In order to ensure the purification effect, the exhaust air volume should be calculated strictly according to the suction wind speed of the exhaust hood in actual design. The suction wind speed of the hood is usually not less than 0.5 m/s, and the minimum exhaust air volume is usually calculated according to the following formula: L = 2000 pH

Among them:

L—— exhaust air volume of exhaust hood, m3/h;

P refers to the perimeter of the hood opening (excluding the wall edge), m;

H —— distance from hood mouth to kitchen mouth, m

After the exhaust air volume is calculated by the above formula, the suction speed of the range hood is calculated according to the area of the range hood to ensure that the suction speed of the range hood is not less than 0.5m/s. ..

In practical engineering design, estimation methods are often used. According to the provisions on kitchen ventilation in Technical Measures for HVAC Design of Civil Buildings, kitchen ventilation can also be determined according to the following ventilation times:

Chinese kitchen: L=40-50 (times/hour);

Western kitchen: L=30-40 (times/hour);

Staff canteen: L=25-35 times/hour

The term' not counting the side against the wall' here means that the side of the exhaust hood against the wall forms a closed space with the wall, and this side has no air to supply the exhaust hood, just like the other four sides, so it is not necessary to calculate the side length of the side against the wall.