How to use an anemometer to measure air volume and wind speed
An anemometer is an instrument that measures air velocity. There are many types of it, and the wind cup anemometer is commonly used in meteorological stations. It consists of three parabolic cone empty cups fixed on the bracket at 120° to each other to form the sensing part. The concave surfaces of the empty cups are all in one direction. The whole induction part is installed on a vertical rotating shaft, and under the action of wind force, the wind cup rotates around the shaft at a speed proportional to the wind speed. How should the user use the anemometer to measure the air volume and wind speed?
A. Air volume and wind speed detection must be carried out first. All purification effects are obtained under the designed air volume and wind speed.
B. Before testing, check whether the fan is operating normally. The size of the air outlet and air duct to be tested must be measured on the spot.
C. For a unidirectional flow (laminar flow) clean room, the air volume is determined by the product of the average wind speed of the room section and the product of the clean area.
(Take the section 0.3m away from the high-efficiency filter perpendicular to the airflow as the sampling section, and set no less than 5 test points on the section according to the distance between the test points should not be greater than 0.6m, and the arithmetic mean of all readings is taken as the average wind speed.) Vertical The measurement section of the unidirectional flow (laminar flow) clean room is based on the horizontal section of the ground from 0.8m to 1m; the measurement section of the horizontal unidirectional flow (laminar flow) clean room is based on the vertical section of the air supply surface from 0.5m to 1m; The number of upper test points should not be less than 10, and the spacing should not be greater than 2m, and they should be evenly arranged;
D. For the tuyere equipped with a filter, the air volume is determined by the product of the average wind speed of the tuyere section and the net cross-sectional area of the tuyere. (The average wind speed can be obtained from not less than 6 uniformly arranged test points on the section of the tuyere or the section referencing the auxiliary air duct.)
E. When there is a long branch pipe section on the windward side of the tuyere and holes have been or can be drilled, the air volume can be determined by the air duct method. (Drill holes not less than 3 times the pipe diameter or 3 times the length of the large side before the air outlet;)
F. For rectangular air ducts, divide the measured section into several equal small sections, each small section is as close to a square as possible, the side length is not more than 200mm, the test point is located in the center of the small section, but the entire section should not be less than 3 tests points; for circular air ducts, the measuring section should be divided according to the equal-area circular method and the number of test points should be determined; holes should be opened on the outer wall of the air duct, and thermal anemometer probes or pitot tubes should be inserted. (Converted to air volume by measuring dynamic pressure.)
