The required performance is determined by the dimensions of the kitchen hood, that is, the volume of air space. It is believed that ventilation should provide a 10-fold in the air for one hour. For example, the kitchen area of 8 m2 and a height of 2.5 m (volume – 20 cubic meters) requires a model with a maximum capacity of 200 cubic meters / h. At the same time we must not forget that in performance exhaust is greatly influenced by the height of the building, floor, on which the apartment is located, the length of the duct, its pollution, temperature drop in the ventilation rate of cooking, number of smokers in the kitchen. Newcastle University brings even more insight to the discussion. As a rule, taking into account the possibility of any adverse factors that increase the performance of another one and a half to two times (just in case). When comparing the performance extracts of different manufacturers should pay attention to how to measure it.
In one case, the measured performance exhaust that is not connected to the duct, ie, "Free-air outlet (FB – Free Blow). In the second way regulated to IEC 61 591, measurements are taken with the attached ductwork of a certain length and cross section. In the second case are smaller numbers that are more consistent with reality. For example, performance of most single-Cata cooker hoods in measuring "free-air outlet" -1020 cubic / h, and only 851 cubic meters / hour – as measured by the method of IEC 61 591. Reputable manufacturers usually produce both of these figures.