Inputs
If inflow is 0, calculator estimates inflow from rainfall:
Q≈0.0104·C·i·A (GPM) or metric equivalent.
in
Recommendation
Recommended sizing target
— GPM @ — ft
≈ — HP (η=0.50)
Operating point
— GPM, — ft
Ready
Basin cycling
Drawdown volume: — gal
Run time: — s • Fill time: — s
Cycles/hour: — (target ≤ 10)
Power & cost
Pump watts: — W • Duty: —
Use: — kWh/mo • Cost: $—/mo
Backup runtime: — h
Pump vs System Curve
TDH(Q) includes static, friction, and minor losses
Head breakdown at operating point
Basin timeline (2 cycles)
Velocity @ op: — ft/s
Friction @ op: — ft
Minor @ op: — ft
Static: — ft
Advice: Enter your inputs to size the pump and pipe. Keep velocity 3–8 ft/s to balance friction vs. noise and water hammer.
Notes & Assumptions
- Imperial mode uses Hazen–Williams for friction:
h_f(ft)=4.52·(L/100)·Q^1.85/(C^1.85·d^4.87), Q in GPM, d in inches. - Metric mode uses Darcy–Weisbach with Swamee–Jain for friction factor; head in meters then converted where needed.
- Minor losses:
h_m=K·v²/(2g)with g=32.174 ft/s² (imperial). K defaults: 90°=0.9, 45°=0.4, tee-thru=0.6, union=0.2, swing CV≈2.5, spring CV≈1.0, outlet 1–2. - Horsepower:
HP=Q_gpm·TDH_ft·SG/(3960·η). Energy viaP=ρgQH/η. - Generic pump curves are illustrative; import real curves for exact sizing.