NFPA 13 occupancy hazard classification. Determines design density and remote area. Light: offices/churches. Ordinary 1: parking garages. Ordinary 2: machine shops. Extra 1/2: flammable liquid handling.

Coverage area per individual sprinkler head in square feet. NFPA 13 maximums: 200 ft2 for light hazard, 130 ft2 for ordinary hazard. Determines flow per head from design density. Typical: 120-225 ft² per sprinkler for standard coverage.

Number of sprinkler heads within the hydraulically most remote design area. Calculated as design area / coverage area per head. Typical: 8-20 heads depending on hazard class.

Sprinkler K-factor in gpm/psi^0.5. Relates flow to pressure: Q = K*sqrt(P). Standard pendant/upright: K=5.6. Large-drop: K=11.2. ESFR: K=14.0-25.2. Per NFPA 13 Table 7.2.2.1. If omitted, defaults to 5.6 (standard pendant/upright).

Center-to-center spacing between sprinkler heads along branch lines in feet. NFPA 13 max: 15 ft for light hazard, 12-15 ft for ordinary. Used to estimate branch pipe length for friction loss.

Pipe wall schedule designation. Common: '40' (standard), '10' (thin-wall stainless). Determines inside diameter for hydraulic calculations. Schedule 40 is standard for wet systems. If omitted, defaults to '40'.

Pipe material for Hazen-Williams C-factor. Supported: carbon_steel (C=120), stainless_steel (C=140), galvanized_steel (C=120), copper (C=140), cpvc (C=150), cast_iron (C=100). If omitted, defaults to carbon_steel (C=120).

Available static water supply pressure at the base of the sprinkler riser in psi. Compared against total system demand (remote head pressure + friction losses) to determine supply adequacy. Typical: 40-100 psi from city water, check hydrant flow test data.