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 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.
- 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 required a more efficient fan. Standard vessel A/C fans are not designed for high pressure operation,thus, fan should be replaced with a new compact and high pressure fan.
- A high-efficiency 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.