Find the best tutors and institutes for Engineering Diploma Tuition

Find Best Engineering Diploma Tuition

Please select a Category.

Please select a Locality.

No matching category found.

No matching Locality found.

Outside India?

Search for topics

Calculating Frictional Pressure Drop in Pipelines

Goutam Das
26/10/2020 0 0


Very frequently, we need to calculate frictional pressure drops in pipelines. Many of us may have domestic pumps in our households. After we estimate the pump flow from expected consumption of water, we need to calculate the pump head for purchasing a suitable pump. The following is an example of calculation of pressure drop when the flow and pipe geomerty is known.

Input Data(assumed)

1. Pipe flow -10 m3/h

2. Fluid-Water at 250C. 

3. Pipe material-commercial galvanised carbon steel (absolute roughness ε=0.15 mm)

4.. Flow geometry as below(total pipe length L=20 m).





Step-1 Calculation of flow velocity

From pipe dimension table for 25mm NB std thickness pipe

OD (D)=33.4 mm

Thickness (t)=3.38 mm

Hence ID(d)=D-2t=33.4-2x3.38=26.64 mm=0.02664 m

Pipe flow area (A)=(π/4)d2= (π/4)x0.026642=0.000557 m2 

Pipe flow (Q)=10 m3/h=10/3600=0.00278 m3/s

Hence pipe flow velocity(V)=Q/A=0.00278/0.000557=4.98 m/s

Step-2 Calculation of Darcy's Friction Factor(f)

Kinematic viscosity of water(ν)=8.92x10-7 m2/s

Reynold's number (Re)=Vd/ν=4.98x0.02664/8.92x10-7=1.9x105

Re>2000 hence flow is turbulent

For determining f we use Moody's chart s below:

 Relative roughness (ε/d)=0.15/1000/0.02664=0.005631

We noe find f from Re and ε/d as follows

Hence f=0.031

 Step 3 Calculation Pipe Friction Drop

 Total pipe length L=20 m

Minor losses

Minor losses are calculated by K factors. Different K factors are available in the internet(refer Crane Technical Paper 410)

a) Inlet loss-K1=1

b) Foot valve with strainer-pressure drop Δpf1=0.1 bar(assumed)=1x104 Pa

c) Elbows 900 -3 Nos, K2=3x30f=3x30x0.031=2.79

d) Gate valve -2 nos, K3=2x8f=2x8x0.031=0.496

e) Exit loss, K4=1

Total head drop

hf= (fL/D+K1+K2+K3+K4)V2/2g+ Δpf1/ρg (Note :ρ=density=1000 kg/m3)


=37.12 mwc

Step 4 Calculation of Pump Head

In addition to frictional head loss we have static head increase

Pump head (H)=(h1+h2)+hf= 3+12+37.12

H=52.12 mwc

We normally take some margin (say 15 %)for future increase in pipe friction drop due to ageing and calculation uncertainties.


H=52.12x1,15=60 mwc

Pump details, 10 m3/h flow, 60 mwc head.

0 Dislike
Follow 2

Please Enter a comment


Looking for Engineering Diploma Tuition ?

Find best Engineering Diploma Tuition in your locality on UrbanPro.

Are you a Tutor or Training Institute?

Join UrbanPro Today to find students near you

Looking for Engineering Diploma Tuition Classes?

Find best tutors for Engineering Diploma Tuition Classes by posting a requirement.

  • Post a learning requirement
  • Get customized responses
  • Compare and select the best

Looking for Engineering Diploma Tuition Classes?

Find best Engineering Diploma Tuition Classes in your locality on UrbanPro

Post your learning requirement

UrbanPro.com is India's largest network of most trusted tutors and institutes. Over 55 lakh students rely on UrbanPro.com, to fulfill their learning requirements across 1,000+ categories. Using UrbanPro.com, parents, and students can compare multiple Tutors and Institutes and choose the one that best suits their requirements. More than 7.5 lakh verified Tutors and Institutes are helping millions of students every day and growing their tutoring business on UrbanPro.com. Whether you are looking for a tutor to learn mathematics, a German language trainer to brush up your German language skills or an institute to upgrade your IT skills, we have got the best selection of Tutors and Training Institutes for you. Read more