First, the difference is as follows:

1, the purpose is different: the usual purpose of air supply exhaust is to eliminate residual heat, humidity hazardous substances; fire exhaust air supply exhaust purpose is to prevent smoke smoke, smoke that is, to maintain a certain positive pressure in the region to ensure that the requirements can be invasive, smoke is a timely manner to the smoke exhaust to ensure that people evacuate normally;

2, the design of different air speeds: usually open air supply exhaust, taking into account the noise operating costs, control air speed is generally greater than 10m / s. Fire exhaust air supply fire is the start of the fire, the general control of the metal duct air speed shall be greater than 20m / s, the civil construction of the air duct shall be greater than 15m / s;

3, different methods of calculation of air volume: usual air supply exhaust is generally calculated according to the number of air changes, the number of air changes in different rooms is the same, there are also calculated according to the dilution equation. Anti-smoke generally calculated by unit area , the amount of smoke per unit area is the same (basement garage is also calculated by the number of air changes).