wiff 门铃

Exhaust fan, also known as negative pressure fan, negative pressure fan. Is the use of air convection can make the room has been in a negative pressure state, forming a suction, an endless stream of outdoor air, and vent the indoor hot air, so as to achieve ventilation and cooling effect.
classification
According to the intake and exhaust points
The exhaust fan is divided into a partition wall type according to the intake and exhaust ports (both sides of the partition hole are free spaces, and the air is exhausted from one side to the other side of the partition wall) Gas, and the other side of the exhaust through the catheter), the catheter into the gas type (one side of the air through the catheter, while the other side of the free space to exhaust), all catheter type (exhaust fans are placed on both sides of the catheter, Intake and exhaust). (Air from parallel to the direction of rotation axis perpendicular to the axis of the discharge), axial flow (air parallel to the direction of rotation from the axis into the axis is still parallel to the direction of discharge) and cross-flow (Air entering and discharging is perpendicular to the direction of the axis).
According to ventilation mode points
Exhaust fan ventilation mode is discharged, inhalation, and use three. Dust-out type from the natural air intake into the air, exhaust air through the exhaust fan; inhalation through the ventilation fan inhaled fresh air from the natural exhaust port discharge of dirty air; and use the type of suction and exhaust by the exhaust fan to complete.