h_f = 10.67 × (Q^1.852) / (C^1.852 × D^4.87) × L_eq
| Fitting | Equivalent length (m) per 100 mm pipe dia | |---------|-------------------------------------------| | 90° elbow | 0.3 – 0.6 | | Tee (straight) | 0.6 – 1.2 | | Tee (branch) | 1.5 – 2.4 | | Gate valve (open) | 0.15 – 0.3 | | Globe valve (open) | 6 – 10 | | Swing check valve | 2 – 4 | | Strainer | 3 – 6 | Darcy-Weisbach (more accurate): chilled water pump head calculation excel sheet
h_f = f × (L_eq / D) × (v² / (2g))
L_eq = L_pipe + Σ (N_fitting × L_fitting_eq) h_f = 10
1. Objective To provide a structured, reusable Excel-based method for calculating the total dynamic head (TDH) of a chilled water pump in a closed-loop HVAC system. Accurate head calculation ensures proper pump selection, energy efficiency, and system reliability. 2. Key Parameters for Pump Head Calculation In a closed chilled water system, the total head (in meters or feet) is the sum of: schedule 40 steel pipe):
Common equivalent lengths (for water, schedule 40 steel pipe):