In restaurants, catering kitchens, and food plants, relying on an electrostatic precipitator or a wet scrubber alone often still lets residual grease and odor escape, which leads to the familiar chain of neighbor complaints, environmental inspections, and grease buildup that can catch fire in the ducts. UV photolytic purification takes a different route: it uses ultraviolet light to break down fume molecules right there inside the duct, rather than merely 'capturing' the grease.
What 185 and 254nm Each Do
- 185nm: This energy hits the oxygen molecules (O₂) in the air, dissociating and recombining them into ozone (O₃) and reactive oxygen (atomic oxygen), both strong oxidants.
- 254nm: This wavelength is absorbed by most hydrocarbons (grease) and by ozone. On one hand it directly breaks the chemical bonds of grease and odor molecules; on the other, it takes part in the ozone cycle, keeping the oxidation going.
Ozone and free radicals are powerful oxidizers. They oxidize large grease molecules and VOC odor molecules into smaller, easier-to-handle substances such as carbon dioxide and water, so they bring down both fume concentration and smell at the same time, while also reducing duct grease buildup and lowering fire risk. The whole thing is essentially a combined reaction of photolysis and ozonolysis.
Performance Depends on Residence Time
UV photolysis is not 'install it and everything is 100% clean.' Laboratory research shows that across a range of typical VOCs, at a residence time of about 53 seconds, removal rates fall in a band as wide as 13% to 97%, with the spread depending on molecule type, lamp dose, and residence time. That points to a key design principle: the duct has to leave enough reaction residence time and a long enough lamp irradiation section. If the air moves too fast and the irradiation section is too short, the reaction simply never finishes, and performance suffers. This is also the most common failure we see in the field: plenty of lamps installed, but the airflow is too high and the residence time falls short.
A Central Catering Kitchen Scenario
Here is an example. A central catering kitchen deep-fries and stir-fries in large volumes every day; a noticeable greasy smell often hung around the exhaust outlet, and the rooftop exhaust duct built up a thick layer of grease within half a year. They later added a UV photolysis section alongside the existing electrostatic and wet-scrubbing stages: the fume first passes through the front stages, where large grease droplets are captured, then enters the UV section, where the remaining small-molecule grease mist and odor are oxidized and broken down. The key is to place the UV section where there are fewer droplets and the airflow is stable, and to get the residence time right; the odor and the duct grease buildup usually improve noticeably. It bears emphasizing that the UV section 'reinforces' the upstream capture equipment, it does not 'replace' it.
Where It Fits
Commercial kitchens, food processing, baking, and central catering kitchens—venues where fume and odor tend to be heavy—are all good fits, and it is usually used together with the existing exhaust system (the front stage handles droplets with an electrostatic precipitator or wet scrubber, the UV section handles odor and small molecules) rather than swapped in on its own.
Is Installation a Hassle?
Most sites can be worked on during off-peak hours or a regular closing day. Before starting, we do a site survey to confirm the capture hood, duct dimensions, airflow velocity, and power locations, and to work out how long an irradiation section needs to be reserved to reach the target removal rate—keeping any downtime to a minimum. TingHao is based in Nanzi, Kaohsiung, serving restaurants and food businesses across Kaohsiung, Tainan, Pingtung, and southern Taiwan; if you would like an assessment, you can start by sending us site photos over LINE.