Water Hammer 101: Understanding the Threat to Processes & Facilities

What is water hammer?

Water hammer, also known as hydraulic shock or valve slam, is a pressure surge or wave caused when a fluid in motion is forced to stop or change direction suddenly. This phenomenon commonly occurs in piping systems where the flow of a fluid is abruptly halted or redirected due to valve closure, pump start or stop, or sudden changes in flow velocity. When this happens, the kinetic energy of the moving fluid is converted into pressure energy, creating a shockwave that travels through the piping system.

Why is water hammer harmful?

Water hammer can be harmful to industrial processes and facilities for several reasons:

  • Equipment damage: The sudden increase in pressure caused by water hammer can exert significant stress on pipes, valves and other components of the system, leading to damage or even failure. This can result in costly repairs and downtime.
  • Noise and vibration: Water hammer often produces loud banging noises and vibrations, which can be disruptive and potentially damaging to nearby equipment and structures.
  • Reduced efficiency: The pressure surges caused by water hammer can disrupt the normal operation of equipment, leading to reduced efficiency and performance. This can affect processes that rely on precise control of fluid flow, such as water treatment plants or manufacturing facilities.
  • Safety risks: In extreme cases, water hammer can pose safety risks to personnel and equipment. For example, sudden pressure surges can cause pipes to burst, releasing large amounts of pressurized fluid, leading to injuries or environmental damage.

To mitigate the effects of water hammer, engineers employ various techniques such as installing surge suppressors (also known as water hammer arrestors), using gradual valve closures, and designing piping systems with adequate flexibility and cushioning to absorb pressure fluctuations. Proper design, operation and maintenance of piping systems are essential to minimize the risks associated with water hammer.

Case Study – Eliminating Water Hammer at The Jimmy Smith Wastewater Treatment Plant (WTP) in Boone, North Carolina

Wastewater Treatment Plant - Boone, North CarolinaThe Jimmy Smith Wastewater Treatment Plant (WTP) is located in Boone, North Carolina, and sits at an elevation of about 3,300 feet with a permitted capacity of 4.82 million gallons per day. Since it opened in the 1990s, however, the plant has experienced multiple water hammer issues.

The three influent pumps at the plant feed into a common header that goes uphill for 80 feet before discharging into an aeration basin. The plant uses traditional 16-inch American Water Works Association (AWWA) swing check valves, which have experienced sometimes violent pressure resulting in water hammer and equipment damage. The facility’s elevation and pump dead head pressure create a perfect storm.

In February 2013, the Jimmy Smith WTP had just undergone the rebuilding of all three of its influent pumps when the latest in a string of violent water hammer events occurred, destroying one of the check valves. The valve disc had slammed so violently that it wrenched the seat ring from the valve body, warping the bronze seat ring into an egg shape.

Proco presented a 16-inch Proco ProFlex™ Style 750 that met system requirements and included flush ports. Since the check valve is mounted to a rubber expansion joint on the discharge side of the check valve, Proco also included a structural support for the existing expansion joint.

The new valve was installed on May 13, 2013, and the pump’s water hammer issues have since been eliminated, despite initial skepticism from plant operators regarding the valve’s design. As for future possible problems with other pumps, operators at WTP say Proco is their first choice.

How can Proco help?

When searching for components that will help to prevent and avoid water hammer in facilities and other applications, check valves can be especially helpful in reducing the risk of the reverse flow that can cause water hammer.

Proco Product’s duckbill check valves, such as the Proco ProFlex™ Style 750, are a great option. They are barnacle and algae-resistant for projects that may be in salt water and have an all-rubber construction to resist abrasive slurries. Their unique design prevents backflow and lends itself to minimal maintenance and energy costs.

When choosing a check valve, many considerations can come into play and are important to assess when choosing the right component, including application, flow rate, inlet pressure, back pressure, and location. Regardless of your situation, the folks at Proco are always happy to help. If you need help deciding which component is the right one for your application, reach out



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