1. exhaust pipe: a vertical exhaust pipe assembled by closed L-shaped members and internal corner walls or overlapping finished pipes.

2. Wind hood: negative pressure wind hood or degassing wind hood is installed at the outlet end of the roof exhaust duct one by one to prevent wind, rain and snow from flowing backwards, and the exhaust system can be degassed by natural wind.

3. Valves: variable pressure-five anti-extraction valves are installed at the air inlet of the exhaust pipeline one by one and connected with the outlet of the range hood or exhaust fan through hoses.

4. Fan: kitchen range hood or toilet exhaust fan-mechanical equipment that absorbs and exhausts indoor smoke and polluted air. The system works through a fan, which sends kitchen fume or polluted air in the bathroom into the variable-pressure five-anti-extraction valve, enters the exhaust duct, and is exhausted by the range hood. The system forms the working principle of gas extraction through the conversion of dynamic pressure and static pressure in liquid expressed by Bernoulli equation of aerodynamics:

1), the ascending air flow in the exhaust pipe enters the variable pressure area in the variable pressure extraction valve to produce jet, which reduces the negative pressure or static pressure at the air inlet;

2) mechanically pumping airflow into the gas extraction area in the variable pressure gas extraction valve to generate upward jet to extract gas from the lower end;

3) Outdoor natural wind enters the jet plate of the range hood to generate jet to pump air into the system.