Comprehensive and Detailed Step-by-Step Explanation:
Flow Testing for Piping:
According to NFPA 25 (Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems), Section 14.2.1, underground and exposed piping must be flow tested at least once every 5 years.
This ensures the internal condition of the piping is adequate and free from obstructions, corrosion, or deposits that could affect water flow.
Why Every 5 Years is Required:
Over time, buildup or deterioration within the piping can restrict water flow, impacting the performance of the fire protection system.
Regular testing helps identify and address issues before they compromise fire safety.
Other Options Explained:
Option B (Every 6 years), Option C (Every 10 years), Option D (Every 20 years): These intervals do not meet the minimum requirements established in NFPA 25.
Summary:
Flow testing of underground and exposed piping must be conducted once every 5 years to ensure their internal condition meets fire protection standards.