velocity cap

The Velocity Cap: A Boon for Fish in Offshore Water Intake Systems

Offshore water intake structures are essential for various industrial and municipal purposes, providing a steady supply of water. However, these structures pose a significant threat to aquatic life, particularly fish, due to the powerful currents they generate. To mitigate this threat, engineers have developed a clever solution: the velocity cap.

The Problem: Entrainment and Mortality

The primary concern with offshore water intakes is the phenomenon known as entrainment, where fish and other aquatic organisms are swept into the intake pipe along with the water. This often leads to mortality, as the organisms are unable to survive the rapid change in pressure and flow conditions. The severity of entrainment is directly related to the intake velocity, the speed at which water flows into the intake.

The Solution: The Velocity Cap

The velocity cap is a horizontal structure, usually a flat plate or a series of baffles, installed at the top of a vertical intake pipe. Its purpose is to reduce the intake velocity by effectively creating a horizontal inflow, rather than a vertical one. This change in flow direction significantly decreases the likelihood of fish being entrained and swept into the pipe.

How it Works:

The velocity cap operates on a simple principle. By creating a horizontal flow, the cap forces water to flow around the intake pipe instead of directly into it. This reduces the vertical velocity component, making it less likely for fish to be swept into the intake. Additionally, the cap often features screens or mesh that further minimize the chances of small fish being entrained.

Benefits of Using a Velocity Cap:

• Reduced Entrainment: The primary benefit of the velocity cap is its ability to significantly reduce fish entrainment and associated mortality.
• Increased Water Intake Efficiency: By ensuring a smoother flow of water, the velocity cap can actually improve the efficiency of the water intake system.
• Environmental Responsibility: The velocity cap is a sustainable and responsible solution for minimizing the impact of water intake structures on aquatic ecosystems.

Applications:

The velocity cap has become a standard component in many offshore water intake systems, particularly those designed for power plants, desalination facilities, and industrial processes. It is a cost-effective and environmentally friendly solution that can significantly reduce the risks of fish entrainment, ensuring a more sustainable and responsible approach to water intake.

Conclusion:

The velocity cap is a crucial element in the design of responsible offshore water intake systems. By reducing the intake velocity and creating a more fish-friendly flow environment, the velocity cap helps protect aquatic life, contributing to a healthier and more balanced ecosystem. As we continue to rely on these systems for water supply, incorporating the velocity cap into their design is a critical step towards responsible and sustainable water management.