The fan must be installed behind the oil smoke purifier, give a simple and clear example of it, you will understand, have seen the doctor with a needle tube? Needle know tube in the process of sucking water is pumping, not laborious, right, if in the water out, is not laborious. Because there is a resistance in the middle, in fact, the fan behind the oil smoke purifier is also the reason, the fan is placed in front of the purifier is to use the thrust to send the smoke to the purifier in order to purify, will be subjected to a great deal of resistance, not enough wind words, the oil will lead to reflux of fumes inside the kitchen is not discharged, all the reasons for the smoke, the fan is placed in the back, the fan's own rotation speed through the fan, the pipeline of the oil smoke through the smoke collection hood downstream to the oil smoke Inside the oil smoke purifier, in the oil smoke purifier to ensure that stays 2 seconds, the particles of oil smoke purification, the other substances through the fan emissions into the atmosphere volatile. This time-saving, normal cycle.