Required flow rate at the design operating point. Typical: 5-50 GPM for residential, 50-500 GPM for commercial HVAC, 500-5000 GPM for industrial process or municipal systems.

Total static head (elevation difference) the pump must overcome, in feet. Positive when pumping upward. Zero for closed-loop systems (e.g. chilled water). Typical: 0-200 ft for building systems. If omitted, defaults to 0 ft (closed-loop).

Fluid name matching the fluid-properties reference table (e.g. 'water', 'ethylene_glycol_50'). Used to look up density and viscosity at the specified temperature for Reynolds number and head loss calculations. If omitted, defaults to water.

Fluid temperature for property lookup. Affects viscosity and density, which impact friction losses and pump performance. Typical: 4-90 C for water systems. If omitted, defaults to 20 C.

Nominal Pipe Size for the system piping used in head loss calculations. Common sizes: '2', '3', '4', '6', '8', '10', '12'. Must match NPS values in the pipe-sizes reference table. If omitted, defaults to NPS 4.

ASME pipe schedule for ID lookup. Schedule 40 is standard for most applications. Higher schedules (80, 160) have thicker walls and smaller ID. If omitted, defaults to Schedule 40.

Total equivalent straight pipe length in feet for friction loss calculation. Does not include minor losses from fittings (those are added separately via the fittings parameter). Total equivalent pipe length including fittings. Typical: 50-500 ft for building systems. If omitted, defaults to 100 ft.

Pipe material for roughness estimation. Options: 'carbon_steel', 'stainless_steel', 'cast_iron', 'ductile_iron', 'copper', 'PVC', 'HDPE'. Affects Darcy-Weisbach friction factor. If omitted, defaults to carbon_steel.

List of fitting types for minor loss K-factor lookup. Examples: 'elbow_90_std', 'tee_branch', 'gate_valve', 'check_valve_swing'. Each fitting's K factor is summed for total minor losses. If omitted, no minor losses are included.

Specific pump family to evaluate from the pump-curves table (e.g. 'end_suction_3x4x10_full', 'inline_circ_1in_full'). If omitted, all available pump families are evaluated and the best match is recommended based on efficiency and BEP proximity.

Multiplier applied to calculated BHP to determine required motor HP. Industry standard is 1.10-1.15 for pumps up to 100 HP, 1.10 for larger pumps. Accounts for wear, field conditions, and motor service factor. If omitted, defaults to 1.15.