MD Fire Sprinkler cheat sheet

Light hazard density starts at 0.10 gpm/ft² over 1,500 ft²; Ordinary Group 1 at 0.15 gpm/ft² over 1,500 ft²; Ordinary Group 2 at 0.20 gpm/ft² over 1,500 ft².

Extra Hazard Group 1: 0.30 gpm/ft² over 2,500 ft²; Extra Hazard Group 2: 0.40 gpm/ft² over 2,500 ft² - densities and areas are the baseline before any adjustments.

Design area may be reduced 25% when a full-height, noncombustible draft curtain encloses the area and sprinklers are spaced 12 ft or less, with at least one sprinkler on each side of the curtain.

Wet-pipe design area may be reduced 30% when the ceiling height exceeds 20 ft and the system is hydraulically calculated, using the NFPA 13 height-versus-density curve.

Quick-response sprinklers in wet systems permit design area reduction to 75% of standard (Light/Ordinary) when ceiling height is 10 ft or less, with further reduction to 50% at heights above 10 ft up to 20 ft.

Dry-pipe and double-interlock preaction systems increase the design area by 30% (single-interlock preaction uses the wet-pipe area) to compensate for the larger volume of gas to be expelled.

Sloped ceilings: sprinklers spaced along the slope with the branch line perpendicular to the ridge; design area increase applies where slope exceeds 2 in 12 on dry systems.

K-factor relates flow and pressure: Q = K√P, so a K-5.6 sprinkler at 7 psi flows about 14.8 gpm; higher K-factors deliver the same density at lower pressure.

Hydraulic calculation uses Hazen-Williams: friction loss per foot = 4.52 Q^1.85 / (C^1.85 d^4.87), with C=120 for black steel and C=150 for cement-lined or plastic pipe.

Branch line spacing maximums: Light hazard 15 ft, Ordinary hazard 15 ft, Extra hazard 12 ft; the maximum protection area per sprinkler is 225 ft² (Light), 130 ft² (Ordinary), and 100 ft² (Extra Hazard).

Sprinklers must be at least 4 in from a wall and no more than half the allowable spacing from a wall; the distance from the deflector to the ceiling is 1 in minimum to 12 in maximum for standard spray uprights and pendents.

Pendent and upright sprinklers must be installed with the deflector parallel to the ceiling/slope; sidewall sprinklers require the deflector 4 in to 6 in below the ceiling with a maximum 15 ft spacing and 196 ft² area.

Hanger spacing: 1 in pipe every 12 ft, 1¼ in every 15 ft, 1½ in every 15 ft, 2 in and larger every 12 ft; the first hanger is within 12 in of the sprinkler on a branch line.

Sway bracing is required for all pipe 2½ in and larger, at intervals not exceeding 40 ft, and at the top of risers and at changes in direction; flexible couplings are used at the building seismic joint.

Underground lead-in must be at least 4 in diameter for a riser serving more than one sprinkler, with a gate valve and a check valve in the riser assembly and a test valve at the remote end.

The riser must include a main drain sized to the largest riser, a gauge on the supply side and system side, an alarm check valve or wet alarm valve, and a flow switch on the riser.

Pipe must be supported so that it does not rest on ceiling tiles or suspended ceiling grids; sprinkler drops must be protected by an escutcheon, and pipe must not be used to support other loads.

Hydrostatic test: 200 psi for two hours for systems rated at 150 psi or less, or 50 psi above working pressure when working pressure exceeds 150 psi; test the entire system before concealment.

Weekly: inspect gauges on wet systems; monthly: inspect alarm valves, gauge readings, and dry-pipe valve conditions; quarterly: test waterflow alarm devices and check valve position.

Annual: main drain flow test on wet systems, dry-pipe valve trip test, antifreeze solution concentration check, and inspection of all sprinklers for corrosion, paint, or damage.

Every five years: internal inspection of the dry-pipe valve and the water supply piping; every three years: replace dry-pipe valve internal parts and test the water supply for bacterial activity.

Sprinkler replacement schedule: fast-response sprinklers at 20 years, standard-response at 50 years, and any sprinkler showing corrosion, paint, or physical damage immediately.

Main drain test records the static and residual pressure; a drop of more than 10% in residual pressure compared with the previous test indicates a supply problem requiring investigation.

Flow test at the inspector's test connection must produce an alarm within 90 seconds for wet systems; for dry systems, the alarm must sound within 90 seconds after the valve trips.

Gauge accuracy is verified every five years by comparing to a calibrated gauge; gauges must be replaced if the reading differs by more than 5% or if the gauge is damaged.

Impairment procedure: notify the fire department and building occupants, post the system out of service, provide a fire watch if the system is out of service more than 4 hours, and document restoration.

Maryland adopts NFPA 13 (installation), NFPA 13R (residential up to four stories), NFPA 13D (one- and two-family dwellings), and NFPA 25 (ITM) through the Maryland Building Performance Standards and the State Fire Prevention Code.

The Maryland State Fire Marshal regulates sprinkler installation, alteration, and maintenance; a permit from the State Fire Marshal is required before work begins.

Sprinkler contractor licensing is administered under the Maryland Business Occupations and Professions Article; the license is issued by the State Fire Marshal's office and requires a qualifying agent.

Maryland requires sprinkler protection in new one- and two-family dwellings and townhouses under the State Fire Prevention Code, with local jurisdictions permitted to adopt more stringent requirements.

Plan review and inspection fees are set by the State Fire Marshal; inspections must occur at rough-in, before concealment, and at final completion.

Maryland's fire code incorporates NFPA 1 and the International Fire Code; where the two conflict, the more stringent provision applies.

High-rise buildings (over 75 ft) in Maryland require automatic sprinkler protection throughout, plus a fire command center and standby power for fire pumps.

The State Fire Marshal may accept alternative methods or materials with a written request and supporting documentation; approval must be obtained before installation.

Plan submittal must include hydraulic calculations, sprinkler layout, pipe sizing, hanger and bracing details, water supply test data, and manufacturer's product data sheets.

Water supply test data must be no more than 12 months old and must show static pressure, residual pressure, and flow at the test hydrant, with the test location identified on the plan.

The plan reviewer checks that the design density and area match the hazard classification, that sprinkler spacing and coverage comply with NFPA 13, and that the hydraulic calculation is balanced.

A licensed sprinkler contractor's qualifying agent must be identified on the permit application; the license number and expiration date must appear on the submittal.

Plan review approval expires if work does not begin within 12 months; the permit may be extended once for an additional 12 months upon written request.

As-built drawings reflecting any field changes must be submitted at completion; the State Fire Marshal may require a new plan review if changes affect hydraulic performance.

Inspector qualifications: the individual performing acceptance testing must hold a Maryland sprinkler contractor license or work under the direct supervision of a licensed contractor.

Final acceptance requires the contractor's material and test certificate (NFPA 13 Figure A.28.1), hydrostatic test records, and a completed NFPA 25 baseline inspection report.