The HEPA filter is widely used
H13 and H14 are two typical filter levels of HEPA filters and are the most used filter levels in various industries, with the latter having a retention rate of 99.995%@0.3um.
When to replace it?
Appliances like an air purifier or vacuum cleaner have an air filter replacement indicator function, so if the filter replacement light comes on, it is time to replace air purifier filters or vacuum cleaner filters like pre-filters, activated carbon filters, and HEPA filters.
In the industrial and commercial setting, When the resistance value of the HEPA air filters is greater than 450Pa or when the airflow speed of the air outlet surface is reduced to the minimum, even after replacing the primary and medium efficiency filters, the airflow speed still cannot be increased; or when the leakage of the surface of the HEPA filter cannot be repaired, it is necessary to replace the filter with a new HEPA filter.
If there is no above situation, the HEPA filter can generally be replaced once in 10 months to once a year according to the environmental conditions or air quality.
Of course, HEPA filter maintenance and replacement are only a few things. The filter (filtration layer) load and the upstream and downstream pressure differences are also significant.
If the differential pressure upstream and downstream of the filter increases, the energy demand of the air supply and exhaust system will increase so that the necessary number of air changes can be maintained.
Such upstream and downstream pressure differences may increase the performance limits of the ventilation system.
Front-end filters are usually medium-efficiency filters like F7 and F9 to protect the HEPA filters. These medium-efficiency filters must be changed regularly to protect the HEPA filters from clogging.
The lifetime of HEPA filters
The air filter is the core part of the air conditioning purification, HVAC, or ventilation system.
The filter creates resistance to the air. As the dust accumulation in the filter increases, the filter resistance will increase too. When the filter accumulates too much dust, and the resistance becomes too high so that the amount of air passed through the filter decreases, or the filter is broken by penetration and the filter resistance increases to a specific specification, the filter will be scrapped.
Therefore, when using a filter, it is essential to understand its life cycle. Without damage to the filter, its final resistance generally determines its service life.
HEPA filter lifetime is in about a year, the most reasonable basis: particle counters to detect whether the cleanliness of the room meets the design standards. If the number of particles exceeds the standard, the HEPA filter should be replaced.
The high-efficiency filtration system is generally configured with a primary and medium-effect filter to protect the HEPA filter. Some of the primary filters are washable. If you change the primary and medium-effect filters for a short time, it will affect the service life of the HEPA filter.
If a differential pressure gauge is installed at the end of the filtration system, you can know whether it is time to change the filter based on the differential pressure gauge. If not, generally, the primary filter will be replaced in 1~3 month; the medium-effect filter will be replaced in 3~6 months, and the HEPA filter will be replaced in about ten months to 1 year.
If the quality of the primary and medium-effect filters is good and filters are well maintained, the life cycle of the HEPA filter will be longer. But there are no permanent filters.
Notes on the use of HEPA filters
1. Make sure to determine the pressure value, which is a hard rule, and stay within the filter’s highest pressure value to ensure the HEPA filter’s practical use and the safety of the use process.
2. Before installing the HEPA filter, the clean room must be cleaned in many aspects, using a vacuum cleaner with ultra-clean filter bags for vacuuming. If installed in the ceiling, the inside of the roof must also be cleaned very well.
3. After the cleaning is done, the trial run of the purification and ventilation system must be carried out for more than 12 hours, and then a high-efficiency particulate filter can be installed after all the pipes are repeatedly cleaned.
4. The transportation and storage of HEPA filters should be placed according to the air filter manufacturer’s requirements. During the transport, it must be placed gently not to affect the filter’s performance.
5. Before installation, the HEPA filter must be checked, including whether the design and size meet the requirements and whether the technical performance meets the design requirements, etc.
6. When sealing between the HEPA filters and the filtration system, the contact surface, the surface of the filter frame, and the liquid tank must be cleaned.
Notes on HEPA filter installation
1. Due to the unique brittleness of glass fiber paper, the first thing to consider in the use and installation was not contact with sharp objects and repeated rubbing. To keep the filter media intact.
2. The glass fiber material should be used with as little contact as possible with water or other corrosive liquids so it will not affect its regular use.
3. Requires good clean equipment in the plant.
4. The HEPA filter should be used reasonably to ensure that each filter does not bear an excessive dust load.
5. Conduct a visual inspection before installation to detect any damage to the filter material and appearance, and test the sealing condition after installation to detect leaks strictly.
