About This Calculator

This tool calculates the sizing requirements for a centrifugal pump. It determines the Total Dynamic Head (TDH), Net Positive Suction Head Available (NPSHa), friction losses, and power needs based on your inputs for fluid, suction, discharge, and pump details. It also plots TDH, NPSHa, and power against flow rate to help you visualize performance.

Formulas Used

• Friction Loss (Pipe): h_f = f × (L/D) × (v²/(2g))
  Calculates head loss in pipes. f is friction factor, L is length, D is diameter, v is velocity, g is gravity.
• Friction Loss (Fittings): h_f = K × (v²/(2g))
  Head loss from fittings like elbows. K is the fitting coefficient.
• Total Friction Loss: h_f,total = h_f,pipe + h_f,fittings
  Adds pipe and fitting losses for suction or discharge.
• Velocity: v = Q / A
  Flow rate Q divided by pipe area A = π × (D/2)².
• Total Dynamic Head (TDH): TDH = (h_d,static - h_s,static) + h_f,discharge + h_pressure
  Total head the pump must overcome, including static difference, discharge friction, and pressure.
• NPSH Available (NPSHa): NPSHa = h_atm + h_s,static - h_f,suction - h_vapor
  Head available to avoid cavitation, from atmospheric pressure, suction head, minus friction and vapor pressure.
• Hydraulic Power: P_h = (ρ × g × Q × TDH) / 1000
  Power to move fluid in kW. ρ is density, Q is flow rate.
• Brake Power (BP): BP = P_h / η
  Actual power needed, adjusted for pump efficiency η.

Step-by-Step Process

1. Collect inputs: fluid, suction, discharge, and pump details.
2. Convert units to feet, inches, GPM (friction) or SI (power).
3. Calculate velocities for suction and discharge pipes.
4. Compute friction losses for suction and discharge (pipe + fittings).
5. Find TDH: static head difference + discharge friction + pressure.
6. Find NPSHa: atmospheric head + suction head - suction friction - vapor head.
7. Calculate hydraulic power, then brake power with efficiency.
8. Plot TDH, NPSHa, and power over a range of flow rates.