The difference between the role of exhaust fan exhaust fan and positive pressure fans is this: When the basement fire, there is a lot of smoke produced, this time, the fire started with the exhaust fan, exhaust fan manufacturers, the smoke from the fire area to exclude . In addition, professional production exhaust fan, exhaust fan in the basement can be used as usual but also for air. Positive pressure blower is pointing escape corridor air supply fan. It outdoor air pressure into the interior. When the building is on fire, it will produce a lot of smoke, carbon monoxide and other toxic gases and block the line of sight, exhaust fan supply, through positive pressure blower air to escape the fire stairs, indoor smoke can not reach the stairs, to create conditions for people to escape . If the blower is located in the roof of high-rise buildings, sending through the pipeline to the stairwell or elevator shaft front room fan, then, exhaust fan, known as positive pressure air supply, its role is to fire at the floor, stairwell or elevator to the front compartment blower, guarantor of safe evacuation. II: calculate the required static pressure fan duct according to the situation: 1, based on the amount of wind and wind speed (wind speed 10-15 m / s or so) to determine the cross-sectional area of ??the duct. Duct aspect ratio should not exceed 2: 1 (to save material and reduce the drag). 2, according to the wind speed, the wind pipe cross-sectional area, elbows, reducers, etc. to calculate the drag (ie the required fan static pressure). Three: calculated based on air flow, static pressure. Select the appropriate fan. Sheng clean air conditioning (Figure), roof exhaust fan, exhaust fan from the Texas Air Conditioning Equipment Co., Ltd. Sheng-purification provided. Texas Air Conditioning Equipment Co., Ltd. Sheng-purification (www.dzhffj.com) located in Dezhou City, Shandong Province, Wuhan City acres of industrial park. Scraps and development in the wave of market economy, the current clean air conditioning Sheng Tong has a high profile in fan, ventilation equipment, and enjoys a good reputation. Sheng purification of air conditioning made the whole network business alliance certification, marking our service and management level has reached a new height. Sheng clean air-conditioning staff willing to work with all people of insight and common development, for a better future.