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DC Fire Sprinkler study materials
DC Fire Sprinkler study resources

DC Fire Sprinkler: Fire Sprinkler System Components and Materials

DC Fire Sprinkler · Work through your exam, one topic at a time.

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Fire Sprinkler System Components and Materials

Component questions test whether you can pick the right device for the hazard and environment, and whether you know what is listed for fire service. Expect identification-style items on sprinkler types, temperature ratings, K-factors, valves, pipe, joining methods, hangers and alarm trim.

Sprinklers

  • Pendent, upright, sidewall, concealed and recessed standard-spray heads.
  • Special types: ESFR (early suppression fast response), CMSA (control mode specific application), residential, and extended-coverage heads. ESFR heads are for high-piled storage; their listing controls spacing, ceiling height and clearance.
  • Temperature ratings follow the color code: 135–170°F uncolored or black, 175–225°F white, 250–300°F blue, 325–375°F red, 400–475°F green, 500–575°F orange.
  • The K-factor is the discharge coefficient in Q = K√P. Common values are 5.6 (1/2 in.), 8.0 (17/32 in.), 11.2 (3/4 in.), 14.0, 16.8, 22.4 and 25.2 for ESFR.

Valves, pipe and trim

  • Indicating valves (OS&Y, post indicator, butterfly with tamper switch) show open or closed at a glance; non-indicating valves (check, dry-pipe, deluge, preaction) do not.
  • A backflow preventer protects the public supply; the water authority and plumbing code set the approved assembly and testing.
  • Black steel Schedule 40 or Schedule 10 is standard; galvanized, copper, stainless and listed CPVC appear where listings allow. Joining: threaded, grooved, welded, brazed, cemented (CPVC).
  • Each system needs a main drain, flow switch, inspector's test connection, valve trim and a spare sprinkler cabinet with wrench: 6 spares up to 300 heads, 12 for 301–1,000, 24 above 1,000.

Worked example

An ESFR head with K = 25.2 is supplied at 50 psi. Flow = 25.2 × √50 = 25.2 × 7.07 = 178 gpm. A K = 5.6 head at the same pressure gives 5.6 × 7.07 = 39.6 gpm. The K-factor changes flow far more than a modest pressure change, which is why the hydraulic calculation follows the listing rather than a rule of thumb.

Traps

Mixing up K-factor with orifice diameter; specifying a 165°F head where ambient temperature crowds the rating; substituting non-listed CPVC or fittings; forgetting that ESFR, CMSA and residential heads override the general spacing tables with their own listing rules.