Color is the secondary means to identify the contents of a piping system but, many times the most important.
The color of the marker should be used to identify the characteristic hazard of the contents of the pipe.
Install duct markers with permanent adhesive on air ducts in the following color codes:
- Green: For cold-air supply ducts.
- Yellow: For hot-air supply ducts.
- Blue: For exhaust-, outside-, relief-, return-, and mixed-air ducts.