Which option is not a sprinkler head type but a standard for installation?

• A. Water meters
• B. Frame arms
• C. Bulb-type sprinklers
• D. NFPA 13

Answer: (D)

Understanding this question comes down to telling apart sprinkler head designs from the installation standard. A sprinkler head type describes the physical head itself, like bulb-type sprinklers. Frame arms are part of the mounting hardware that supports a sprinkler head, not a distinct head style. Water meters are devices used to measure water flow, not sprinkler head designs or installation standards. NFPA 13, on the other hand, is the installation standard that covers how sprinkler systems should be installed, including spacing, supports, and mounting requirements. It is a standard, not a sprinkler head design. So the option that is not a sprinkler head type but a standard for installation is NFPA 13.