What is the difference between pipe markers and the NFPA diamond?

While NFPA diamonds and pipe markers work to inform employees to be cautious around highly dangerous or hazardous substances, there are a few very distinct differences between the two visual communicators. However, let’s begin with the similarities. Both the NFPA diamonds and pipe markers share the following:

  • They both use colors as a primary source of categorization.
  • They are both placed on objects that contain hazardous substances.
  • They both help emergency responders identify chemicals in the event of an accident.

The differences between the two chemical markers are as follows:

  • The layout
    • NFPA diamonds are divided into four separate diamonds that each denote a specific property of the contained chemical.
    • Pipe markers have a solid rectangular body that allows for easy visibility on a pipe.
  • Colors
    • NFPA diamonds have four primary colors which include red for flammability, blue for health hazard, yellow for instability, and white for any other special properties the chemical may have.
    • Pipe markers also go by a color scheme, but they generally only have one color that categorizes the contained chemical.
  • The type of information
    • NFPA diamonds are generally more specific in regard to hazard levels than pipe markers. Each colored diamond contains a number 1-4 that corresponds with how dangerous that substance is regarding its flammability, reactivity, and negative health effects.
    • Pipe markers only have the name of the chemical or substance, the categorization of its properties by color, and the flow direction.
  • Label location
    • NFPA diamonds are generally placed on objects used for transporting dangerous chemicals as well as storage tanks.
    • Pipe markers are solely seen on pipes that are used to transport substances within a building or at other industrial locations.
  • Regulations and standards
    • OSHA permits the use of NFPA diamonds as long as the information doesn’t conflict with their regulation known as the Hazard Communication Standard.
    • Pipe markers must follow the ANSI and ASME’s A13.1 standard which has been incorporated by reference into OSHA’s pipe marking regulations. Companies are obligated to follow these safety regulations.

Overall, both NFPA diamonds and pipe markers vary in the information they give to employees. However, the end goal is the same—to keep employees safe from harm while on the job.


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