Because the air duct heater is mainly used in industry. According to the temperature requirements, air volume requirements, size, material and so on, the final selection will be different, and the price will also be different. In general, the selection can be made according to the following two points:
The correct selection of wattage can meet the energy which is required by heating medium, ensure that the heater can reach the required temperaturw when operating. Then, the following three aspects should be considered on wattage calculation selection:
(1) Heat the heating medium from the initial temperature to set temperature within specified time;
(2) under working conditions, the energy should be enough to maintain the temperature of the medium;
(3) There should be a certain safe margin, generally it should be 120%.
Obviously, the larger wattage is selected from (1) and (2), and then, the selected wattage is multiplied by the safe margin.
2. Design value of wind speed :
The measurement of wind pressure, wind speed and air volume can be accomplished by pitot tube, U-type manometer, tilting micro-manometer, hot ball anemometer and other instruments. Pitot tube and U-type manometer can test the total pressure, dynamic pressure and static pressure in the air duct heater, and the working condition of the blower and the resistance of the ventilation system can be known by the measured total pressure. The air volume can be converted from the measured dynamic pressure. We can also measure the wind speed with the hot ball anemometer, and then get the air volume accoring to the wind speed.
1. Connect the fan and ventilation pipe;
2. Use a steel tape to measure the the size of air duct;
3. according to the diameter or rectangular duct size, determine the location of the measuring point;
4. Open a round hole (φ12mm) on the air duct at the test position;
5. Mark the location of measuring points on pitot tube or hot ball anemometer;
6. Connect the picot tube and U-type manometer with latex tube;
7. Pitot tube or hot ball anemometer is vertically inserted into the air duct at the measuring hole, so as to ensure that the position of the measuring point is correct, and pay attention to the direction of pitot tube probe;
8. Read the total pressure, dynamic pressure and static pressure in the duct directly on the U-shaped manometer, and read the wind speed in the duct directly on the hot ball anemometer.
Post time: Nov-12-2022