1. Indoor installation or protective mode outdoor applications;

2. Outdoor open-air device, wind, sand, rain dew, sunlight and other erosion;

3. Have flammable, explosive gas or dust environment;

4. Wet and hot zone, dry tropical environment;

5. Pipeline medium temperature of up to 450 ℃;

6. Ambient temperature below-20 ℃;

7. Vulnerable to flooding or immersion;

8. Environment with radioactive substances (nuclear power plants and radioactive material test devices);

9. An environment on a ship or dock wharf (with salt mist, mold, moisture); 10. An occasion with severe vibration; an occasion prone to fire;