HEPA Filter Leakage Test; HEPA Filter (High Efficiency Particulate Catcher) filters are filters with a large capacity to filter small particles. HEPA filters remove more than 99.9% of particles in the air stream passing through them. These particles are allergens, viruses, bacteria, chemical compounds, dust and many more different particles. HEPA filter, also known as high-efficiency particulate absorber filter and high-efficiency particulate trap filter, is the efficiency standard of air filter. Filters that meet the HEPA standard must meet certain efficiency levels. When tested to MIL-STD-282 at adjusted airspeed, min. It is an extended surface area dry type filter in a fixed frame with a minimum particle retention efficiency of 99.97% for DOP particles with a mass median diameter of 0.3 µm.
HEPA (High Efficiency Particulate Air Filter or High Efficiency Particulate Trap) Air Filter in your ventilation system is a fiber-structured environment consisting of many layers that hold particles of various sizes in the air and fine dust in the environment. After long use or during assembly, air leaks occur in the filters due to damage to their frame. With the Hepa / Ulpa Filter Leakage test, it becomes clear whether such leaks are within the acceptance limits specified in the standard. ULPA Filter, on the other hand, is an extended surface area dry type filter located in a fixed frame with a minimum particle retention efficiency of 99.999% (which is a maximum of 0.0010% particle penetration) when tested according to the methods of IEST-RP-CC007.
The HEPA filter leak test determines the by-pass leaks that affect the cleaning success of the installed system, the failure status of the filters (holes and other damages that may occur on the filter surface and frame connections), and filter leaks (by-pass leaks and other leaks consisting of the filter frame and sealing elements). These tests do not check the efficiency of the installed filter. These are the tests performed by taking samples from the air outlet of the filter, the connection frame of the filter, or if the duct continues after the filter, after the particles (aerosol) are given to the air flow direction of the filters. The HEPA filter tightness test will be applied in cleanrooms and clean areas, after all device connections, equipment and items are completed, during unmanned operation, in existing systems that are already running and have come to test, or when final stage filters are changed. Moreover, Hepa and Ulpa Filter Equipment (DOP) Leakage Test is carried out in accordance with ISO 14644-3:2005, EU Guidelines to GMP:2015.
According to the Hepa And Ulpa Filter Leak Tests standard, it is a test performed by using a photometer and an aerosol generator (with Poly-Alpha Olefin liquid) to check whether there is leakage on the filter surface, gasket and filter cabinet after the installation of HEPA filters, outside the acceptance limits specified in the standard. You should perform these tests at least once a year, depending on the sensitivity of the processes in which HEPA filters are used, and in cases where there is no change in the system. The other name of this test is lntegrity or DOP test. (HEPA Filter – High Efficiency Particulate Air Filter – High Efficiency Particulate Air Filter)
When choosing HEPA filters, care should be taken to ensure that the filter is certified. For filters to be certified, HEPA filters and air cleaners must pass certain tests. By European standards, HEPA filters must remove at least 99.95% of airborne particles. In the United States, at least 99.97% of particles need to be filtered.
The leak test is performed to confirm that the HEPA and ULPA filter systems at the end point are properly installed by verifying that there are no by-pass leaks in the setup, that the filters are undamaged and leak-proof (possible by-pass leaks on the filter surface and gasket, possible leaks in the filter carcass). The effectiveness of the system cannot be checked with this test. This test is done by administering a test aerosol on the filter, followed by scanning the bottom of the filter and the support frame.
First of all, you should determine that the filters to be tested have the appropriate air flow/velocity. You must remove the existing air diffusers and airflow laminators to access the filters. You must give the test aerosol on the HEPA/ULPA filter, following the operating instructions of the generator. Adjust the concentration shown by photometers such as ATI TDA 2G, 2H between 20 and 80 µg/L and record the measured concentration values in the check list. You should set the 100% and zero settings of the aerosol photometer and save it in the checklist you received. You should go to the test position and scan the entire surface of the filter and the cabinet frame, approximately 2.5 cm below the filter surface, with a maximum scanning speed of 0.093m² surface area (Scan Test) in 1 minute. During testing, you should confirm the aerosol concentration, 100%, and zero controls, if possible after a maximum of 5 HEPA/ULPA filter tests. Moreover, you must record them.
“Total Leakage Test” is applied in cases where a screening test is not possible, such as exhaust, duct, air handling unit filters that are difficult to access. This method is applied in unreachable HEPA or ULPA filters or where the mounting structure does not allow a satisfactory screening test. This method is less sensitive than the scanning method. Therefore, performing a Total Leak Test is subject to customer approval. Total leak test with aerosol photometer is performed as follows;
For HEPA Filters (H13 and H14), readings greater than 0.01% of the aerosol concentration are leaks. For ULPA Filters (U15), readings greater than 0.005% of the aerosol concentration are leaks. It is possible for alternative acceptance criteria to be agreed between the customer and the supplier. You can consider the photometer probe readings equivalent to 0.01% of the aerosol concentration as a notable leak. This means replacing the HEPA filter or, if appropriate, making a repair that does not exceed a limited area. In the area where the repair was made, suitability should be retested later.
We recommend that the installation leak test of HEPA and ULPA Filters be retested annually. We recommend retesting the installation leak test of HEPA and ULPA Filters at operational critical points (eg air supplied from aseptic fill line) every 6 months. We recommend retesting in case of damage, replacement or deviation of the field/equipment. Apart from these, you can also consider the frequencies in the ISO 14644-2: 2000 Standard.
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