High efficiency air filter wind speed, rated air flow, resistance, efficiency must be in the test stand around the frame does not leak, the tightness must be strict, otherwise it will affect the accuracy of the test data and authenticity. The air resistance of the filter under the rated air flow is the initial resistance. The surface wind speed is affected by its resistance. The larger the resistance is, the larger the wind speed is, and the air volume and resistance are proportional to each other.