Air, water, surface decontamination units and other equipment used in transport are complex technical products capable of operating in harsh climatic conditions, withstanding vibration and shock loads and compatible with the vehicle’s electrical network. The size and weight of the equipment is usually strictly limited. In addition, there is a large amount of dust in the ventilation and air conditioning system, which makes it very difficult for conventional decontamination equipment to operate.
All this makes the development of transport disinfection systems a difficult complex task, with which the employees of the design bureau of LitTransService Ltd. have been successfully coping for more than 10 years.
Based on many years of experience, the company’s specialists have analysed various disinfection technologies such as:
- Filtration
- Electroporation
- Photocatalysis
- UV radiation
Based on multilateral analyses, it was found that for transport applications, air disinfection by ultraviolet radiation is the safest, most effective and reliable method.
The technology of ultraviolet disinfection of air, water and surfaces is based on the bactericidal action of UV radiation. Ultraviolet radiation is electromagnetic radiation with a wavelength in the range from 100 to 400 nm. There are several parts of the UV radiation spectrum with different biological effects: UV-A (315-400 nm), UV-B (280-315 nm), UV-C (200-280 nm), vacuum UV (100-200 nm).
Of the entire UV range, the UV-C section is often referred to as the bactericidal section because of its high disinfecting efficacy against bacteria and viruses. The maximum bactericidal sensitivity of microorganisms occurs at a wavelength of 265 nm.
UV disinfection is a physical disinfection method based on photochemical reactions that cause irreversible damage to the DNA and RNA of microorganisms. As a result, the microorganism is killed or loses its ability to reproduce (inactivated).
UV disinfection technology can be used both in water treatment and wastewater treatment systems and in air and surface disinfection.
The main advantages of UV technology:
- high disinfection efficiency against a wide range of microorganisms: bacteria, viruses (including COVID-19) and protozoan cysts;
- no influence on physico-chemical and organoleptic properties of water and air, no by-products are formed, no danger of overdose;
- low capital costs, energy consumption and operating costs;
- UV units are compact and easy to operate, and do not require special safety measures.
The main industrially used sources of UV radiation are high-pressure mercury lamps and low-pressure discharge lamps, which come in two varieties – mercury and amalgam, as well as LEDs. However, the use of mercury lamps in transport is unacceptable due to safety requirements because of the strong toxicity of mercury. Therefore, LitTransService LLC uses only amalgam lamps of its own design, specially designed for use in transport.
Amalgam lamps have high efficiency (35 % compared to 9 – 12 % of high-pressure lamps) and life, which allows to create, on their basis, energy-efficient equipment. In addition, amalgam lamps do not contain explicitly and are therefore safe in case of damage.
Many manufacturers of germicidal lamps use standard quartz glass, which leads to ozone generation during operation of the lamp. This is unacceptable in case of air disinfection in the presence of passengers. LitTransService LLC uses special quartz with additives that prevent ozone generation in their lamps.
In some cases, when used on transport, electric power is limited, so even the use of powerful amalgam lamps efficiency may be insufficient, to solve this problem the company “LitTransService” applies special coatings that enhance the action of disinfection.
Enhanced disinfection efficiency
To increase the disinfection efficiency, a special coating of the internal walls of the disinfection chamber has been developed and applied, which provides an increase in the intensity of UV radiation up to 30%. Reflective properties of various materials with respect to UV radiation are well known, but the main issue is the realisation of a durable coating on the metal body. The solution patented by LitTransService allows to solve this problem successfully.
To provide additional disinfection effect and at the same time prevent UV radiation from escaping beyond the UV module, special grids with photocatalytic coating based on titanium dioxide are used.
UV rays hitting the surface of the lattice cause catalytic processes with the formation of short-lived radicals, which affect the shells of microorganisms, causing their death.
Tests
The use of UV disinfection technology makes it possible to create equipment that meets all the requirements for units for both railway and road vehicles.
Numerous know-how is applied in the development process to create a perfect product that has no analogues.
The equipment development process requires a large number of tests:
- test for resistance to climatic external influencing factors
- mechanical external factors resistance test
- electromagnetic compatibility test
- electrical safety test
- fire safety test
- Laboratory tests of biosafety and disinfection efficiency
- Field testing of prototypes
- Operational tests in normal working mode
At the end of each type of test, a protocol is issued by a specialised organisation.
Upon completion of the tests, an acceptance commission is held with the involvement of leading specialists of the research institute, representatives of vehicle manufacturers and operating organisations. After signing of the acceptance committee act, serial production of the equipment is started.
On average, it takes 2 years from conception to putting a new model into production.
