The Driller
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • CLASSIFIEDS
  • EQUIPMENT
  • SAFETY
  • VIDEOS
  • EDUCATION
  • SOURCEBOOK
  • EVENTS
  • SUBMIT
  • ABOUT
  • SIGN UP
cart
facebook twitter linkedin youtube
  • NEWS
  • Water
  • Geothermal
  • Construction
  • Environmental
  • Mining
  • All Industry News
  • EQUIPMENT
  • Rigs & Heavy Equipment
  • Consumables
  • Pumps
  • Featured Products
  • VIDEOS
  • Newscast
  • Drill Talks
  • Ask Brock
  • Emerging Drillers
  • EDUCATION
  • Drilling Business Insights
  • Reference Desk
  • Sponsored Insights
  • EVENTS
  • Conferences & Demo Days
  • Newscast LIVE
  • SUBMIT
  • Drillers @Work
  • ABOUT
  • Contact
  • Advertise
The Driller
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
The Driller
  • NEWS
    • Water
    • Geothermal
    • Construction
    • Environmental
    • Mining
    • All Industry News
  • CLASSIFIEDS
  • EQUIPMENT
    • Rigs & Heavy Equipment
    • Consumables
    • Pumps
    • Featured Products
  • SAFETY
  • VIDEOS
    • Newscast
    • Drill Talks
    • Ask Brock
    • Emerging Drillers
  • EDUCATION
    • Drilling Business Insights
    • Reference Desk
    • Sponsored Insights
  • SOURCEBOOK
  • EVENTS
    • Conferences & Demo Days
    • Newscast LIVE
  • SUBMIT
    • Drillers @Work
  • ABOUT
    • Contact
    • Advertise
  • SIGN UP

Pressure Loss Due to Friction – Part 1

By Bob Pelikan
September 2, 2003
In "Tech Topics," Bob Pelikan examines the effects of friction on a pumped water system.

Last month, we examined two of the three factors to be considered when determining the pressure requirements of a pump — household working pressure and lift pressure. The third factor is pressure drop due to friction loss. Friction loss is the energy lost due to friction when two objects move in relationship to one another. When you drive your truck down the road at 30 mph, the pressure caused by the friction of the air against your truck uses up a certain amount of horsepower. As your speed increases, more horsepower is required to overcome the friction of the air. This is friction loss, and it works against you in a piping system, just as it does on the highway.

The faster water in a pumped system flows, the higher the pressure loss.
As water travels through the pipes of a water system, friction causes the pressure to drop so that the pressure at the outlet is always lower than the pressure at the inlet (if the pipe system is level). This is called the friction loss or pressure drop, and it varies depending on several factors:

  • The viscosity of the fluid. Viscosity is the measure of a fluid’s resistance to flow. The higher the viscosity, the more pressure it takes to push it through a pipe. Molasses is harder to pump than water, but since we only are considering water systems in this article, all the tables and factors presented here are calculated for the viscosity of water.

  • The smoothness of the inside of the pipe. A pipe that is coated with calcium deposits and rust will cause more pressure drop than a clean, smooth pipe. The accompanying tables are for new, smooth pipe, so if your water has high calcium content, which will cause the pipes in your system to be coated with deposits, increase the pressure drop in your calculations by 20 percent.

  • The inside diameter of the pipe. For a given flow rate, the smaller the pipe, the greater the pressure loss.

  • The flow rate or velocity of the fluid. The faster it flows, the higher the pressure loss.

  • The number of valves and fittings in the system. When a fluid has to change direction or flow through an irregular object, more pressure is lost than when it flows through a straight section of pipe. The amount of flow restriction for valves and fittings is expressed in terms of equivalent lengths of pipe.


Table 1. Equivalent lengths of fittings.
Fortunately for us, engineers have created a set of tables for determining the pressure loss of water in different types of valves and fittings. For instance, a 1-inch diameter copper elbow causes the same amount of pressure drop as 3 feet of 1-inch copper pipe. Table 1 shows equivalent lengths of some common fittings used in pumping systems. Fittings made from different materials have varying pressure drops, so be sure to use the table for the type of fittings in your system, i.e., copper, PVC, steel, etc. The Uniform Plumbing Code has tables of pressure drop in fittings for various materials, as do engineering manuals from most pump manufacturers.

Table 2. Velocity in feet per second and pressure drop in feet of head and PSI per 100 feet of copper pipe.

Pressure Loss in Pipes

We commonly speak of friction pressure loss in terms of pressure drop per 100 feet of pipe. Tables depicting pressure drop are called dynamic pressure drop tables because they show the pressure loss due to the moving (dynamic) water through the pipes. The other kind of pressure loss, which we talked about last month, is called static pressure loss, which is the loss due to differing elevations in the system. Table 2 shows pressure loss in terms of feet of head and pounds per square inch, as well as velocity in terms of feet per second for copper pipe. It is important to size your piping system with velocity in mind. The National Hydraulic Institute recommends 7 feet/second as a maximum design velocity for optimum hydraulic efficiency and minimal erosion. As you can see in Table 2, velocity decreases dramatically as pipe size goes up for a given flow rate. Contact your pump or pipe supplier for similar tables for PVC and steel pipe.

Next month, we will use this information to calculate the pressure drop in the piping system in a typical residential water system. ’Til then ….

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Bob is a regular contributor to The Driller. Contact bobpelikan@comcast.net to request a copy of The Pump Book, a compilation of Bob's columns for reference or training available for only $20.

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • geotechnical drilling rig

    6 Onsite Phrases Environmental Drillers Hate

    Here are six phrases that highlight common frustrations...
    Environmental Monitoring
    By: Jeff Garby
  • Wayne Nash

    Pipe Stuck? Common Causes and Solutions for Drillers

    If you have drilled for any length of time, sooner or...
    World According to Wayne
    By: Wayne Nash
  • submersible pumps, water well pumps

    Selecting and Sizing Submersible Pump Cable

    This article helps pump installers and servicers decide...
    Pumps
    By: Bob Pelikan
You must login or register in order to post a comment.

Report Abusive Comment

Subscribe For Free!
  • eNewsletters
  • Online Registration
  • Subscription Customer Service
  • Manage My Preferences

The Driller Newscast: New York Geo Talks 2025 Conference with Hands-on Driller Education

The Driller Newscast: New York Geo Talks 2025 Conference with Hands-on Driller Education

The Driller Newscast: Coiled Tubing Drilling and the Future of Geothermal

The Driller Newscast: Coiled Tubing Drilling and the Future of Geothermal

The Driller Newscast, Episode 147: Global Geothermal Collaboration at NY-GEO 2025

The Driller Newscast, Episode 147: Global Geothermal Collaboration at NY-GEO 2025

The Driller Newscast: 21st Century Drillers | Part 1 DEMAND

The Driller Newscast: 21st Century Drillers | Part 1 DEMAND

More Videos

Sponsored Content

Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the The Driller audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of The Driller or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

close
  • demo of a DM450 drilling rig during a customer factory visit
    Sponsored byGeoprobe

    Built for You: Smarter Drill Rigs, Stronger Support, Bigger Opportunities

Popular Stories

MainPhotoTwoBrothers.jpg

Two Brothers' Journey Through the Drilling Industry

Tariffs

Tariffs Shake Up the Drilling Industry

AI and Drought Concerns

AI’s Growing Thirst for Water and Power

The Driller Classifieds

COMPRESSORS

EAST WEST MACHINERY & DRILLING IS BUYING AND SELLING AIR COMPRESSORS, AIR BOOSTERS, AIR ENDS & PARTS
Company: East West Machinery

DRILL RIGS

LOOKING FOR LATE MODEL TOPHEADS & DRILLTECH D25'S
Company: Spikes’s Rig Sales

DRILL RIG PARTS

MEETING DRILLERS NEEDS AROUND THE WORLD
Company: East West Machinery

ELEVATORS

SEMCO INC. PIPE ELEVATORS
Company: Semco Inc.

GROUTERS

GROUTING EQUIPMENT - GROUT PUMPS & GROUT HOSE REELS
Company: Geo-Loop Inc.

PUMP HOISTS

SEMCO INC. - BASIC PUMP HOISTS
Company: Semco Inc.

WELL PACKERS

LANSAS PRODUCTS - INFLATABLE WELL PACKERS
Company: Vanderlans Lansas Products

WELL SCREENS

WELL SCREENS & SLOTTED PIPE
Company: Alloy Screen Works

Products

Water Quality Engineering: Physical / Chemical Treatment Processes

Water Quality Engineering: Physical / Chemical Treatment Processes

By carefully explaining both the underlying theory and the underlying mathematics, this text enables readers to fully grasp the fundamentals of physical and chemical treatment processes for water and wastewater.

See More Products

Subscribe to The Driller Newscast

Related Articles

  • Tech Topics: Pressure Loss Due to Friction - Part 1

    See More
  • Tech Topics: Pressure Loss Due to Friction - Part 1

    See More
  • Water Wells

    Calculating Pressure Drop Due to Friction in a Piping System - Part 1

    See More

Related Products

See More Products
  • managed.jpg

    Managed Pressure Drilling 1st Edition

See More Products
×

Dig deeper into the drilling and water supply industry!

Build your knowledge with The Driller, covering the people, equipment and technologies across drilling markets.

SIGN UP NOW
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
    • Classifieds
  • SIGN UP TODAY
    • Create Account
    • eNewsletters
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

The Driller
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
The Driller
  • NEWS
    • Water
    • Geothermal
    • Construction
    • Environmental
    • Mining
    • All Industry News
  • CLASSIFIEDS
  • EQUIPMENT
    • Rigs & Heavy Equipment
    • Consumables
    • Pumps
    • Featured Products
  • SAFETY
  • VIDEOS
    • Newscast
    • Drill Talks
    • Ask Brock
    • Emerging Drillers
  • EDUCATION
    • Drilling Business Insights
    • Reference Desk
    • Sponsored Insights
  • SOURCEBOOK
  • EVENTS
    • Conferences & Demo Days
    • Newscast LIVE
  • SUBMIT
    • Drillers @Work
  • ABOUT
    • Contact
    • Advertise
  • SIGN UP