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Air Filtration For Covid-19 Prevention

Psyctotherm suggests complete solution for Covid-19 Prevention. 

The existing problem:

Several studies have indicated that the HVAC systems of some ships, especially at older vessels, are prone to microbial or virus contamination. Small spaces or densely occupied communal areas with lack of fresh air extend the problem.

Due to the complexities of shipboard HVAC design, proper filtration offers the best method of keeping the system clean and preventing the accumulation of microbial or virus contamination.

The new factor:

The new coronavirus (SARS–CoV-2) is a respiratory virus which spreads primarily through droplets. These droplets are too heavy to hang in the static air and usually fall on the floor quickly, but the air recirculation of the A/C system could carry them across the ship.

According to World Health Organization air recirculation of A/C systems potentially can bring back the virus into the supplied air.

Coronavirus particles nominal diameter is from 80 to 120nm, thus they cannot be stopped by standard air filtration of AHU units.

Several cases already prove that the new coronavirus quickly spreads inside a ship.

The solution:

High efficiency filters can be used to protect the crew and passengers from the new coronavirus. But should consider the following:

- Final filters should be classified as H13 or H14 according to EN1822. This guarantees a removal efficiency of 99,95% (H13) or 99,995% (H14) of 100nm particles.

- These filters are high pressure drop, thus require an excellent sealing with the filter case. If they are used with existing filter cases most of the air will by-pass the filter.

- High pressure drop also requires a more efficient fan. Standard vessel A/C fans cannot cover the additional pressure drop; thus, fan static pressure should be boosted with a new compact and efficient fan.

- High-efficiency HEPA filters will load with dust and particles very quickly, thus requiring frequent filter changes. In order to avoid this, pre-filters should be installed before the high-efficiency filters, that will prevent higher sized particles to contaminate the high-efficiency filters.


PSYCTOTHERM can suggest a complete solution that will upgrade the existing AHU unit with the following characteristics:


  • Additional booster fan with use of direct driven EC plug fan to cover the higher pressure drop. Plug fan can offer high efficiency with small size, leaving enough size for the 3-stage filtration. EC fans speed can be controlled according to the required air-flow for energy savings. If a complete fan replacement is necessary high efficiency belt driven fans with airfoil blade are used.


  • New filters with new enclosure box and/or mountings with 3-stage filtration:
    • Stage 1: Z-type prefilter F6-EU6 65% for larger dust particles.
    • Stage 2: Bag filter F7-EU7 85% for smaller dust particles (84% efficiency).
    • Stage 3: Final HEPA filter H13 (99.95% efficiency) with proper sealing.


  • Electronic control module with PLC that monitors the pressure drop on the filters and the rotational speed of the electronic booster fan.
    • As an option add-on cassette HEPA filters can be installed on the air duct discharge inside the cabin units.

    You can send us your AHU drawings and specifications

    in order to receive our Proposal!


    Dr. Eng. Pantelis Bakalis

    R&D Dept.


WIMA Worldwide Industrial &
Marine Association

14, Skouze str. Piraeus
Tel: +30 210 4122834
Fax: +30 210 4122891
email: info[at]

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