G U National Air Filtration Association Recommended Practice I D E L I N E Procurement Guideline TRAINING EDUCATION CERTIFICATION
HVAC Air Filter Purchasing Specification Guideline 1.0 Purpose To provide air cleanliness to the Heating, Ventilation, and Air-Conditioning, (HVAC) Systems - HVAC system components, i.e. coils, ductwork, and clean air to the occupied space. 2.0 Scope This suggested specification covers the air filtration products that are a component of the HVAC system. 3.0 Construction 3.1 The filter shall have the size of filter with air flow directional arrow labeled on the enclosing frame. Filters shall be rated UL Std. 900 Class 1 or Class 2 and shall be listed on the frame. 3.2 Filters shall be constructed as specified by type: Panel Filter Pleated Filter Cell-style Filter Pocket Filter Rigid Box Filter Mini-pleat V-Cell Filter 3.3 Filter media shall be manufactured as specified by type; Spun Fiberglass Meltblown Synthetic Wet-laid Microfiberglass Lofted Synthetic Lofted Fiberglass Mixed nano-fiber media 4.0 Performance 4.1 Filters shall be a (Minimum Efficiency Reporting Value), MERV @ fpm 4.2 Filters shall have an initial airflow pressure drop of w.g. @ fpm 4.4 The MERV performance data shall be based on ANSI/ASHRAE Standard 52.2-2007 5.0 Documentation 5.1 An independent laboratory ANSI/ASHRAE Std. 52.2-2007 test report shall be submitted for each type of filter. 5.2 Filter Model No. on test report shall match that of each type of product tested. 5.3 A sample of each filter shall be submitted for engineering evaluation and approval.
NAFA Procurement Guideline (This expanded explanation is provided to those who need clarification on required items listed on the Purchasing Specification Guideline. ) Purpose This guideline is designed to assist the procurement specialist in selecting and evaluating filters for their filter bids. Information is also provided to explain air filter tests and how test reports should be used to ensure filters supplied by vendors are comparable and meet user specifications. Background Over recent years with the changes in filter testing and evaluation many end users are faced trying to evaluate the same type of filter with different types of test data and different test reports. This confusion makes choosing the best filter which meets the specifications required very difficult. This document is intended to provide the most up-to-date information on currently approved filter test standards. NAFA Guidelines NAFA recommends that the procurement agent request a copy of ASHRAE standard 52.2, the most recent approved ASHRAE test method for air filters. The tests for filters under ASHRAE 52.1 are no longer in effect and the Standard was retired as of January, 2007. The test should be from an independent laboratory and it should be representative of the filter you are purchasing. If the specifications call for a HEPA filter, one should request test data done with a suitable challenge agent that will demonstrate filter efficiency of not less than 99.97% on 0.3 micrometer particles at rated airflow. This test information should be clearly labeled on the filter when supplied to ensure that the filter you are using meets the specification. Maintenance The procurement agent should ensure that no changes are made to the filter being supplied versus the one for which the report was issued. If this happens, a new test should be requested. From time to time ASHRAE will update their filter test methods. When this happens NAFA will update this guideline. Please contact your local NAFA Certified Air Filter Specialist (CAFS) for information on the most recent test method. Air Filter Parameters Air filters should be compared on 3 characteristics: (a) particle efficiency (removal efficiency); (b) pressure drop (resistance to the flow of air through the media); and (c) contaminant holding capacity (amount of media in the filter to capture and hold contaminants before reaching its final terminal pressure). Air Filter Test Standard For Efficiency The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is a worldwide not-for-profit society of heating, ventilating air conditioning and refrigeration (HVAC&R) engineers. ASHRAE provides research into all aspects of HVAC&R to the betterment of humankind. ASHRAE does not provide air filter ratings or testing facilities. They do not manufacture air filters nor do they profit from testing. In 1989, ASHRAE funded a research project that resulted in a method of test (MOT) for general ventilation filters. The MOT in its most recent form is called, ANSI/ASHRAE Standard 52.2-2007, Method of Testing General Ventilation Air- Cleaning Devices for Removal Efficiency by Particle Size. The MOT is available for purchase from ASHRAE at www.ashrae.org
In summary, the MOT provides end-users with a test that shows an air filters efficiency on specific particle size ranges E1, E2, and E3 and has designated efficiency shown by a single number called a minimum efficiency reporting value (MERV). E1 E1 is the smallest particle size range in the ASHRAE 52.2 test and is comprised of particles 0.3 micrometer to 1.0 micrometer in diameter. This size range of particles is considered by most authorities and backed by extensive research to be the most easily respirable particle sizes and are susceptible to being inhaled deeply into the human lung. Filters that are MERV 13 to MERV 16 are required to remove a substantial number of particles in this range. E2 E2 is the second size range of particles and represent those in the range of 1.0 micrometers to 3.0 micrometers in diameter. This range represents a category of particles that may be inhaled into the upper and lower respiratory system. Filters from MERV 9 to MERV 16 are required to remove a substantial number of particles in this range. E3 E3 is the third particle size range from 3.0 micrometers to 10.0 micrometer particles. Filters that substantially remove this size particle are MERV 6 through 16. A copy of the MERV table and particle removal efficiencies is made part of this Guideline. Independent Laboratory Testing of Air Filters In order to achieve non-bias in an air filter testing report, all reports used for comparison purposes should be reports done by an independent testing laboratory. Factory tests reports should not be used for any purpose other than on promotional company literature and even these test results should be done by an independent laboratory. For a list of laboratories that do air filter testing, go to the NAFA website at www.nafahq.org Pressure Drop All filters add resistance to the flow of air in a system. In most all instances, the higher the MERV number, the higher the resistance to the flow called pressure drop across the filter. As filters load with contaminants the resistance to flow increases to a manufacturer recommended final pressure. This pressure is measured by a device called a manometer and measures in inches of water (iw) called water gauge (wg). As the pressure increases the flow of air in the system decreases causing the system to run longer to satisfy the thermal conditions called for by the thermostat, resulting in excess energy consumption, usually beyond the initial cost of a new filter. Operating a filter beyond its terminal pressure can also cause it to collapse in the system or restrict the flow of air to the point where damage is caused to the system components. In other words, always use a gauge to determine the pressure in the system and don t run a filter past its terminal pressure. Contaminant Holding Capacity or Comparison of Filters with the Same MERV Number One more factor in air filter performance is filter life in service. In other words, how long will the filter be able to stay in the system before it reaches its design end-of-life pressure? The amount of media in an air filter usually determines contaminant load (how much it can hold). Filters with more media tend to last longer in the system and be a better filter because they require fewer changes hence less labor and greater life cycle cost savings. Two filters with exactly the same MERV number may have different contaminant holding capacity because one might have less media than the other. Procurement Specialist may have difficulty with comparison because of the amount of media differential since both have the same
MERV particle removal efficiency number. However, this can be overcome by dividing the amount of media in the filter by the initial cost to determine the cost per square foot of media in the filter so that a side-by-side comparison of same MERV number filters will yield equality. Example: Filter A is a MERV 6 filter with pleated filter with 12 square foot of media in the frame. Filter B is a pleated filter with 18 square foot of media in the frame. If filter a costs $4.50 and filter B costs $5.50, the cost per square foot of Filter A would be $0.37.5 sq. ft. and Filter B would be $0.30.5 sq. ft. Filter B should last approximately 25% longer in service, may have a lower pressure drop in the clean configuration and will provide the greater value even though the initial cost is higher. This is a generalized example and pricing and media type and content varies with each manufacturer. Consult your CAFS for specifications and pricing of a specific filter. High Efficiency Particulate Air (HEPA) Filters High Efficiency Particulate Air (HEPA) filters are those filters with a minimum efficiency of 99.97% on 0.3 micrometer particles. HEPA filters were originally designed to remove nuclear radiation particles from laboratory air during the Manhattan Project. Post-war applications include providing particle-free air to hospital isolation rooms and operating suites, biological safety cabinets and laminar flow hoods, cleanrooms, and contaminant of hazardous particles from manufacturing processes and microbiological research facilities. HEPA filters are tested utilizing a challenge that is a monodispersed known particle size challenge of Dioctylphthalate (DOP) or other acceptable challenge. Upstream concentrations are compared to downstream concentrations and particle penetration through the filter is converted to removal efficiency. HEPA filters also come in higher removal efficiencies including Ultra Low Penetration Air (ULPA) filters 99.999% efficiency and Super Ultra Low Penetration Air (SULPA) filters 99.9999% efficiency. Since the invention of the real-time particle counter, other sizes of particles are now used to determine efficiency due to the discovery that airflow velocity through a filter changes the particle removal characteristics. The term most penetrating particle size (MPPS) applies to this principle and is now used to determine efficiency. Because all HEPA filters involve a degree protection that has been specifically designed and often required to achieve a level of air cleanliness, the Procurement Specialist should not deviate from the specified HEPA filter in the system without first consulting a NAFA CAFS or a specifying mechanical engineer. One final Note The initial purchase price of a filter does not represent its true cost. Life cycle costing of air filter products helps to determine overall cost throughout the life of the filter. Factors such as initial cost, freight in, storage and warehouse costs, slippage, installation and labor costs, electrical consumption and disposal costs should be factored into the equation. NAFA provides a no-cost Excel spreadsheet format for this purpose. Contact www.nafahq.org to obtain your copy of this spreadsheet. Automatic Updates If you would like to receive automatic updates to Standards and Guidelines as they occur, please contact NAFA at nafa@nafahq.org to request this service. Input and Feedback User input and feedback on NAFA documents is always welcomed and can be sent to NAFA at nafa@nafahq.org
Other Publications of Interest on Air Filtration The NAFA Guide to Air Filtration and the Installation, Operation and Maintenance of Air Filtration Systems are two publications that provide additional information about all aspects of air filtration. Both texts are the basis for NAFA accreditation of personnel including: Certified Air Filter Specialist (CAFS); NAFA Certified Technician (NCT). Both the CAFS and NCT require extensive study, passing a written national examination, and ongoing continuing education credits in order to maintain the accreditation. Glossary ASHRAE: American Society of Heating, Refrigerating, and Air Conditioning Engineers NAFA: National Air Filtration Association CAFS: Certified Air Filter Specialist HEPA/ULPA/SULPA: High Efficiency Particulate Air filters of increasing particle size efficiency DOP: Dioctylphthalate or similar challenge aerosol Include: 52.2 MERV Parameter Chart Revised June, 2010.
Other NAFA Publications NAFA Guide to Air Filtration NAFA Guide to Air Filtration Air filtration is one of the most important considerations involving the design, installation and maintenance of HVAC systems, yet is one of the least understood concepts in the HVAC industry. Thus, the need for the NAFA Guide to Air Filtration, which is the most informative and comprehensive manual ever published in the HVAC Industry. Now in its 3rd edition, the NAFA Guide to Air Filtration covers principles of air filtration, applications of all types of air filter products, filter testing methods, indoor air quality, filter owning and operating costs, plus much, much more. Over 200 pages with numerous tables, photos and illustrations help to educate the reader on the mechanics and elements of air filtration. The NAFA Guide to Air Filtration is required reading for anyone wishing to become a NAFA Certified Air Filter Specialist. The certification examination is based on material in the manual. It is also suggested reading for anyone involved in the design, installation, or maintenance of HVAC systems. For a copy of the NAFA Guide to Air Filtration, contact a NAFA member in your area or the NAFA home office. Installation, Operation & Maintenance of Air Filtration Systems Member Cost: $49.00; Nonmember Cost: $79.00 Installation, Operation & Maintenance of Air Filtration Systems This manual is designed to serve as a guide for those involved in the installation, operation, and maintenance (IOM) of air filtration systems. Over 100 pages with nearly 50 illustrations highlight the universal characteristics and the important procedures involved in the IOM of air filtration systems. Ideal for both teaching the basics to individuals just starting out in the field, as well as serving as a reference guide for experienced personnel, this manual is a must for anyone involved in the industry. The NAFA IOM Manual is required reading for the NAFA Certified Technician (NCT) program. Member Cost: $35.00; Nonmember Cost: $45.00
NAFA Programs NAFA Certified Air Filter Specialist Program The CAFS program distinguishes those professionals who have demonstrated a thorough, up-to-date understanding of air filtration technology and a high level of professionalism. In order to become certified, air filtration professionals must pass an extensive examination on the principles, methods and applications of air filtration, based on the text, NAFA Guide to Air Filtration, 3 rd Ed. Candidates for certification are also subject to compliance with the NAFA Code of Ethics. Certification is renewable on an annual basis pending successful completion of continued education requirements in order to demonstrate current and continued expertise. When purchasing products or services from a Certified Air Filter Specialist, customers are assured that their particular requirements and needs will be addressed by a knowledgeable professional. NAFA Certified Technician Program The NAFA Certified Technician Program (NCT) is a certification program for technicians involved in the installation, operation, and maintenance of commercial air filtration systems. Originally created for NAFA members, the program has been redesigned to suit the needs of facility managers, building owners, HVAC service contractors, and those who employ technicians in the HVAC industry. In order to certify technicians, candidates must pass an exam administered by any NAFA Certified Air Filtration Specialist (CAFS). Training sessions with a CAFS, self-study, and seminars, prepare candidates for the exam, which is an open book test with NAFA s Installation, Operation, and Maintenance of Air Filtration Systems Manual (IOM Manual). Being NAFA certified provides education for individuals in the service of air filtration systems, recognizes the knowledge and expertise of technicians, and develops formalized structure for ongoing education of maintenance staff. NAFA Product Certification One of NAFA s latest initiatives is the development of the NAFA Product Certification Program. The program is designed to verify the performance of various air filter products as advertised by their manufacturers. Participation by manufacturers in the program is voluntary. As the program gets underway, it is expected that most major manufacturers will submit products for certification. The public may access the NAFA website to see which products have been certified through the program.