厨房排烟管道的水平部分不应太长。一般来说，最大距离不应超过15米，坡度应大于2％。水平端应配备接头，以便清洁油污。根据规范，排风速度不得低于10m/s，以防止风速过低时油污附着在烟道上，接集烟罩的排烟管道应设风量调节阀。
The horizontal part of the kitchen exhaust pipe should not be too long. In general, the maximum distance should not exceed 15 meters and the slope should be more than 2%. Joints shall be provided at the horizontal end for cleaning oil. According to the specification, the exhaust speed shall not be less than 10m / s to prevent oil from adhering to the flue when the wind speed is too low. The exhaust pipe connected to the smoke hood shall be equipped with an air volume regulating valve.
排烟管道的设计和安装如果不合理，往往会造成厨房排烟不通畅，直接影响油烟净化器的使用。其主要原因有以下几种：
If the design and installation of smoke exhaust pipe is not reasonable, it will often cause the kitchen smoke is not smooth, which directly affects the use of fume purifier. The main reasons are as follows:
（1）主排烟管通风面积不足，风速过大。根据工程经验，主排烟管的风速不应超过15m/s。否则，经过一段时间的运行（例如一年后），很容易使排烟系统不通畅。在油烟净化器的操作实践中，大多数情况是由于排烟管通风面积不足引起的，并且管内气体的流速高于15m/s。
(1) The ventilation area of the main exhaust pipe is insufficient and the wind speed is too high. According to the engineering experience, the wind speed of the main exhaust pipe shall not exceed 15m / s. Otherwise, after a period of operation (for example, one year later), it is easy to make the smoke exhaust system blocked. In the operation practice of the oil fume purifier, most of the cases are caused by the insufficient ventilation area of the exhaust pipe, and the gas flow rate in the pipe is higher than 15m / s.
（2）由于排烟管穿过建筑梁，管道的横截面积减小，截面的阻力增大，导致气流不畅。
(2) As the smoke exhaust pipe passes through the building beam, the cross-sectional area of the pipe decreases, and the resistance of the cross-section increases, resulting in poor air flow.
（3）当排烟管穿过建筑梁或避开其他设备管道时，排烟管的一部分将低于整个排烟管平面。使用一段时间后，油水混合物将积聚在下排烟管中，直接影响油烟排出。
(3) When the smoke exhaust pipe passes through the building beam or avoids other equipment pipes, part of the smoke exhaust pipe will be lower than the whole smoke exhaust pipe plane. After using for a period of time, the oil-water mixture will accumulate in the lower exhaust pipe, which will directly affect the exhaust of oil smoke.