Because the air duct heater is mainly used in industry, in general, according to the temperature requirements, air volume requirements, size, material and so on, the final selection is not the same, and the price is different. In general, the selection can be in accordance with the following 5 points:
First, power selection
The selection of power is to meet the heat required by the heating medium, is to ensure that the heater can achieve the purpose of heating, normal operation of the choice.
Power calculation should consider the following three options:
(1) From the initial state, according to the specified time requirements to achieve the heating medium to the set temperature < working temperature);
(2) under working conditions, the calorific value is enough to maintain the temperature of the medium;
(3) There should be a certain safety margin, generally 1.2.
Obviously, the greater the power selected from Article (1) (2), multiplied by the safety margin is the selected power.
Two, wind speed design
The measurement of wind pressure, wind speed and air volume of duct can be completed by pitot tube, U-type manometer, tilted micromanometer, 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. The measured total pressure can know the working condition of the fan and the resistance of the ventilation system. The air volume of the duct can be converted from the measured dynamic pressure of the duct. The wind speed in the duct can also be measured directly with the hot ball anemometer, and the air volume in the duct can be converted from the wind speed.
1. Connect the fan and ventilation duct
2. Use steel coil to detect the diameter of the air duct or the size of the rectangular air duct
3. according to the diameter or rectangular duct size, determine the location of the measuring point
4. Open a round hole with a diameter of 12mm on the air duct at the test position
5. Mark the location of the measuring point on the pitot tube or hot ball anemometer
6. Pitot tube and U-type manometer are connected 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 must be correct, and pay attention to the direction of the 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.
