PRELIMINARY: Preliminary sprinkler layout and hydraulic screening, not engineering and not for construction. Heads, pipe sizes and pressures come from simplified rules and configurable default values taken from public summaries of NFPA 13, not from the standard itself; a qualified fire protection designer lays out and calculates the system under the edition the authority having jurisdiction adopts. Outputs are drafts for review by the licensed professional of record.

Hydraulic report, sprinklers in the plenum of the office floor (illustrative model, light hazard, wet pipe)
Computed by node tools/showcase/build.js sprinkler-plenum. Same input, same numbers.

Water supply (an assumption, not a flow test): static 5.5 bar, residual 4.2 bar at 1500 liters per minute. Available pressure at a flow Q: static - (static - residual) x (Q / residual flow)^1.85.

Rooms (each is its own zone, fed from its own riser connection; the margin is the available pressure at the demand flow less the pressure the calculation needs at the riser):
  101 Open office west: 6 heads; most remote area 6 heads, 99.8 m2 (design area 139.4 m2); sprinkler flow 605.0 l/min plus hose stream 378.5 = demand 983.6 l/min (259.8 gpm); needs 3.23 bar at the riser; supply 4.90 bar at that flow; margin 1.68 bar.
  102 Meeting room 1: 4 heads; most remote area 4 heads, 52.6 m2 (design area 139.4 m2); sprinkler flow 280.1 l/min plus hose stream 378.5 = demand 658.6 l/min (174.0 gpm); needs 1.76 bar at the riser; supply 5.22 bar at that flow; margin 3.46 bar.
  103 Meeting room 2: 4 heads; most remote area 4 heads, 48.0 m2 (design area 139.4 m2); sprinkler flow 265.8 l/min plus hose stream 378.5 = demand 644.3 l/min (170.2 gpm); needs 1.52 bar at the riser; supply 5.23 bar at that flow; margin 3.70 bar.
  104 Open office east: 6 heads; most remote area 6 heads, 99.8 m2 (design area 139.4 m2); sprinkler flow 560.1 l/min plus hose stream 378.5 = demand 938.6 l/min (248.0 gpm); needs 3.13 bar at the riser; supply 4.95 bar at that flow; margin 1.83 bar.
  105 Break room: 6 heads; most remote area 6 heads, 99.8 m2 (design area 139.4 m2); sprinkler flow 586.9 l/min plus hose stream 378.5 = demand 965.4 l/min (255.0 gpm); needs 3.49 bar at the riser; supply 4.92 bar at that flow; margin 1.43 bar.

Governing room (smallest margin): 105 Break room. Governing head: 6. Newton iterations: 4.

Most remote area, 105 Break room (flow in l/min, pressure in bar):
  head 1 at x 14.00 y 10.00: area 17.5 m2, flow 140.8, pressure 3.10, required 0.80
  head 2 at x 18.00 y 10.00: area 16.0 m2, flow 122.6, pressure 2.35, required 0.66
  head 3 at x 22.00 y 10.00: area 16.0 m2, flow 90.2, pressure 1.27, required 0.66
  head 4 at x 17.90 y 14.00: area 16.4 m2, flow 81.4, pressure 1.03, required 0.70
  head 5 at x 22.00 y 14.00: area 16.4 m2, flow 80.7, pressure 1.02, required 0.70
  head 6 at x 14.00 y 14.38: area 17.5 m2, flow 71.4, pressure 0.80, required 0.80

Pipes, 105 Break room (bore in mm, length in m, equivalent length in m, flow in l/min, velocity in m/s, friction loss in bar):
  pipe 1: DN50, length 2.68, equivalent 5.68, flow 586.9, velocity 4.98, friction 0.345
  pipe 2: DN25, length 0.08, equivalent 0.57, flow 140.8, velocity 4.78, friction 0.073
  pipe 3: DN40, length 3.87, equivalent 6.27, flow 446.1, velocity 5.92, friction 0.680
  pipe 4: DN40, length 0.38, equivalent 3.98, flow 323.6, velocity 4.29, friction 0.238
  pipe 5: DN25, length 4.35, equivalent 8.10, flow 152.7, velocity 5.19, friction 1.190
  pipe 6: DN25, length 0.08, equivalent 0.57, flow 81.4, velocity 2.76, friction 0.026
  pipe 7: DN25, length 4.36, equivalent 7.35, flow 71.4, velocity 2.42, friction 0.264
  pipe 8: DN25, length 4.00, equivalent 5.25, flow 170.8, velocity 5.80, friction 0.949
  pipe 9: DN25, length 0.08, equivalent 0.57, flow 90.2, velocity 3.06, friction 0.032
  pipe 10: DN25, length 4.08, equivalent 6.32, flow 80.7, velocity 2.74, friction 0.285
  pipe 11: DN25, length 0.20, equivalent 1.45, flow 122.6, velocity 4.16, friction 0.142

Parameters (NFPA 13 values are cited by section and are verified: false, recalled from public summaries; verify them against the edition the authority having jurisdiction adopts):
  maxArea: 20.903 m2 (225 ft2) - NFPA 13 (2019 edition numbering) section 10.2.4.2.1, Table 10.2.4.2.1(a), verified: false
  maxSpacing: 4.572 m (15 ft) - NFPA 13 (2019 edition numbering) section 10.2.5.2, Table 10.2.4.2.1(a), verified: false
  maxWallDistance: 2.286 m (7.5 ft (half the spacing)) - NFPA 13 (2019 edition numbering) section 10.2.5.3, verified: false
  minWallDistance: 0.102 m (4 in) - NFPA 13 (2019 edition numbering) section 10.2.5.4.1, verified: false
  minSpacing: 1.829 m (6 ft) - NFPA 13 (2019 edition numbering) section 10.2.5.4.2, verified: false
  density: 0.0000679 m3/s per m2 (0.10 gpm/ft2 (4.1 mm/min)) - NFPA 13 (2019 edition numbering) section 19.3.3.1.1, Figure 19.3.3.1.1, verified: false
  designArea: 139 m2 (1500 ft2 (139 m2)) - NFPA 13 (2019 edition numbering) section 19.3.3.1.1, Figure 19.3.3.1.1, verified: false
  hoseStream: 0.00631 m3/s (100 gpm, inside and outside hose combined) - NFPA 13 (2019 edition numbering) section 19.3.3.1.2, Table 19.3.3.1.2, verified: false
  minPressure: 48263 Pa (7 psi (0.48 bar)) - NFPA 13 (2019 edition numbering) section 28.2.4.10.1, verified: false
  obstructionFactor: 3 - (3 x the obstruction's width) - NFPA 13 (2019 edition numbering) section 10.2.7.2.1.3 (the "three times rule"), verified: false
  obstructionMaxClear: 0.610 m (24 in) - NFPA 13 (2019 edition numbering) section 10.2.7.2.1.3, verified: false
  wideObstruction: 1.219 m (4 ft) - NFPA 13 (2019 edition numbering) section 10.2.7.2.3, verified: false
  kFactor: 80 - design default (not NFPA 13)
  C: 120 - design default (not NFPA 13)
  deflector: 0.05 - design default (not NFPA 13)
  minDiameter: 0.025 - design default (not NFPA 13)
  maxVelocity: 6 - design default (not NFPA 13)
  elbowLD: 30 - design default (not NFPA 13)
  teeRunLD: 20 - design default (not NFPA 13)
  teeBranchLD: 60 - design default (not NFPA 13)
  temperature: 10 - design default (not NFPA 13)
  minMargin: 0 - design default (not NFPA 13)
  headDiameter: 0.05 - design default (not NFPA 13)
  headHeight: 0.06 - design default (not NFPA 13)
  fixtureClear: 0.15 - design default (not NFPA 13)

Limits of the method:
  - Tree systems only: gridded and looped systems are out of scope.
  - Rectilinear rooms with one flat ceiling; no soffits, sloped ceilings or concealed combustible spaces.
  - Obstructions are boxes: one that crosses a bay cuts it (the beam rule, simplified); any other keeps heads at min(3 x its width, 0.6 m); depth below the deflector is not considered.
  - The design area is the nearest heads to each head; the standard's rectangle along the branch lines is not modelled.
  - The supply curve is taken at the source point; velocity pressure is ignored.
  - Parameter values are recalled from public summaries (verified: false) and must be checked against the adopted edition.

Preliminary sprinkler layout and hydraulic screening, not engineering and not for construction. Heads, pipe sizes and pressures come from simplified rules and configurable default values taken from public summaries of NFPA 13, not from the standard itself; a qualified fire protection designer lays out and calculates the system under the edition the authority having jurisdiction adopts. Outputs are drafts for review by the licensed professional of record.