Air handling units are installations placed in liquid painting booths to meet certain air quality requirements such as pressurization, heat recovery, filtration, heating or cooling, or finally humidity and temperature control.
In painting cabins, the presence of an efficient AHU is essential for three reasons:
- to contain energy wastage
- to ensure a high standard of painting quality by pressurizing the environment and maintaining constant temperature and humidity;
- to guarantee the safety of personnel by keeping the concentration of solvents in the air below a certain threshold.
Each Eurotherm air handling unit is entirely custom designed, taking into account the client’s needs and desired results. In fact, liquid coating has different intrinsic characteristics of humidity and temperature, as well as different environmental elements that are taken into account to achieve quality coating.
How does an air handling unit work in liquid coating booths?
Through the presence of the AHU, the air that is fed into the liquid coating cabin is taken directly from outside the booth, poured into the plenum via an extractor fan and then pressurized in. This way, the air that is used enters filtered, heated or cooled and with constant humidity, into the painting cabin directly from the outside environment and is always expelled outside, thus creating a cycle that is totally independent from the environment inside the factory.
Such system allows simultaneously:
- Great reduction of waste in the thermal management of the warehouse, as the separate ventilation cycle of the booth allows the factory to be heated or cooled without extracting any air from inside it;
- Higher air quality standards inside the coating booth, as the paint is applied to the work piece under optimal chemical-physical and environmental conditions.
The main equipment of air handling units
Eurotherm air handling units can have numerous equipment features such as:
Air heating system
A gas burner or water heat exchanger heats the air in cold periods in order for the cabin to maintain a constant temperature range throughout the year.
Air cooling system
This system is implemented through a water heat exchanger which can be coupled to a cooling unit. In this case, a chiller is used to cool the water to be used inside the air handling unit.
The humidification system, using nozzles that atomize water at high pressure, ensures constant humidity in the desired range. The system works in conjunction with an osmosis or demineralized water production system.
This component has the function of automatically balancing the speed of the air inlet and exhaust fans related to the clogged state of the filters and other factors, so as to keep the air flow rate constant, thus guaranteeing optimal cabin pressurization over time.
The purpose of the heat recovery unit is to achieve a high level of energy saving by crossing the outgoing air flow that liberates from the cabin with the incoming air flow. This way, it is possible to recover part of the heat contained in the outgoing air and return it to the incoming air.
The whole operation of the air handling unit is electronically controlled from the control panel, from where all operating parameters are managed.
The role of the AHU in cosmetics plants
AHUs also play a very important role in cosmetics plants (so-called rotational plants), where painting processes with high quality standards are employed.
In order to avoid contamination between adjacent rooms, each individual zone is pressurized through shutters and other automatic regulation systems. The air flow rate is measured by measuring wings that signal it to the PLC in real time, which in turn regulates the speed by acting on the inverters.
In this case, a single main AHU, aided by support fans and electronic air and pressure drop detection systems, feeds air into each room, thus adjusting shutters and inverters appropriately, in order to manage and maintain the aeraulic balance of the system.
Eurotherm case studies:
- 33-metre long pressurized liquid painting booth for the railway sector equipped with 5 air inlet AHUs and 5 air extraction AHUs for constant temperature and humidity.
- Automatic liquid painting system for the cosmetics field, with AHUs for the aeraulic balancing of all rooms.
- Automatic robotized painting system for plastic components for the automotive sector with input AHUs and air extraction AHUs for each painting booth, 3 in total.
- Automatic robotized painting system for small plastic components for the furniture industry with large AHUs for the aeraulic balancing of all rooms.
Eurotherm creates innovative solutions to meet all needs.
Contact us and tell us about your business for a customized quote.