The horizontal section of the kitchen exhaust duct should not be too long. Generally, the farthest horizontal distance should not exceed 15m and there should be a slope of more than 2%. A movable joint should be set at the horizontal end to facilitate the cleaning of oil stains. The exhaust speed shall not be less than 10m/s according to regulations to prevent oil from adhering to the flue due to low wind speed. The branch pipe connected to the exhaust hood should be equipped with an air volume regulating valve.

91影视在线污污污91在线视频观看的设计和安装不合理，往往会造成厨房91影视在线污污污不通畅，直接影响油烟净化器的使用。其主要原因有以下几种：

The design and installation of smoke exhaust ducts are unreasonable, often resulting in poor ventilation of kitchen smoke, directly affecting the use of oil fume purifiers. The main reasons for this are as follows:

（1）主91影视在线污污污91在线视频观看通风面积不够，气体流速过大。根据工程经验，91影视在线污污污主91在线视频观看内风速不能超过15m/s。否则在运行一个时期以后（如一年以后）很容易造成91影视在线污污污系统不通畅。在油烟净化器的运行实践中，大部分案例都是因91影视在线污污污91在线视频观看通风面积不足引起的不通畅，91在线视频观看内气体的流速都在15m/s以上。

(1) The ventilation area of the main smoke exhaust duct is insufficient, and the gas flow rate is too high. According to engineering experience, the wind speed inside the smoke exhaust main duct cannot exceed 15m/s. Otherwise, after a certain period of operation (such as one year later), it is easy to cause the smoke exhaust system to be blocked. In the operation practice of oil fume purifiers, most cases are caused by insufficient ventilation area of smoke exhaust pipes, resulting in blockage. The gas flow rate in the pipes is above 15m/s.

（2）91影视在线污污污91在线视频观看由于要穿过建筑梁而使91在线视频观看通风截面积变小，截面上阻力增加，造成气流不通畅。

(2) Due to the need to pass through the building beam, the ventilation cross-sectional area of the smoke exhaust duct decreases, resulting in increased resistance on the cross-sectional area and obstructed airflow.

（3）91影视在线污污污91在线视频观看在穿过建筑梁或躲避其它设备91在线视频观看时，91影视在线污污污91在线视频观看中的一段会低于整体91影视在线污污污91在线视频观看平面。在使用一段时间后，由于油水混合物会积聚在较低的那段91影视在线污污污91在线视频观看中，直接影响91影视在线污污污通畅。

(3) When passing through building beams or avoiding other equipment pipelines, a section of the smoke exhaust pipeline will be lower than the overall plane of the smoke exhaust pipeline. After a period of use, the oil-water mixture will accumulate in the lower section of the smoke exhaust duct, directly affecting the smoothness of smoke exhaust.

（4）不同楼层的厨房油烟通过同一主91在线视频观看排出，离出口近的楼层厨房91影视在线污污污效果较好，而较低楼层的厨房91影视在线污污污不通畅。

(4) Kitchen oil fumes from different floors are discharged through the same main pipeline. The kitchens near the exit have better smoke exhaust effect, while the kitchens on lower floors have poor smoke exhaust.

常用的91影视在线污污污风机有轴流风机、风机箱和离心风机3种。

There are three commonly used smoke exhaust fans: axial flow fan, fan box, and centrifugal fan.

（1）轴流风机以前应用较多，但由于全压小，在安装油烟净化器后很少应用。

(1) Axial flow fans were previously widely used, but due to their low total pressure, they were rarely used after installing oil fume purifiers.

（2）风机箱全压中等，风量可以调节，且噪声较低，常在集烟罩距油烟排放口距离中等的厨房91影视在线污污污系统中选用。

(2) The fan box has a moderate total pressure, adjustable air volume, and low noise. It is often used in kitchen smoke exhaust systems where the distance between the hood and the oil fume discharge outlet is moderate.

（3）离心风机全压和风量都可以调节，但由于噪声较大，常需要做降噪处理。当厨房位于建筑物的底部时其排风机宜安放在屋顶，一方面可减少室内噪声污染，同时排风风道处于负压状态，可避免气味外溢。风机安放在屋顶时，一般选择离心风机。

(3) The total pressure and air volume of the centrifugal fan can be adjusted, but due to the high noise, noise reduction treatment is often required. When the kitchen is located at the bottom of the building, its exhaust fan should be placed on the roof to reduce indoor noise pollution, and the exhaust duct should be in a negative pressure state to avoid odor leakage. When placing fans on the roof, centrifugal fans are generally chosen.