \u201cApparatus Maintenance Schedules.\u201d\u009d <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | TABLE 4-1 Apparatus Maintenance Schedules 5. Site Evaluation 5.1 Filter Installation Pretesting Inspection. Pre-inspection of filters and air-handling units is necessary to determine whether a filter installation is suitable for evaluation using this guideline. It is also used to gauge whether any potentially … 5.2 Approval for Testing. Once the pretesting inspection has been completed and the filter installation determined to be suitable for testing, then the \u201cApproval for Testing\u201d\u009d form should be completed and signed by representatives of the building … 6. Test Procedure 6.1 Air Velocity. Air velocity through the filter installation should be maintained constant for the duration of the test. This is possible if the fan speed is controllable through a variable-frequency drive (VFD) or variable air volume (VAV) boxes, … 6.2 Relative Humidity. The instrument(s) identified in Section 4.6, \u201cRelative Humidity (RH) Measurement Instrument,\u201d\u009d should be used for these measurements. It is recommended that the RH of the air passing through the filter installation be within… <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | 6.3 Temperature. The instrument(s) identified in Section 4.7, \u201cTemperature Measurement Instrument,\u201d\u009d should be used for this measurement. The temperature of the air passing through the filter installation should be within the operating range of th… 6.4 Resistance to Airflow. Resistance to airflow across the filter installation should be measured using the resistance to airflow instrument(s) identified in Section 4.8, \u201cResistance to Airflow Measurement Instrument.\u201d\u009d If existing pressure readi… 6.5 Removal Efficiency <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | Figure 6-1 Checking zero count at downstream sampling line. <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | 6.6 Sampling Probes <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 7. Expression of Results 7.1 General Information. A complete report shall include all the information in the \u201cFilter Installation Pretesting Inspection\u201d\u009d form and the \u201cApproval for Testing\u201d\u009d form (see Informative Appendices A and B). In addition, a completed test repor… 7.2 Data Collection. The data reported shall include the following: <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 8. Errors and Data Analyses 8.1 Relative Humidity (RH). High RH, typically above 80%, can cause variations in efficiency and can increase the resistance to airflow. High RH increases the size of hygroscopic particles. Particles may dry before reaching the detection chamber in t… 8.2 Air Temperature. Operating conditions at or below freezing will lead to freezing of permanently installed sampling probes and lines and to errors in particle counter operation if these conditions are outside the normal operating range, as well as… 8.3 Aerosol Composition. Since optical particle counters are the instrument of choice for many professionals in the field, the measured particle size is dependent on the refractive index and shape of the particles. However, one has little control ove… 8.4 Uniformity of Aerosol Concentration. The particle concentration in an installation typically varies with time and space. Such variations may lead to errors in the data. To minimize such errors, it is recommended that the system evaluation procedu… 8.5 Coincidence Errors\u2014Particle Counter. Coincidence errors in particle counters occur when two particles enter the viewing volume of the counter and their coincident signals are counted as one larger signal or particle. This is more common at high… 8.6 Particle Losses. Particle losses can occur in sampling lines in dilution systems, if used, and in instruments themselves. The losses are typically significant for larger particles due to impaction on surfaces, while very small particles minimize … 9. Calculation of Results 9.1 Calculation of Removal Efficiency. Each data set will consist of multiple samples. Data sets will be taken sequentially beginning and ending with a downstream data set and alternating between downstream and upstream as shown in Table 9-1. <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | TABLE 9-1 Sampling Cycle Example 9.2 Calculation of Uncertainty. The uncertainty on the average removal efficiency, as defined in Section 9.14, corresponds to a two-sided confidence interval of the average value based on a 95% confidence level. Uncertainty values should also be calc… 9.3 Coefficient of Variation (CV). The coefficient of variation is the standard deviation of a group of measurements divided by the mean. A CV value below 25% is generally acceptable for most measured values, except where noted. <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | TABLE 9-2 t Distribution Variable 10. Optional Enhanced Test System 10.1 Application of Enhanced Test. The purpose of the optional enhanced test system is to offer a method of correlation between standard laboratory test data and in-situ test data. By challenging a filter that has been previously tested under laborat… 10.2 Principle of the Enhanced Test System. Using the enhanced test system illustrated in Figure 10-1, it is possible to measure almost simultaneously the efficiency of the filter installation and a reference filter. The effects of varying measuremen… <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | TABLE 10-1 Sampling Cycles in the Enhanced Test System Figure 10-1 Schematic of the enhanced test system. Figure 10-2 Determination of the corrected particle size. 10.3 Determination of the Corrected Particle Size. An optical particle counter sizes the particles based on their optical properties. During in-situ measurement conditions, the optical properties of the particles may differ from the optical propertie… <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 10.4 Presentation of Results. When the enhanced test system is used, the test report should present the following data in addition to what is stated in Section 7, \u201cExpression of Results\u201d\u009d: 11. References <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | INFORMATIVE Appendix A Filter Installation Pretesting Inspection Form TABLE A-1 Air-Handling Unit TABLE A-2 Local Instrumentation TABLE A-3 Filter\/Frames <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | TABLE A-4 Utilities Filter Installation Pretesting Inspection Form\u2014Notes <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | INFORMATIVE Appendix B \u201cApproval for Testing\u201d\u009d Form Table B-1 Approval for Testing Form Table B-2 Approval for Testing Form\u2014Air-Handling Units to Be Tested <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | INFORMATIVE Appendix C Example of How to Complete Testing C1. Preliminary Forms C1.1 Filter Installation Pre-Testing Inspection Form Table C-1 Filter Installation Pretesting Inspection Form <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | C1.2 Approval for Testing Form Table C-2 Approval for Testing Form TABLE C-3 Air-Handling Units to Be Tested Figure C-1 Schematic drawing of the installation. C2. Qualification Testing C2.1 Velocity Data. Velocity readings are taken on the downstream side of each filter, maintaining the probe approximately 203 to 305 mm (8 to 12 in.) from each filter. Care is taken not to allow turbulence from personnel to influence the values. <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | TABLE C-4 Velocity Data Set #1 (Before Any Testing) TABLE C-5 Velocity Data Set #2 (After Testing) <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | C2.2 Isokinetic Sampling. Calculate the sample flow (qs) based on the measured average velocity. Sample probe diameter is 13 mm (0.51in): C2.3 Temperature and RH. Temperature and RH are measured by placing the probe into the airflow and collecting sufficient data points to record the average temperature and RH. C2.4 Resistance to Airflow Data. Resistance to airflow can be measured while the removal efficiency data is being measured. Since the installed gauge cannot be accurately read (0\u201310 Pa, 0\u201325 in. wg), the contractor will have to use his or her ins… C2.5 Particle Counter Zero Test. Install a HEPA filter to the particle counter air inlet for a minimum of a one-minute count measurement. If the calculated concentration is lower than the maximum, the test passes. C2.6 Upstream Particle Concentrations TABLE C-6 Temperature and Relative Humidity\u2014Average of 25 Readings TABLE C-7 Particle Counter Zero Test\u2014Total Counts in One Minute TABLE C-8 Prescreening of Particle Concentration\u2014Variations with Location <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | C2.7 System Zero Test. Install a HEPA filter at the downstream probe location air inlet for a minimum of a one-minute count measurement. If the measured particle concentration is less than 0.05% of the upstream concentration from Section C2.6, then t… C3. Filter Efficiency Data TABLE C-9 Prescreening of Particle Concentration\u2014Variations with Time TABLE C-10 Minimum Upstream Concentration Data <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | TABLE C-11 Particle Concentration Limit\u2014Upstream Concentration Data TABLE C-12 System Zero Test\u2014Total Counts in One Minute TABLE C-13 Downstream Data Sample Data Set TABLE C-14 Upstream Data Sample Data Set <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | TABLE C-15 Particle Count Data TABLE C-16 Filter Efficiency Calculation C3.1 Downstream Data. The downstream probe was located 305 mm (12 in.) from the back of the test filter at the center of the filter. C3.2 Upstream Data. The upstream probe was located 450 mm (18 in.) from the face of the test filter at the center of the filter. C3.3 Particle Count Data. The data sets were collected by alternating between downstream and upstream until all data sets were collected. The average particle counts for each particle size channel are shown. C3.4 Filter Efficiency Calculation. Efficiency values should not be reported for the channels that do not meet the data requirements. <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | C4. Sample Report Guideline 26 Test Report TABLE C-4 and C-5 Data (Velocity Data Sets Nos. 1 and 2) <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | TABLE C-6 Data TABLE C-7 Data Particle Counter Zero Test (Total Counts in One Minute) TABLE C-8 Data Pre-Screening of Particle Concentration\u2014Variations with Location TABLE C-9 Data Pre-Screening of Particle Concentration\u2014Variations with Time <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | TABLE C-10 Data Minimum Upstream Concentration Data TABLE C-11 Data Particle Concentration Limit\u2014Upstream Concentration Data TABLE C-12 Data System Zero Test\u2014Total Counts in One Minute TABLE C-13 Data Filter Efficiency Data\u2014Downstream Data Set D1 <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | TABLE C-14 Data Filter Efficiency Data\u2014Upstream Data Set U1 TABLE C-15 Data Particle Count Data TABLE C-16 Calculations (Filter Efficiency Calculation) <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Appendix D Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" ASHRAE Guideline 26-2012 Guideline for Field Testing of General Ventilation Filtration Devices and Systems for Removal Efficiency In-Situ by Particle Size and<\/b><\/p>\n |