Room air purifiers are still in demand for pandemic protection. However, the multitude of products on offer makes it difficult to find the right solution. The recommendation is: "6 air changes per hour and filter class EN 1822 H14". A number of suppliers, including well-known International brands for household appliances, rely on cheap OEM produced devices. Their consumer price is usually well below the 30,000 THB mark. According to our market observations, a similar but questionable filter concept can be found in many cases with imported devices. In addition to flimsy pre-filters and undersized activated carbon filters for odor filtration, filters are also used there that are referred to as HEPA and are nevertheless not suitable for virus and aerosol filtration.
The term HEPA (high-efficient-particulate-air filter) is unfortunately not a protected term.
If the filter is not further identified by the standard EN1822 or ISO 29463 as well as the filter class H13, H14, ISO 35H, ISO 40H or ISO45H are not named, it must be assumed that the filter in question is a product of inferior quality.
Typically, "HEPA filters" are very inexpensive imported room air purifiers with a black cardboard frame and a circumferential seal on the frame. There are no standard declarations, serial numbers and test certificates or other markings on the filter.
These filters generally do not meet the requirements for HEPA filters according to EN 1822, namely classes H13 or H14. On the one hand, the filters of cheap room air purifiers are often not tightly glued and, on the other hand, the frame tends to deform and leaks through gaps.
The import room air cleaners themselves usually do not offer a tight filter mount, so that leakage occurs on the tightly dimensioned sealing surfaces. Since many import room air cleaners are also only equipped with weakly dimensioned fans, no mechanically operating filter media can be used, as it is the case with standard HEPA filters.
Retrofitting those air purifiers with functional and standard-compliant filters is usually difficult because the weak fans only allow very small filter pressure differences. Therefore, mostly coarse-fiber, inferior filter media with correspondingly low resistances are used in these devices. The media is electrostatically charged to boost the efficiency. However, this is not reliable to ensure the efficiency of these filters against viruses and infectious aerosols in the long term.
The performance of such filters cannot be compared with actual HEPA filters according to the EN1822.
These days we have tested some “HEPA filters” from imported devices and the results are sobering. The series of measurements showed that the filters are at most suitable as pollen filters, but are not suitable for the safe separation of viruses and aerosols, as the degree of efficiency is not sufficient in case of doubt.
According to the operating instructions, the product in this example achieves an efficiency level of approximately EN1822 E10 and would therefore be at most an EPA filter. A measurement according to EN1822 / ISO 29463 was not possible due to a large number of leaks. A test according to ISO 16890 only resulted in a separation efficiency of ePM2.5 70%. This filter qualifies for house dust, lint, textile fibers and pollen. Such a filter is not suitable for infection protection
Unfortunately, we have noticed that schools, doctors and care facilities are increasingly using such devices out of misleading information conveyed by commercials.
Therefore: take a close look at the device and the filters. For filters of class EN1822, the following apply among others. the following labeling requirements on the filter:
- Name of the manufacturer, trade name or other information to identify the manufacturer;
- The type and serial number of the filter;
- the test standard (e.g. EN 1822 or ISO 29463);
- Filter class - for protection against infection EN 1822 H13 or better or ISO 29463 ISO 35H or better;
- Nominal air flow rate on which the filter class is based.
If this information is missing from the labeling of the filter, the dealer information must be questioned. If in doubt, have an individual test certificate for the corresponding serial number of the filter presented to you. The test must have been carried out in accordance with EN 1822-4 or ISO 29463-4.
The filters themselves must be securely pressed in the device by means of a seal on the front of the frame on a flat sealing surface in the housing. Circumferential foam-like seals on the wall surfaces are unsuitable for this purpose, since they do not provide a sufficient seal.
Upgrading imported devices is difficult - but not impossible. We have special filter media that are mechanically extremely effective and yet offer sufficiently low pressure differentials. From a purchase quantity of > 500 filters, we can offer individual upgrade solutions.