Friction Loss Calculator

Inputs

FLOW RATE (Q):

m³/hr

Kinematic Viscosity (𝜐):

cSt

Pipe Diameter (D):

mm

Pipe Length (L):

m

Pipe Material:

Specific Roughness (ε): —

Results

AVE. VELOCITY (V)

—

m/s

REYNOLDS NUMBER (𝑅𝑒)

—

DARCY FRICTION FACTOR (𝑓)

—

Values update automatically as you change inputs.

3‑K (Darby) — Fittings by Subtype

90° Elbow, Threaded

Standard Radius (R/D = 1)

Long Radius (R/D = 1.5)

90° Elbow, Flanged or Welded

Standard Radius (R/D = 1)

Long Radius (R/D = 2)

Long Radius (R/D = 4)

Long Radius (R/D = 6)

90° Elbow, Mitered

1 weld 90°

2 welds 45°

3 welds 30°

45° Elbow, Threaded

Standard Radius (R/D = 1)

Long Radius (R/D = 1.5)

45° Elbow, Mitered

1 weld 45°

2 welds 22.5°

180° Bend

threaded, close-return (R/D = 1)

flanged (R/D = 1)

all types (R/D = 1.5)

Tee Through-branch as an Elbow

threaded (r/D = 1)

threaded (r/D = 1.5)

flanged (r/D = 1)

stub-in branch

Tee Run-through

threaded (r/D = 1)

flanged (r/D = 1)

stub-in branch

Valves & Misc.

Angle valve, 45°, β=1

Angle valve, 90°, β=1

Globe valve, standard β=1

Plug valve, branch flow

Plug valve, straight through

Plug valve, three-way (flow through)

Gate valve, standard β=1

Ball valve, standard β=1

Diaphragm, dam type

Swing check valve

Lift check valve

Reducer / Expander

Angle (θ)

D (mm)

d (mm)

Reduction

Angle <45°

RE<2500

RE>2500

Angle >45°

RE<2500

RE>2500

Expansion

Angle <45°

RE<4000

RE>4000

Angle >45°

RE<4000

RE>4000

3‑K Results

REDUCER / EXPANDER LOSS

—

m

Total head loss fittings

0.0000

m

3k darby total friction loss (m)

0.0000

m

3‑K uses K(Re,D) = K1/Re + K∞·(1 + Kd/D^0.3) with D in mm.

Friction Loss Calculator

Inputs

Results

Above 2500 Reynolds — Fittings / Minor Losses

Results

3‑K (Darby) — Fittings by Subtype

90° Elbow, Threaded

90° Elbow, Flanged or Welded

90° Elbow, Mitered

45° Elbow, Threaded

45° Elbow, Mitered

180° Bend

Tee Through-branch as an Elbow

Tee Run-through

Valves & Misc.

Reducer / Expander

Reduction

Angle <45°

Angle >45°

Expansion

Angle <45°

Angle >45°

3‑K Results