HEPA filter is mainly used to capture particles and various suspended matters above 0.5μm. It usually adopts ultra-fine glass fiber as filter material, offset paper, aluminum film and other materials as dividing plate, and glued with wooden frame aluminum alloy. With the development of new materials and technologies, HEPA filter has gradually evolved from mainly using glass fiber as filter media to using new materials such as PTFE, nano-film materials and composite materials.
High efficiency filter has high filtration efficiency, low resistance, large dust holding capacity and other characteristics, can be widely used in optical electronics, LCD liquid crystal manufacturing, biological medicine, precision instruments, beverage and food, PCB printing and other industries dust-free purification workshop at the end of the air conditioning air supply.
HEPA filter testing method
HEPA filter testing methods, through the sodium flame method, oil mist method, DOP method, fluorescence method and particle counting method. The sodium flame method has low sensitivity and cannot detect ULPA filters. The oil mist method is easy to cause filter damage during testing, and cannot be read directly, and the testing period is long. DOP method is restricted because DOP is harmful to human body and classified as hazardous substance. The fluorescence method is currently only occasionally used when testing filters in the field in nuclear industry systems. The particle counting method has become the mainstream method for HEPA filter and ULPA filter testing.
Compared with the oil mist method and the DOP method, the particle size of the aerosol being used as the test aerosol is also different. The first two methods, the test result is at 0.3μm, while the particle counting method to test the results at most penetrated particle size MPPS, the test requirements are stringent, the results are more accurate.
HEPA filter testing standards
The current industry standards that are more highly recognized are EN 1822 High efficiency air filters (EPA, HEPA and ULPA) in Europe and ISO 29463 High-efficiency filters and filter media for removing particles in air in world wide.
Filter HEPA classification
The classification of HEPA filters is based on the overall efficiency and local efficiency test results, which differ slightly between EN 1822 and ISO, as shown in the table below. There are group E, group H and group U, total 7classes filters in EN 1822, but 13 classes filters in ISO 29463.
EN 1822
ISO 29463
Overall efficiency
Local efficiency
E10
-
≥ 85%
——
E11
ISO 15 E
≥ 95%
——
ISO 20 E
≥ 99%
——
E12
ISO 25 E
≥ 99.5%
—
ISO 30 E
≥ 99.90%
——
H13
ISO 35 H
≥99.95%
≥99.75%
ISO 40 H
≥99.99%
≥99.95%
H14
ISO 45 H
≥99.995%
≥99.975%
ISO 50 U
≥99.999%
≥99.995%
U15
ISO 55 U
≥99.9995%
≥99.9975%
ISO 60 U
≥99.9999%
≥99.9995%
U16
ISO 65 U
≥99.99995%
≥99.99975%
ISO 70U
≥99.99999%
≥99.9999%
U17
ISO 75 U
≥99.999995%
≥99.9999%
HEPA testing (Performance air filter test)
In addition to overall efficiency and local efficiency, filters above the H13 class need to be scanned for leak detection one by one. Depending on the filter material used in the filter and the filter use scenario, HEPA filters and ULPA filters are required to have a variety of aerosols to choose from when testing, which places a demand on the aerosol generator. For example, DEHS aerosol is usually used, but when the filter material is PTFE or the filter is used in a semiconductor workshop, PSL small ball solid aerosol is required to meet the testing requirements.
HEPA filter testing equipment
The most recognized test equipment for HEPA/ULPA filters in the market is the TOPAS AFS 150 Automated HEPA/ULPA Filter Scanning Test System and TOPAS AFS 152 Manual HEPA/ULPA Filter Scanning Test System from TOPAS, Germany. Other countries are difficult to manufacture test equipment that can compete with the corresponding incomplete industrial chain and technology.
However, after decades of rapid development, China has formed a complete industrial chain in filtration testing equipment industry, from the sheet metal processing of the shell of the test rigs, to the core components, such as aerosol generator and particle counters, to the hardware and software for the control of test actions. Relying on these technologies, SCINCE PURGE Technology has the ability to manufacture filter testing equipment (for HEPA/ULPA filters and general air filters). And through years of R&D, we have been communicating with our customers to further improve our products. At present, our filter testing equipment and filter media testing equipment are service customers in more than 30 countries and regions around the world, including Italy, USA, Korea, Thailand, India, Russia, etc.
SC-L8023/L8023U is designed and manufactured for HEPA/ULPA filter manufacturers with easy operation and stable testing results. Standard filter is provided for daily calibration of the test system.
