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

Understanding and Controlling Water Hammer in a Pumped Water System

By Bob Pelikan
August 1, 2002
Robert Pelikan takes a closer look at the causes of water hammer and considers some remedies.

We've all experienced water hammer at home -- the shower valve is closed abruptly, or the sprinkler system valve closes at the end of the cycle, or the clothes washer fill cycle ends -- and bam! All the pipes in the house rattle. Any time you have a high flow velocity, particularly in a long pipe run, and there is a sudden change in velocity, water hammer can occur.

The resulting pressure wave is transmitted throughout the system, subjecting every component in the system to pressures approaching 10 times the normal system pressure. The pressure returns to normal only when it is dissipated by friction loss, pipe expansion, or when something gives -- a valve or section of pipe. Let's take a closer look at the causes of water hammer and consider some remedies.

For water hammer to occur, several conditions must be present -- sufficient flow velocity, a sufficiently long pipe run, an abrupt change in velocity and a rigid piping system. Regarding flow velocity, it generally is agreed that water flow velocities below 5 feet per second (fps) preclude the possibility of water hammer. As to an abrupt change in velocity, it can be either rapid acceleration (pump start/valve opening) or rapid deceleration (pump stop/valve closure).

This first formula is used to calculate the velocity change timeframe below which water hammer occurs, based on the length of the pipe run. The second formula offers a means for calculating the maximum pressure surge resulting from water hammer in a rigid piping system.

The formula used to calculate the critical time factor that is the minimum time duration for a valve to open or close, or for a pump to start or stop, without causing water hammer, is as follows:

Critical time factor in seconds: Tc = 2L/S

Where: L = length of pipe in feet
S = Speed of sound in water (4,860 fps)

For example, if we have a 400-foot pipe run from the well to the house, the critical time factor would be:

Tc = 2 x 400 / 4,860
Tc = 0.16 seconds.

This means as long as the pump takes less than 0.16 seconds to start, or if a valve in the house is closed in less than 0.16 seconds, your pressure tank better be in good working order. If it is water logged, you may have a water hammer every time the pump starts or a valve is closed.

What then would be the worst case peak pressure caused from water hammer? The Instrument Society of America suggests the following formula for a rigid piping system based on the assumption that the shock wave will travel at the speed of sound, which is 4,860 fps for water. Of course, no piping system is absolutely rigid, so the actual peak pressure would be a little less than these numbers.

Ps = Po + (64V x SG)

Where: Ps = Maximum pressure surge in psig
Po = Normal system operating pressure in psig
V = Velocity of fluid in fps
SG = Specific gravity of fluid (1 for water)

Figure 1. Courtesy of Flomatic Valves.
Let's assume a 30/50 pressure switch, 20 gpm in 1-inch schedule 80 pipe. The velocity of 20 gpm in 1-inch schedule 80 pipe would be about 7.5 fps. Therefore, the maximum pressure surge would be:

Ps = 50 + (64 x 7.5 x 1) = 537.5 psig

Now that we know how to calculate the severity of the water hammer problem, how can we protect our system? Start with a good system design. Size the piping such that the velocity does not exceed 5 fps. In the above example, if 1 1/4-inch pipe had been used instead of 1-inch, the velocity at 20 gpm would have been on the order of 4 fps verses 7.5 fps, and water hammer would not have been an issue. Also, make sure the pressure tank is checked regularly and, at the first sign of air loss, fix the problem or replace the tank. Make sure there is not a check valve between the house and the pressure tank. You want any shock waves generated in the house to expand into the pressure tank, and a check valve would prevent that from happening.

Consider using a flow control valve to reduce the peak flow velocity to below 5 fps. Consider installing a stand pipe or small surge tank near the source of the water hammer. Consider replacing 1?inch turn ball valves with gate valves, which open more slowly, or train the ball valve users to open and close them slowly.

In larger systems, pilot-operated flow and pressure control valves (Figure 1) can control the speed at which the velocity changes, be it on the pump end or in the distribution system. Electronic soft starts and variable speed drives are another good solution to water hammer caused by pumps because they can be programmed to ramp up the pump speed slowly.

Whether it be a small residential water system or large commercial piping system, water hammer can be a major problem. With an understanding of the factors contributing to the problem and access to the necessary tools, it is possible to tame this insidious gremlin and provide your customer with a quiet, long-lasting pumped water system.

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...
    Markets
    By: Jeff Garby
  • Wayne Nash

    Pipe Stuck? Common Causes and Solutions for Drillers

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

    Selecting and Sizing Submersible Pump Cable

    This article helps pump installers and servicers decide...
    Opinions
    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: 21st Century Drillers | Part 1 DEMAND

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

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

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

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

  • Controlling the Amount of Usable Water in Conventional Pressure Tanks

    See More
  • Tech Topics: Plumbing the Pressure Tank in a Submersible Water System

    See More
  • The Fundamentals of Pumped Water Systems

    See More

Related Products

See More Products
  • M:\General Shared\__AEC Store Katie Z\AEC Store\Images\ND\new site\water-and-wastewater-treatm.gif

    Water and Wastewater Treatment: A Guide for the Nonengineering Professional, Second Edition

  • M:\General Shared\__AEC Store Katie Z\AEC Store\Images\ND\new site\water-well-pumps.gif

    Audel Water Well Pumps and Systems Mini-Ref

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