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Can a Pressure Regulator Cause Water Hammer?


Water hammer, also known as hydraulic shock, is a common and often startling phenomenon in plumbing systems. It occurs when a fluid in motion is suddenly forced to stop or change direction, creating a pressure surge or wave that travels through the pipes. This can result in loud banging noises, pipe vibrations, and in severe cases, damage to the plumbing system. Pressure regulators, which are designed to control the pressure of water entering a system, can sometimes contribute to or exacerbate water hammer. In this article, we will explore how pressure regulators can cause water hammer, the underlying mechanisms, and strategies to mitigate this issue.

Understanding Water Hammer

Water hammer occurs when a valve or tap is closed suddenly, causing the moving water to come to an abrupt halt. This sudden stop creates a high-pressure wave that travels through the pipes, resulting in the characteristic banging noise. The energy from this pressure wave can cause significant stress on the plumbing system, leading to potential damage such as burst pipes, damaged fittings, and leaks.

Causes of Water Hammer

  1. Sudden Valve Closure: Rapidly closing valves or taps are the most common cause of water hammer. The abrupt stop of water flow creates a pressure wave.
  2. High Velocity Water Flow: High flow rates increase the potential for water hammer because more kinetic energy is involved.
  3. Long Runs of Pipe: Longer lengths of pipe allow the pressure wave to build up more force as it travels.
  4. Lack of Air Chambers or Arrestors: Air chambers or water hammer arrestors can absorb the shock wave, and their absence can make water hammer more severe.

Role of Pressure Regulators in Water Hammer

Pressure regulators are devices designed to control the pressure of water entering a plumbing system. They work by reducing the high pressure from the supply line to a lower, more manageable pressure for the downstream system. While pressure regulators are intended to maintain stable pressure levels, they can sometimes contribute to water hammer in several ways:

Rapid Valve Closure

Some pressure regulators are equipped with internal valves that can close quickly in response to changes in downstream pressure. If these internal valves close too rapidly, they can create the same effect as a suddenly closed tap, causing water hammer.

  • Mechanism: When the pressure regulator detects a rise in downstream pressure, it responds by closing its internal valve to reduce the flow. If this closure happens too quickly, it can cause a pressure wave to propagate through the system, leading to water hammer.

High Flow Rates and Pressure Differential

Pressure regulators that are not properly sized for the system can lead to high flow rates and significant pressure differentials, both of which can exacerbate water hammer.

  • Mechanism: An undersized pressure regulator may restrict the flow too much, causing a high-pressure differential across the valve. When the downstream demand decreases suddenly, the regulator might not be able to adjust quickly enough, leading to a pressure surge.

System Design and Installation Issues

Improper installation or design of the pressure regulator and the plumbing system can contribute to water hammer. Factors such as the placement of the regulator, the type of pipes used, and the presence of air chambers or arrestors all play a role.

  • Mechanism: If the pressure regulator is installed too close to fixtures that are frequently turned on and off, the chances of water hammer increase. Additionally, if air chambers or arrestors are not installed near the regulator, there will be nothing to absorb the pressure wave.

Mitigating Water Hammer Caused by Pressure Regulators

To prevent or mitigate water hammer caused by pressure regulators, several strategies can be employed:

Proper Sizing of Pressure Regulators

Ensuring that the pressure regulator is properly sized for the system is crucial. An appropriately sized regulator will handle the flow rates and pressure differentials without causing excessive turbulence or rapid valve closure.

  • Solution: Consult with a plumbing professional or refer to manufacturer guidelines to select a pressure regulator that matches the specifications of your plumbing system.

Gradual Valve Closure

Some pressure regulators come with adjustable settings for the speed at which the internal valve closes. Slowing down the valve closure can help reduce the likelihood of water hammer.

  • Solution: If your pressure regulator has an adjustable closure rate, set it to close more gradually. This will help minimize the abrupt changes in flow that cause water hammer.

Installation of Water Hammer Arrestors

Water hammer arrestors are devices specifically designed to absorb the shock wave caused by water hammer. Installing arrestors near pressure regulators and other critical points in the plumbing system can significantly reduce the occurrence of water hammer.

  • Solution: Install water hammer arrestors at key locations, such as near the pressure regulator, washing machines, dishwashers, and other appliances that frequently stop and start water flow.

Adding Air Chambers

Air chambers act as cushions that absorb the pressure wave created by water hammer. They are simple vertical pipes installed near fixtures that can help mitigate the impact of sudden water flow changes.

  • Solution: Ensure that air chambers are installed and properly maintained. Over time, air can dissolve into the water, so periodically draining the plumbing system to refill the air chambers may be necessary.

System Design Considerations

Proper system design can help mitigate water hammer. This includes ensuring that pipes are adequately supported and that the pressure regulator is installed at an appropriate distance from fixtures and appliances.

  • Solution: When designing or retrofitting a plumbing system, consider the placement of pressure regulators, the type of pipes used, and the inclusion of adequate support and cushioning measures like arrestors and air chambers.

Case Studies and Practical Examples

Residential Plumbing System

In a residential setting, a homeowner reported loud banging noises whenever the washing machine completed its cycle. Upon inspection, it was found that the pressure regulator was installed too close to the washing machine and did not have any water hammer arrestors.

  • Solution: The pressure regulator was adjusted for a slower valve closure rate, and water hammer arrestors were installed near the washing machine. The banging noises ceased, and the system operated smoothly.

Industrial Water Supply System

An industrial facility experienced frequent water hammer events after installing a new pressure regulator. The regulator was undersized for the high flow rates required by the facility.

  • Solution: The facility upgraded to a larger pressure regulator capable of handling higher flow rates. Additionally, surge tanks were installed to buffer pressure fluctuations. The incidence of water hammer was significantly reduced.


While pressure regulators are essential for maintaining stable water pressure in plumbing systems, they can sometimes contribute to water hammer if not properly sized, installed, or maintained. Understanding the mechanisms by which pressure regulators can cause water hammer is crucial for diagnosing and resolving these issues.

By ensuring proper sizing, adjusting valve closure rates, and incorporating water hammer arrestors and air chambers, you can effectively mitigate the risk of water hammer in your plumbing system. Regular maintenance and system design considerations also play a vital role in preventing hydraulic shocks and ensuring the long-term reliability and safety of your water supply system.

Ultimately, addressing water hammer caused by pressure regulators requires a combination of careful planning, appropriate equipment selection, and proactive maintenance. By taking these steps, you can protect your plumbing system from the damaging effects of water hammer and enjoy a quieter, more efficient operation.

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Hi, I’m Sophia Wang, the Marketing manager of, I’ve been working in this factory 8 years now, and the purpose of this article is to share with you the knowledge related to pressure control valves from a Chinese supplier’s perspective.

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