Line sizing with example.pdf

8/17/2019 Line sizing with example.pdf

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• Darcy -Weisbach equation use to calculate pressure drop/head loss

through pipe.• Head Loss= f (L/D)( V2/2g)• Head Loss= p1-p2/ ρg• Δp= f (L/D)( ρV2/2)

•

Where f =Friction factor L= length of pipeD= dia. Of pipeV= Velocity of liquid ρ= density of liquid


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Friction Factor and Reynolds no•

Friction factor ( f ) is decided by flow of fluid.• Reynolds no decide type of flow.

1. Re


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Churchill Equation

ε: Pipe Roughness


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Moody chart


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Pipe roughness

Material Roughness (mm)Drawn Tubing, Glass, Plastic 0.0015-0.01

Drawn Brass, Copper, Stainless Steel (New) >0.0015-0.01

Flexible Rubber Tubing - Smooth 0.006-0.07

Flexible Rubber Tubing - Wire Reinforced 0.3-4

Stainless Steel 0.03Wrought Iron (New) 0.045Carbon Steel (New) 0.02-0.05

Carbon Steel (Slightly Corroded) 0.05-0.15

Carbon Steel (Moderately Corroded) 0.15-1Carbon Steel (Badly Corroded) 1-3Carbon Steel (Cement-lined) 1.5

Asphalted Cast Iron 0.1-1Cast Iron (new) 0.25

Cast Iron (old, sandblasted) 1

Sheet Metal Ducts (with smooth joints) 0.02-0.1

Galvanized Iron 0.025-0.15

Wood Stave 0.18-0.91Wood Stave, used 0.25-1Smooth Cement 0.5

Concrete – Very Smooth 0.025-0.2

Concrete – Fine (Floated, Brushed) 0.2-0.8

Concrete – Rough, Form Marks 0.8-3Riveted Steel 0.91-9.1

Water Mains with Tuberculations 1.2Brickwork, Mature Foul Sewers 3


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Methods to Calculate head loss/pressure loss fromfittings

• 3K method• 2K method• Equivalent length method


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3K Method

Chemsys Process Engineering P. LtdFitting Types K 1 K∞ Kd (in0.3) Kd (mm 0.3)

90° Elbow, ThreadedStandard Radius (R/D =

1)800 0.14 4 10.6

Long Radius (R/D = 1.5) 800 0.071 4.2 11.1

90° Elbow, Flanged orWelded

Standard Radius (R/D =1)

800 0.091 4 10.6

Long Radius (R/D = 2) 800 0.056 3.9 10.3

Long Radius (R/D = 4) 800 0.066 3.9 10.3

Long Radius (R/D = 6) 800 0.075 4.2 11.1

90° Elbow, Mitered1 weld 90° 1000 0.27 4 10.62 welds 45° 800 0.068 4.1 10.83 welds 30° 800 0.035 4.2 11.1

45° Elbow, ThreadedStandard Radius (R/D =

1)500 0.071 4.2 11.1

Long Radius (R/D = 1.5) 500 0.052 4 10.6

45° Elbow, Mitered1 weld 45° 500 0.086 4 10.6

2 welds 22.5° 500 0.052 4 10.6

180° Bend

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

1000 0.23 4 10.6

flanged (R/D = 1) 1000 0.12 4 10.6

all types (R/D = 1.5) 1000 0.1 4 10.6

Tee Through-branch asan Elbow

threaded (r/D = 1) 500 0.274 4 10.6

threaded (r/D = 1.5) 800 0.14 4 10.6

flanged (r/D = 1) 800 0.28 4 10.6stub-in branch 1000 0.34 4 10.6

Tee Run-throughthreaded (r/D = 1) 200 0.091 4 10.6flanged (r/D = 1) 150 0.05 4 10.6stub-in branch 100 0 0 0

Angle valve45°, full line size, β = 1 950 0.25 4 10.6

90° full line size, β = 1 1000 0.69 4 10.6

Globe valve standard, β = 1 1500 1.7 3.6 9.5

Plug valve

branch flow 500 0.41 4 10.6straight through 300 0.084 3.9 10.3three-way (flow

through)300 0.14 4 10.6

Gate valve standard, β = 1 300 0.037 3.9 10.3Ball valve standard, β = 1 300 0.017 3.5 9.2

Diaphragm dam type 1000 0.69 4.9 12.9

Swing check valveVmin = 35[ ρ

(lbm/ft3)]−1/21500 0.46 4 10.6

Lift check valveVmin = 40[ ρ

(lbm/ft3)]−1/22000 2.85 3.8 10

Head Loss= K( V2/2g)


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Equivalent length MethodFitting Types (L/D)eq

90° Elbow Curved, ThreadedStandard Radius (R/D = 1) 30

Long Radius (R/D = 1.5) 16

90° Elbow Curved, Flanged/Welded

Standard Radius (R/D = 1) 20

Long Radius (R/D = 2) 17



90° Elbow Mitered1 weld (90°) 602 welds (45°) 153 welds (30°) 8

45° Elbow Curved. ThreadedStandard Radius (R/D = 1) 16

Long Radius (R/D = 1.5)

45° Elbow Mitered1 weld 45° 15

2 welds 22.5° 6

180° Bendthreaded, close-return (R/D = 1) 50

flanged (R/D = 1)all types (R/D = 1.5)

Tee Through-branch as an Elbow

threaded (r/D = 1) 60threaded (r/D = 1.5)

flanged (r/D = 1) 20stub-in branch

Tee Run-throughthreaded (r/D = 1) 20flanged (r/D = 1)stub-in branch

Angle valve45°, full line size, β = 1 55

90° full line size, β = 1 150

Globe valve standard, β = 1 340

Plug valve

branch flow 90straight through 18

three-way (flow through) 30

Gate valve standard, β = 1 8Ball valve standard, β = 1 3

Diaphragm dam type

Swing check valve Vmin = 35[ ρ (lbm/ft3)]−1/2 100

Lift check valve Vmin = 40[ ρ (lbm/ft3)]−1/2 600Hose Coupling Simple, Full Bore 5

1. Calculate Equivalent lengthwith reference to given chart.

2. Add this length to straightlength and calculate headloss/pressure drop.


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Z1 Z110

L

Z2

L*Sin10

• Example 1. Oil, with ρ= 900 kg/ m3 and kinematic coefficient of viscosity γ=0.00001 m2/ s, flows at Q = 0.2 m3/ s through 500 m of 200 -mm diametercast-iron pipe. Determine (a) the head loss and (b) the pressure drop if the

pipe slopes down at 10 in the flow direction.


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• Example 2. Calculation of Pressure Loss: if fittings are present.(3K)•

Pipe Size: DN100 (4")• Pipe Diameter (Nominal): 4"• Pipe Internal Diameter:102.3 mm• Pipe Length: 50 m Fittings: 3 x 90° long radius (R/D = 2)• flanged elbows Fluid Velocity: 3 m/s• Fluid Density: 1000 kg/m 3• Reynolds Number:306,900• Friction Factor: 0.018• Gravitational Acceleration:9.81 m/s

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Line sizing with example.pdf

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