The construction of the INDUCTair® hoods is based on the concept of air extraction as a carrier of harmful substances—heat, grease particles, etc.—in the smallest possible amount and with the highest possible concentration of these pollutants. For this purpose, the so-called induction system was developed, and a brief description follows.
The hood features a one-sided suction and two-sided exhaust radial fan built into it. This fan draws in a small amount of air from the surrounding area (2 to 3% of the extracted air). This air is then blown out as a primary flow at the locations of warm rising currents, using small adjustable nozzles directed towards the corresponding extraction elements. The loss of airspeed in the incoming airflow is accompanied by significant induction of warm rising currents and the formation of an overall airflow with an increased concentration of pollutants. It is advisable to achieve maximum induction of rising currents in areas with elevated air temperature.
To achieve this, the direction of the primary airflow (from the nozzles) must be set in such a way that the overall airflow best covers the corresponding extraction element, and the speed of the primary air must be adjusted so that the total airflow volume does not exceed the capacity of the extraction elements.
For the extraction elements, INDUCTair® hoods are equipped with stainless steel grease traps, featuring a layered expanded metal filling with a separation efficiency of 85–87%. The size of the traps is designed to allow for cleaning in a standard dishwasher. The height of the trap is determined according to the distance from the induction nozzles to ensure perfect capture of the overall extracted airflow.
The fluorescent lighting is built in such a way that it does not interfere with the accumulation space of the hood and is covered by opal vinyl glass (alternatively, polycarbonate with a higher softening temperature).
For draining condensate, the standard design includes holes with a plug shaped so that it does not protrude from the bottom surface of the drip tray. This condensate drainage solution was adopted based on recommendations from the Institute for Safety Research. The reason for this recommendation is the frequent head injuries caused by protruding parts (spouts, taps) during cleaning and maintenance of the hoods. By agreement, a discharge nozzle with a thread for fitting a valve or other draining method can be welded on.
Function of the Hood
The focus of the hood development was on increasing the extraction efficiency, reducing power and heat consumption, and synergistically and rationally supporting natural physical phenomena:
- The extraction openings can only draw air from the immediate vicinity.
- Increasing the concentration of pollutants in the extracted airflow increases the extraction efficiency.
- The decrease in the incoming airspeed is significantly slower than the decrease in the speed of the drawn-in air.
INDUCTair® extractor hoods use a nozzle system located above the heat sources, injecting air flows into the hood that are directed toward the respective extraction elements.
The injected airflows induce underpressure that leads to the induction of warm rising currents (including water vapor, grease particles, and aromatic gases).
The momentum of the injected air moves the induced pollutants into the area of effect of the extraction elements. This significantly increases the concentration of pollutants in the extracted air and allows for a reduction in its volume.
Continuous induction of warm rising currents and the effect of the extraction elements are limited to areas with significantly increased concentrations of pollutants, increasing the qualitative difference between the air in the space and the air being extracted.
The overall airflow induced by the system (for a given distance between the nozzle and extraction element) is determined by the amount of injected air and must never exceed the capacity of the extraction elements.
Natural physical phenomena such as the rising of warm or humid air are not disrupted but are supported to a certain extent, thus achieving stabilization of the rising currents.
