Use in air: 1. Closed air heating
2. Circulating air heating
3. Special gas heating
Use in liquids: 1. Heating in water
2. Heating in oil
3. Acid-base liquid heating (heating tube heating zone should be immersed in the air can not be exposed)
The watt density and material used are different and should not be confused. The good use environment should not produce skin, thin, dust, oil, water and so on.