Types of Surge Vessels that represent a solution to water hammer

There are multiple types of Surge Vessels that represent the ideal solution to water hammer and their risks. In a previous article, we mentioned the compressed surge vessel. We have dedicated this article to explaining two other types of pressure vessels because of their importance in protecting against the risks of water hammers.

Read more about The risks of water hammer on pipelines in water treatment plants

Video explaining in a simplified manner why water hammer occurs

Surge Vessels type options

The purpose of a shock control tank or pressure vessel is to provide a predetermined amount of gas (usually air) and liquid (usually water) at the moment of a shock event. The air and water volumes are usually calculated by a hydraulic study. That examines the hydraulics of the entire tubular system, are chosen to relieve transient pressures during a shock event. When low pressures occur in the connected pipes, the air in the tank expands and forces water into the system to relieve the low pressures, and when high pressures occur, the air in the tank compresses and acts as a shock absorber to reduce the volume of high pressures.

If the air and water volumes in the tank are not correct at the time of the shock, excessive high and low pressures will occur which can cause the pipes to burst or collapse.

To ensure that the air and water volumes are correct, shock tanks are often equipped with a control system that maintains the air and water volumes at the required levels within the tank at all times when the system is in operation. There are several different ways to provide such a system.

Compressed Type Surge Vessel

In this type, the compressed air interacts directly with the water inside the vessel, eliminating the need for a diaphragm or bladder. This direct contact allows for immediate response to pressure changes, enhancing the system’s ability to manage sudden surges. Once activated, the surge vessel operates automatically, responding to pressure fluctuations by depressurizing as needed and refilling as the system stabilizes. The vessel’s robust construction, typically made of high-quality materials, ensures durability and longevity, even under high-pressure conditions.

This pressure vessel is ideal for applications that require reliable and effective protection against water hammer. The design ensures minimal maintenance while providing maximum protection, making it a cost-effective solution for long-term use.

We’ve covered it in more detail in this article.

Bladder Type Surge Vessel

A hydraulic pressure vessel, expansion tank or Blaader type is designed to manage pressure surges using an internal rubber bladder. This innovative approach ensures that the flexibility of the vessel effectively pushes water back into the system after the pump has travelled. An important aspect of the efficiency of this system is the accurate calculation of the pre-charge pressure, which is vital for optimum performance.

By preventing contact between the compressed air and the water, the vessel eliminates the risk of air dissolving in the water. This design feature eliminates the need for a permanent regulating system, such as a compressor, thus simplifying the system and reducing maintenance requirements.

Once the vessel is pre-charged and properly primed, it operates automatically. The vessel is depressurized as needed and refilled with return waves until it naturally reaches steady state equilibrium. This automatic process ensures consistent performance and reliability in controlling surges.

The internal bladder is typically made of high-tensile rubber, which may include reinforcements. It is available in a variety of materials such as neoprene, nitrile (Buna-N) or Hypalon rubber. The bladder is designed to expand to fit the entire vessel and is securely attached with a lip at the top. Specifically designed to fit the specific vessel details provided by the customer.

This advanced design not only ensures effective surge control. But also extends the life of the receptacle and associated system components.

Dip Tube Type Surge Vessel

It is an advanced solution designed to operate without the need for an air compressor or internal bladder, providing a more streamlined and reliable approach to managing pressure surges. This innovative vessel features an air inlet valve and an internal dip tube, ensuring precise control of the air charge for optimal performance in various applications.

During normal operation, the liquid level remains above the bottom of the dip tube. This level dynamically adjusts to accommodate surge events, effectively absorbing and dissipating pressure fluctuations. In the event of air being sucked or lost from the system, the air inlet valve automatically opens to replenish the air charge, maintaining consistent functionality and system stability.

One of the key advantages of the Dip-Tube pressure vessel is its compact and economical design. By eliminating the need for additional components such as air compressors, the vessel reduces overall volume requirements and associated costs. This efficiency does not compromise performance, as the vessel is designed to maintain system pressure and enhance the reliability of the entire system.

To ensure proper operation, it is essential to have accurate piping geometry and flawless performance of all associated equipment. This attention to detail ensures that the surge vessel operates at maximum efficiency, providing robust protection against pressure surges and extending the life of system components.

Features:

• Bladder-free design: No bladder issues, ensuring reliability.
• Economical: No air compressor is required.
• Advanced air control: Uses an air inlet valve.
• Dynamic response: Efficiently manages liquid level during surges.
• Fail-safe mechanism: Automatically replenishes air charge.
• The dip tube pressure vessel is ideal for a wide range of applications.

How to choose the right type of Surge Vessels

Now that we have explained the role that Surge Vessels play in containing and managing various materials. Under varying pressure and temperature conditions, choosing the right pressure vessel is critical to the success and safety of your operations.

1. Understanding process requirements: This involves identifying the unique needs and challenges your business presents.
2. Regulatory compliance: Ensuring compliance with industry standards and regulations is non-negotiable when it comes to pressure vessels. Legal obligations and requirements must also be understood.
3. Material Selection: Choosing the right material for a pressure vessel is a critical decision. It directly affects its performance, durability, and longevity. Factors that influence material selection include:
   • Consider the materials the vessel will come into contact with and their potential to corrode or react with the vessel material. Stainless steel, carbon steel, and specialty alloys offer varying degrees of corrosion resistance.
   • Design and Construction: The design and construction of your pressure vessel must meet your process requirements and safety considerations:
   • Shape and Size: The shape and size of the vessel should be optimized for your specific application. Such as space constraints and fluid dynamics.
   • Thickness Calculations.
   • Reinforcements and Bracing: Depending on the size and shape of the vessel, additional reinforcements. Support structures may be necessary for stability and safety.
4. Safety Features and Testing: Safety should be a top priority in pressure vessel selection. Incorporating safety features and careful testing is vital to preventing accidents and ensuring reliability.
5. Emergency Shutdown Systems: Implementing emergency shutdown systems can quickly isolate a problem in the event of an emergency.
6. Long-Term Maintenance and Durability: The longevity of your pressure vessel depends on proper maintenance and care.
7. Cost Analysis: A thorough cost analysis is critical to understanding the financial implications of your choice.