After obtaining the cross-sectional area of the air duct, the size and cross-sectional area of the air duct should be equal, but it should be noted that it should be a net area, and the width-height ratio of the rectangular air duct should be controlled not to be greater than 4, and it should be arranged in combination with the building space.

Is there any restriction on the location of the air duct (generally, the functional layout of the plane will be considered first, and then some corners that are not conducive to the functional layout of the building will be brought to the equipment specialty)? If there are certain restrictions, the restricted parts should be considered first (for example, the length or width may be limited). Generally, it is better to lay the air duct in a long position and attach it to the main body of the structure.

Extended information:

The smoke exhaust duct should not cross the horizontal fire zone. When two fire zones * * * use a smoke exhaust system, the smoke exhaust fan room should be located at the adjacent firewalls of the two fire zones, so as to ensure that the air duct that needs to pass through the firewall but is still in the fire zone is as short as possible, and smoke exhaust fire dampers should be set and corresponding fire prevention measures should be taken. The vertical air duct that vertically passes through each floor should be located in the pipeline well or adopt concrete air duct.

for the smoke exhaust system with two or more smoke prevention zones, a branch pipe should be set to exhaust smoke from each smoke prevention zone, and a smoke exhaust fire valve that can automatically close at 281oC should be set on the branch pipe. For example, in a building with no partition wall in the middle of a large bay, when the ceiling is provided with a deep beam with a clear height of more than 1.5m to divide the smoke-proof zones, a branch pipe should be set on the main air duct under the beam to exhaust smoke from each smoke-proof zone, which can technically solve the problem of setting the smoke outlet.

Baidu Encyclopedia-Exhaust Fan

Optimized design of basement air duct of China Zhiwang-Guomai Building.