How to Buy Waterproof Cooling Fan?

For "Waterproof Cooling Fan", designed to be in when we have to consider many aspects, first of all, designed to be the time to consider a two-speed engine, so as to ensure normal operation, but also to ensure that the motor at a low speed and consider whether the noise level to be accepted, to which consumers buy, you need to consider the various factors.
"Waterproof Cooling Fan" variety, I can be the static pressure, air flow and some general properties have to choose the most suitable ventilation and cooling equipment. You can calculate the required power under consideration was for the purpose of motor usage, leaving part of the space.
"Waterproof Cooling Fan" blower was running resistance curve point is the intersection with the characteristic curve, the resistance curve is not moving the air volume. When the resistance curve, the wind changed little. Therefore, if you need two machines running in parallel, must be redesigned too thick pipes, in order to achieve the amount of wind resistance curve and reach.