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Dry pipe sprinkler system maintenance: trip tests, drains, and winter prep

Updated · General information, not legal advice

Dry pipe systems protect unheated areas such as parking garages, loading docks, and attics. They hold air instead of water, so they have more parts to maintain and are prone to corrosion from trapped condensate.

Routine checks

  • Gauges and air pressure: monitored on a regular schedule (monthly in NFPA 25 for dry systems where not supervised).
  • Valve enclosure heat: in freezing weather the dry-pipe valve room must stay above freezing; NFPA 25 calls for daily checks during cold weather unless the enclosure has a low-temperature alarm (then weekly).
  • Quick-opening devices and priming water level: quarterly.

Trip tests

Each year the dry-pipe valve gets a partial-flow trip test. Every three years (and after the system is altered), a full-flow trip test fills the system with water and measures how long water takes to reach the inspector's test connection. Afterward the system must be drained, including all low points, and returned to air.

Low-point drains (auxiliary drains)

Condensate collects in low points and can freeze and crack pipe. Drain them before freezing weather and repeatedly through the winter as needed. Ask your contractor for a list of every auxiliary drain location so building staff can find them.

Signs of trouble

  • The air compressor running often, which can mean leaks.
  • Frequent false trips.
  • Pinhole leaks or rust staining on pipe, often a sign of corrosion.

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Sources

  1. NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems (NFPA)
  2. NFPA 13, Standard for the Installation of Sprinkler Systems (NFPA)

NFPA standards are available to read free online from NFPA. Requirements depend on the edition your jurisdiction adopts; confirm with your authority having jurisdiction.

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