What is the minimum exposed barrel length for a dry sprinkler barrel exposed to 50°F...

For dry sprinklers, the exposed barrel length must be sufficient to prevent freezing. In extreme temperature differentials, such as from 50°F to -30°F, a longer barrel length, such as 18 inches, may be required to ensure the sprinkler remains functional.

References: NFPA 13 guidelines for the installation of dry sprinklers, considering the insulation and barrel length requirements to prevent freezing in cold environments.