Principles and Usage Methods of Thermal Ball Anemometers
1. Construction principle
It is an instrument capable of measuring low wind speeds, with a measurement range of 0.05-10m/s. It consists of two parts: a hot ball measuring rod probe and a measuring instrument. The probe has a glass ball with a diameter of 0.6mm, which is wrapped with a nickel chromium wire coil for heating the glass ball and two thermocouples connected in series. The cold end of the thermocouple is connected to a phosphor copper pillar and directly exposed to the airflow. When a certain amount of current passes through the heating coil, the temperature of the glass ball increases. The degree of increase is related to wind speed, and the degree of increase is greater when the wind speed is low; On the contrary, the degree of increase is small. The magnitude of the increase is indicated on the electricity meter through a thermocouple. Based on the reading of the electricity meter, check the calibration curve to determine the wind speed (m/s).
2. Instructions for use
① Before use, observe whether the pointer of the electric meter points to zero. If there is any deviation, gently adjust the mechanical adjustment screw of the electric meter to make the pointer return to zero;
② Place the calibration switch in the off position;
③ Insert the measuring rod plug into the socket, place the measuring rod vertically upwards, tighten the screw plug to seal the probe, place the "calibration switch" in the full position, slowly adjust the "full adjustment" knob to make the meter pointer point to the full position;
④ Place the "calibration switch" in the "zero position" and slowly adjust the "coarse adjustment" and "fine adjustment" knobs to make the meter pointer point to the zero position;
⑤ After the above steps, gently pull the screw plug to expose the probe of the measuring rod (the length can be selected according to needs), and make the red dot on the probe face the wind direction. Based on the reading of the electric meter, refer to the calibration curve to find out the measured wind speed;
⑥ After measuring for several minutes (about 10 minutes), steps ③ and ④ above must be repeated once to standardize the current inside the instrument;
⑦ After the test is completed, the "calibration switch" should be placed in the off position.
