In China, there is a view that "sub-high efficiency" air filters (filtration efficiency ≥0.5 muon particles ≥ 95%) can be used as end filters for 100,000 class air filters. The reason is that inefficient power supplies are cheap and have low resistance.
In terms of the price of air filters, sub-hepa filters of the same size on the market are 70% to 90% of the price of hepa filters. Sub-hepa filters are not much cheaper than hepa filters. When using sub-hepa filters, the number of air changes in the clean room should be significantly increased. Therefore, the number of air conditioning systems should be large, and the number of air outlets (and filters) should be increased. As a result, the increase in investment is far greater than the difference between efficient and sub-efficient filters.
In terms of resistance, the initial resistance of the sub-hepa air filter is indeed less than the initial resistance of the hepa filter. However, the initial resistance of the end-of-cleanroom filter is not important, as the resistance of either filter is set at 500-600pa. Air filters are designed to last long. The designers believe that the ventilation system will work when the filter is close to the resistance. The difference in initial resistance is virtually irrelevant.
During production, air filters are tested one by one, while sub-hepa filters are sampled only sparingly. They may look different, but their quality is markedly different.
Air-conditioning maintenance personnel often find the following problems after the air-conditioning system is used for a long time:
Fans, heat exchangers, dampers, pipes and other components are heavily powdered and smelly
2. After several years of system operation, the air volume and cold/heat treatment capacity are low, which is difficult to meet the original design requirements;
3. Comfortable black air stains around air outlet;
Indoor personnel complain that the air is dirty and uncomfortable;
5. The high efficiency air filter resistance in the clean room system grows too fast and needs to be replaced even within 1-2 years;
6. For the metal/nylon mesh and chemical fiber non-woven fabric in the current air conditioning, even if not cleaned, the resistance will not continue to rise;
The main cause of these problems is dust, which the so-called washable filters have a limited barrier against. In addition to stopping air conditioning system cleaning or replacing expensive system components, a more effective measure is to add an air filter that is sufficiently efficient. In China, few companies can provide air conditioning system cleaning services. After investigation and research in developed countries, glass fiber bag filter is a cost-effective choice for users.