Legal analysis: the minimum removal efficiency limit value of the oil smoke purification facilities of the catering units is divided into three levels of large, medium and small according to the scale; the scale of the catering units is divided according to the number of benchmark stoves, and the number of benchmark stoves is discounted according to the total heating power of the stoves or the total area of the projected surface of the exhaust hood stoves. Each benchmark stove corresponding to the heating power of 1.67 × 108J / h, corresponding to the exhaust hood stove surface projection area of 1.1m2.

Legal basis: "Catering fume emission standards (GWPB5-2000)" stipulates that this standard adopts the following definitions

1. Standard state refers to the temperature of 273K, the pressure of 101,325 Pa when the state. The concentration of standard values specified in this standard are the standard state of dry flue gas values.

2. Oil smoke refers to the food cooking, processing volatile oil, organic matter and its heating decomposition or cracking products, collectively known as oil smoke.

3. City The same definition of city as in the Urban Planning Law of the People's Republic of China, i.e., municipalities, cities and towns established by the state in accordance with its administrative structure.

4. Catering unit All smoke exhausting stoves located in the same building and belonging to the same legal person are counted as one catering unit.

5. Unorganized Emission Emission of oil smoke without any oil smoke purification facilities.

6. Oily Smoke Removal Efficiency Refers to the percentage of the mass of oily smoke removed after treatment by the purification facilities and the mass of oily smoke before purification.

The formula: P - oil smoke removal efficiency, %;

c before - the concentration of oil smoke before the treatment facility, mg/m3;

Q before - - exhaust air volume before treatment facility, m3/h;

c after - concentration of oily smoke after treatment facility, mg/m3;

Q after - exhaust air volume after treatment facility, m3/h;