Suction fan is to use air convection, the principle of negative pressure ventilation design of negative pressure fan installed in a poorly ventilated place, normal work, using negative pressure workshop heat, peculiar smell, lampblack, standing still in the shortest amount of when quickly ruled out outside, at the same time bring fresh air into the indoor, outdoor and rapidly pull in the indoor air, so as to achieve the purpose of ventilation and cooling to improve the workshop environment the