🔧

Pipe Flow & Pressure Drop Simulator

Darcy-Weisbach friction loss, Reynolds number, Moody friction factor, and minor losses via K-factor method. Real-time comparison across all standard pipe sizes.

System Inputs

Pipe Material

Pipe Size (selected for diagram)

Flow Rate20 GPM

Pipe Run Length100 ft

Fittings (K-Factor)

90° Standard Elbow (K=0.9)

45° Elbow (K=0.4)

Tee (through) (K=0.6)

Tee (branch) (K=1.8)

Gate Valve (open) (K=0.2)

Ball Valve (open) (K=0.05)

Globe Valve (open) (K=10)

Check Valve (swing) (K=2.5)

Reducer (gradual) (K=0.5)

Sharp Entrance (K=0.5)

Selected Size: 1¼"

Velocity4.29 fps

Reynolds Number40.5k

Flow RegimeTurbulent

Friction Factor f0.0219

Friction Loss2.365 psi (2.365 psi/100ft)

Minor Losses0.434 psi (ΣK=3.5)

Total ΔP2.798 psi

Roughness ε0.000059" (ε/D=4.28e-5)

Pressure Drop Comparison — All Standard Sizes at 20 GPM, 100 ft

Size	ID (in)	Velocity (fps)	Re	Regime	f	Friction ΔP (psi)	Minor ΔP (psi)	Total ΔP (psi)	Velocity Check
½"	0.622	21.12	89.9k	Turbulent	0.0188	108.917	10.513	119.430	Too fast
¾"	0.824	12.03	67.9k	Turbulent	0.0197	28.045	3.413	31.459	Too fast
1"	1.049	7.42	53.3k	Turbulent	0.0207	8.793	1.300	10.092	Acceptable
1¼"	1.38	4.29	40.5k	Turbulent	0.0219	2.365	0.434	2.798	Acceptable
1½"	1.61	3.15	34.7k	Turbulent	0.0227	1.132	0.234	1.366	Good
2"	2.067	1.91	27.1k	Turbulent	0.0240	0.344	0.086	0.430	Acceptable
2½"	2.469	1.34	22.7k	Turbulent	0.0251	0.148	0.042	0.190	Acceptable
3"	3.068	0.87	18.2k	Turbulent	0.0265	0.053	0.018	0.070	Acceptable
4"	4.026	0.50	13.9k	Turbulent	0.0284	0.014	0.006	0.020	Acceptable
6"	6.065	0.22	9.2k	Turbulent	0.0317	0.002	0.001	0.003	Too slow

Design targets: Domestic water supply 2–4 fps, chilled/hot water 2–4 fps, fire protection 4–10 fps. Maximum recommended pressure drop 4–5 psi/100 ft for domestic water supply. Velocity below 0.5 fps risks sediment buildup; above 8 fps risks erosion in copper and noise in all piping.