Virucidal air filters for AHUs capable of neutralizing or destroying viruses

Virucidal air filters for air handling units - capable of neutralizing viruses (including SARS-CoV-2), bacteria, and mold.

Good indoor air quality is vital for everyone present in a building. DELTRI+ air filters provide additional protection against viruses and excellent filtration.

✓  Scientifically tested by Luxembourg Institute of Science and Technology (LIST) and an independent laboratory in France.

✓  Proven efficiency with Eurovent Certified Performance A+ energy class rating

✓  Easy to install and replace

✓  Available in standard sizes

✓  Comparable to filter class MERV 16 (acc. ASHRAE 52.2)

✓  UL 900 certified product

Even Safer

The DELTRI+ filter acts as an extra safeguard by capturing and inactivating viruses.

  • Offers more than 99% reduction of virus load

  • Independently and scientifically proven

  • Uses organic components (citric acid)


Quickly improve existing AHUs and indoor air quality with DELTRI+ filters before opting for more extensive, costly upgrades to ventilation systems.

  • Simply replace existing filters

  • No modifications to unit required

  • No additional power supply needed


There’s no need to worry about significantly increasing energy costs.

  • Low energy consumption (Eurovent A+)

  • Low pressure drop

  • Market-leading dust holding capacity (ISO ePM1 90%, comparable F9, EN779)

Citric acid

Effective in destroying viruses, safe for humans.

The virucide in DELTRI+ is citric acid. An organic compound widely used for cleaning and sanitising. The human body produces it for its own metabolism, and citric acid is used for food and drinks.

Our offering

Customers can choose from many DELTRI+ filter types:

  • Standard AHU filter sizes

  • An optional order item for new & existing Systemair AHUs

  • Replacement filters for AHUs – independent from their brand

How does the DELTRI+ filter work?

The deactivation process of a virus that comes into contact with the filter surface.

Viruses touches the filter surface

The filter damages the virus

The virus is inactived and can't reproduce

DELTRI+ is a multi-layer progressive filter, where the first layer is coarse, and all subsequent layers are finer than before. The virucide is “stitched” to the last and most dense layer of filter material with an advanced plasma treatment.

If the filter does not capture a virus, it will touch the filter material when passing through. A short moment of contact is sufficient for the virucide to damage the virus, disabling the virus’ ability to reproduce. More than 99% of all viruses are neutralised after passing through the filter.

How the filters were tested

A great effort was done to prove that the DELTRI+ filter works and is safe. Several independent laboratories have provided more than 15 reports and certificates, all of which are available upon request.

Tests were done on:

  • Material safety

  • Virucidal effect

  • Filtration efficiency

  • Dynamic behavior

Virucidal effect

The virucidal effect has been determined according to several standards and test methods. Independent third parties have tested the effect of the virucide (EN 14476) and its effect when applied to a textile (ISO 18184).

According to ISO 10705 the Virus Load Reduction (VLR) has been measured:

  • VLR after 1 hour = 99,999 [%]

  • VLR after 12 months = 99,21 [%]

Filtration efficiency

The filters have been tested according to ISO 16890. The filtration efficiencies measured:

  • ISO ePM 1 = 90 [%]

  • ISO ePM 2,5 = 95 [%]

  • ISO ePM 10 = 95 [%]

Filter class (according to ISO 16890) is defined as ISO ePM1 90%. This is comparable to filter class F9 (EN 779) and MERV 16 (ANSI/ASHRAE 52.2).

Dynamic behaviour

The dynamic performance of the DELTRI+ filter has been tested with live viruses, bacteria, and moulds. Air was contaminated with colony-forming units (CFUs) and subsequently pumped through the filter. The air leaving the filter was collected and the amount of CFUs that remain in the air were measured. After 5 minutes, the following values for the remaining CFUs were measured:

  • Bacteria : 0 [%] --> 100 [%] efficient

  • Mould: 2,5 [%] --> 97,5 [%] efficient

  • Viruses: 0 [%] --> 100 [%] efficient

Dletri+ NA Brochure Cover

How long does this filter last?

Third-party tests at Luxembourg Institute of Science and Technology (LIST) have shown that the filters should last 12 months. Systemair generally recommends shorter replacement cycles – independent of the filter solution.

To ensure that the virucidal treatment and coating does not get affected during transportation and storage all filters are packaged separately. The 12 months lifetime starts when you unpack and start using the filter.

­Find more about Deltri+ filters

Download the brochure and get more information about this innovative air filters!


Is this filter effective against COVID-19?

Tested by the Luxembourg Institute of Science and Technology (LIST), DELTRI+ Technology significantly reduces biological aerosols including SARS-CoV-2. However, the technology’s reliability ultimately depends on how well you generally maintain your units. It is also not a substitute for recommended COVID19 prevention measures in your markets, such as wearing masks, increasing ventilation rates, and the like.


Does the virucidal treatment only work against the viruses captured by the filter?

ePM1 90 captures 90% of all particles between 0.3 and 1 micron. This is a general description of a filter classification. However, it is not true that the 10% that is not captured has no contact with the filter material. A brief moment of contact is sufficient to neutralize the virus. So, it's not about catching the virus; it's about contact with the virus. 

A DELTRI+ filter is composed of different layers, and the multiple layers improve the dust holding capacity. The first layer through which the air passes is coarse, and each subsequent layer is finer, also known as a progressive filter. Due to this construction, the filter has a large dust absorption capacity (719 grams, measured according to ISO 16890). 

The large particles mainly remain behind on the inlet side of the filter, and the finer particles will remain behind further in the filter. As a result, the exit side remains free of large dust particles. The virucidal treatment is on the last layer and will, therefore, always be active on the cleanest side of the filter. Even virus particles that can travel through the filter in this way will make contact with the virucidal layer.


How long can a virus remain active in traditional filters?

A virus can remain viable for a very long time depending on the surface which it is on and the humidity, and other factors. As explained by Systemair in previous webinars, a virus can be active for up to 28 days on steel in a dry condition if the humidity is less than 30%. There is no evidence that a virus will be inactivated after 48 hours in a filter.

Are the components used in the virucidal treatment safe for humans?

The active ingredient (i.e., the virucide) used in the DELTRI+ filter is citric acid. Citric acid is an organic compound that is also produced by many organisms. An example is the citric acid cycle that plays a major role in our metabolism. 

Citric acid has also been widely used for cleaning and sanitizing. It does not cause any known allergic reactions and it is not toxic. The citric acid used in the production of the DELTRI+ filter is suitable for consumption. It is also used in foods and beverages for food preservation and flavour. 

The unique thing about this filter is the production method, in which the citric acid is firmly attached to the filter material. This is the only way to guarantee the virucidal effect for a year. The virucide will not come off and will therefore not enter the airflow; it cannot be smelled. 

So, there is no dangerous chemical treatment. Even if the citric acid were to come loose from the filter, it is harmless. The filter material is also used to produce medical mouth masks placed directly in front of the mouth and nose. The operation and safety of these products have been extensively tested and proven.


Are there standard protocols in the testing of virucidal filters? 

The filter market does not have a fully adapted norm for virucidal filters. The independent Luxembourg Institute for Science and Technology (LIST) has carefully searched for the best testing method available. In tests conducted, aerosols containing a virus are sprayed onto the filter material. This corresponds to the way a virus would float through the air. Here lies a new opportunity for the entire filter market to set up a virucidal filter norm. 

In addition, many other tests have also been performed to determine the function of the virucidal filters. This includes accelerated life tests, tests in dry and wet conditions and tests with dirty filters. These tests confirm that the virucidal layer has a proven lifetime of at least 12 months, demonstrating virus load reduction of more than 99%.

To approach the real use of a filter in an air handling unit, the standard EN17141 (for air purifiers) was modified. During this test, air was loaded with pathogens and pumped through the filter. This test confirmed prior results on the VLR, but also showed that the filter is active against bacteria and mould.

Will DELTRI+ allow us to reactivate recirculation functions in our AHUs?

In many COVID19 prevention recommendations, including Systemair’s, it is recommended to turn off recirculation functions in AHUs and switch to 100% fresh air supply mode.

Recirculation was utilised in many situations before the pandemic to save energy (e.g., during low occupancy at night in a building or when CO2 levels in a room are low). In an intelligent ventilation system, this was “normal” and made sense.

Many building operators and owners have contacted us over the past months as they would like to activate recirculation functions again. First, however, they would like to have the confidence to do so.

DELTRI+ is a straightforward solution in this respect. While high-quality ePM1 filters already help, the DELTRI+ technology offers an additional safety net, enabling (partial) recirculation again to save energy.


The information provided about Deltri+ is according to the product specification of the manufacturer Deltrian International.

The illustrations are for guidance only. Information is provided for general informational purposes only and is not a substitute for professional advice. Accordingly, before taking any actions based upon such information, we encourage you to consult directly with the manufacturer Deltrian International. Systemair as a Seller cannot provide any kind of advice.

We inform that the tests were carried out under standardized test conditions and that the effect of Deltri+ may differ between installations and/or conditions of the environment/building.

All information about Deltri+ is provided in good faith, despite the greatest care, editorial errors or translation mistakes cannot be completely ruled out, therefore no liability can be accepted for cases of negligence.