How many colors are there for sign safety?

1. Red: Used to mark prohibition, stop and fire protection. For example, signal lights, signal flags, emergency stop buttons on machines, etc. all use red to express "forbidden" information.

2. Yellow: used to mark danger. Such as "beware of electric shock", "pay attention to safety", etc.

3. Green: Used to indicate that it is safe and sound. Such as "work here", "grounded", etc.

4. Blue: used to mark enforcement, such as "must wear a safety helmet", etc.

5. Black: geometric figures used to mark images, text and warning signs. According to regulations, in order to facilitate identification, prevent misoperation, and ensure the safety of operation and maintenance personnel, different colors are used to distinguish equipment characteristics.