DUCT CLEANING SERVICE

Ship ventilation systems have different requirements depending on the destination of the compartments and the type of ship. Thus, there are compartments where natural ventilation is sufficient, while other compartments require forced ventilation via extraction and/or introduction fans, and for other compartments ventilation is via an air conditioning system.

Therefore, according to the classification society's rules, special compartments in which flammable or toxic gases may be released must be equipped with mechanical exhaust ventilation. The air renewal rate required is different, as it is necessary to reduce the risk of flammable or toxic gases escaping and accumulating.

Other rooms in which the installed equipment needs air to operate must be equipped with independent mechanical supply or supply and exhaust ventilation, which must guarantee the air needed to operate and cool the equipment. Rooms in which there are no special requirements from equipment manufacturers or classification societies are only provided with natural ventilation.

The lounges are generally equipped with common ventilation and air conditioning systems to ensure a suitable climate for crew and passengers. The minimum fresh air flow required is related to the number of people, but is no less than 40 per cent of the total air flow. In addition, there are areas such as the galley, toilets, canteens and laundry where recirculation is not permitted. Common ventilation and air conditioning systems, which are equipped with a common air handling unit (AHU), have the advantage that noise inside the rooms served is low and equipment maintenance is fairly easy because the main equipment is installed in a dedicated room.

However, it should be noted that in the case of ordinary ventilation and air conditioning systems, which mix room air with fresh air and recirculate it back into the rooms, the spread of disease through the air conditioning system can be high. The spread of disease through the air conditioning system can be reduced by adding HEPA filters, but in this case the protection is limited and the fans must have increased pressure. If HEPA filters are installed in the return ventilation duct and if the air handling unit (AHU) is not equipped with a recirculation fan, the pressure inside the rooms will increase by 150-900 Pa due to the pressure drop in the new filter. Therefore, the system must be provided with an additional exhaust fan.

The spread of disease through air conditioning systems can also be reduced by adding disinfection with organic products that are not harmful to health, among other options such as ultraviolet (UV), the latter of which is much more expensive than the former and environmentally friendly, and "more than 90 per cent of the SARS-CoV-2 virus, more than 97 per cent of the Influenza A virus and 100 per cent of Legionella pneumophila can be inactivated". However, according to IES, if the UV exposure time is increased by 50 per cent, the disinfection efficiency will increase from 90 per cent to 99 per cent.

Many studies have confirmed the high level of aerosol and droplet transmission of the SARS-CoV-2 virus. Researchers have reported that the virus spreads to all floors through the ventilation duct and suggested aerosol transmission. reports of aerosol transmission of SARS-CoV-2, especially in enclosed spaces, we conclude that aerosol transmission of SARS-CoV-2 due to poor ventilation may explain the community spread of the disease.