Highlights on UV Recirculation

A UV recirculation (also called a closed irradiator) is a device that serves to disinfect indoor air in the presence of people. The recirculation takes the breath from the room, drives it through the irradiation chamber (“ultraviolet boiler”), and throws it back into the same room. In the irradiation chamber, the air is exposed to ultraviolet radiation and disinfected.

There are key characteristics when using the device are ensuring the multiplicity and providing the UV dose.


The effective operation of the recirculation is related to the volume of the room in which it operates. One or more recirculation in one place should be 4-6 times higher than the amount of the treated room. Then he will be able to let through himself the entire volume of air in the room every 10-15 minutes. This is very important since the people in the room serve as potential sources, and the air after expiration must pass decontamination as soon as possible. For example, for a room of 36 m 2 with three-meter ceilings, it is necessary to use a recirculation or recirculation with a total capacity of about 500 m 3 / hour.


For each type of microorganism (for example, 99.9%), a specific UV dose is required. The treatment of UV radiation is the product of the exposure time to the radiation intensity.

For a given UV power and a given airflow (productivity), the larger the volume of the irradiation chamber in the recirculation, the more time the air is exposed to ultraviolet radiation, the higher the UV dose receives.

It is also understood that the higher the intensity, the higher the UV dose, like the UVGI system (ระบบ uvgi which is the term in Thai). The intensity can be increased by increasing the number of lamps (and then the power consumption increases), or you can use special coatings on the walls of the chamber, which will not absorb, but reflect ultraviolet back into the volume of the “boiler,” thereby increasing the intensity. To cover the walls of the reactor using various materials that reflect ultraviolet light.

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