"Exhaust Fan" type more, we need to air flow, static pressure and other attributes to choose the most suitable ventilation and cooling equipment. Computing power required, taking into account the usage of the motor for this purpose, it is best to stay out of the 20-25% margin. When two parallel operating blower A has become equal to the pressure point and the amount of air. Thus, "Exhaust Fan" according FanA, FanB respective curves plotted be resistance, can be run in parallel characteristic curve. Because the blower operating point is the resistance curve with a curve intersection, look for resistance song does not move the air volume. When the resistance curve, substantially increasing the amount of wind. However, no matter what, two blowers in parallel operation are lower than the sum of their capabilities. Thus, "Exhaust Fan" If you really need two machines running in parallel, we need to re-design the thick pipe resistance curve must be done to reach the sum of its air volume.