Revolutionizing Fluid Power: How Coaxial Valves Enhance System Performance and Reliability
Photography courtesy of coax.
Fluid power systems—whether hydraulic or pneumatic—are the backbone of industrial automation, heavy machinery, and energy applications. However, selecting the right valve for these systems is a challenge. Conventional valves often struggle with pressure differentials, actuation speed, and durability in demanding environments.
Coaxial valve technology, originally developed in the 1960s by German engineer Gottfried Müller, has since revolutionized fluid power applications by addressing these limitations. These valves are designed for precision, speed, and reliability in systems where conventional solutions fall short. With capabilities to handle pressures up to 500 bar (7,500 psi) and cycle speeds as fast as 30 milliseconds, coaxial valves have become an integral component in modern fluid power systems.
Understanding Coaxial Valve Design and Functionality
At its core, a coaxial valve operates using an internal axially movable control tube, which either allows or diverts the flow of media. Unlike traditional valve designs that rely on multiple moving components, coaxial valves streamline their mechanism for enhanced efficiency and durability.
Key Design Features:
- Pressure Balanced: Coaxial valves do not experience the same pressure differentials as conventional valves, reducing actuation forces and improving switching consistency.
- Single Moving Part: The control tube is the only moving component, minimizing wear and increasing longevity.
- Integral Actuator: The actuator is built into the valve, eliminating external actuation mechanisms and reducing installation space.
- Versatile Actuation: Can be electromagnetically or pneumatically actuated, depending on application requirements.
By eliminating common failure points found in conventional valves, coaxial valves ensure consistent operation across a wide range of pressures and fluid types.
Key Benefits of Coaxial Valves in Fluid Power Systems
1. Pressure Balanced
Regardless of system pressure and pressure differences, the coaxial design balances forces within the valve. Whether it’s regulating vacuum or high pressure, the results are always exact and consistent. coaxial valves, unlike some conventional valves, do not require a minimum pressure differential to work.
2. High Cycle Life
The control element inside a co-axial only needs to move about 25% of the actual orifice size. Coaxial valves have historically outperformed ordinary valves by about 10 times.
3. Fast Actuation
Coaxial valves are extremely fast-acting when compared to other actuated valves, even with a highly viscous media and regardless of the pressure differential, as fast as 30 milliseconds.
4. Compact Size
All of the valve components are engineered around the axis of the flow channel, eliminating the need for an external actuator and keeping a compact profile,
5. Comparatively High Flow Rates
Coaxial valves are suitable for highly viscous fluids. The flow path is designed with minimal obstructions, which permits comparatively high flow rates with a minimal pressure loss.
Despite the valve’s compact size, the media is capable of flowing straight through the valve without any significant deviation.
6. Less Susceptible to Contamination
Even in the presence of contamination in the media, the coaxial valve design reduces valve seat wear. Coaxial valves have up to ten times the lifetime of ordinary valves, even under harshest conditions.
The straight-through flow also prevents buildup on the seat, by flushing any dirt or contaminates out of the valve.
7. Back Pressure Tight
In the closed state, the force of the spring inside the valve, forces the control tube to be positioned against the valve seat. This enables the valve to handle a reversed pressure differential.
8. Bi-Directional Flow
The valve’s design allows the medium to flow in both directions, in some cases eliminating the need for check valves elsewhere.
9. Self-Compensating for Seat Wear
While the valve is de-energized, the spring is pushing the control tube into the seat. At the same time the spring compensates for seat wear.
10. Fugitive emission free
The actuator on a coaxial valve is always integral, which eliminates stem seals. Any leakage caused by a worn out or damaged dynamic seal will be contained internally.
Applications of Coaxial Valves in the Fluid Power Industry
Due to their robust performance and adaptability, coaxial valves are widely used across various fluid power applications:
- Pneumatics & Automation: Their fast switching speeds make them ideal for robotics, packaging, and process automation.
- Hydraulics & High-Pressure Systems: Capable of handling extreme pressures, these valves are commonly found in power plants, injection molding, and hydraulic presses.
- Alternative Energy & Hydrogen Systems: Their ability to maintain tight shutoff and manage fluctuating pressures makes them ideal for hydrogen fuel cells, gas turbines, and alternative energy applications.
- Aerospace & Defense: Precision and durability are critical in aerospace applications, where coaxial valves control fuel systems, hydraulic actuators, and pneumatic controls.
- Machine Tool Industry: Used in CNC machining and fluid power-driven tooling, where reliable, fast switching is essential.
Addressing Common Fluid Power Challenges with Coaxial Valves
In fluid power applications, certain recurring challenges can significantly impact system efficiency and longevity. Coaxial valves solve many of these issues:
1. Leakage & Fugitive Emissions
Traditional valves with stem seals often experience external leaks over time. Coaxial valves, with their integral actuator design, eliminate stem seals, reducing fugitive emissions and ensuring long-term reliability.
2. Handling High-Viscosity or Contaminated Media
Many conventional valves struggle with thick or contaminated media, leading to blockages and premature wear. The straight-through flow design of coaxial valves allows them to handle a wide range of non-lubricating, abrasive, or contaminated fluids with ease.
3. Safety in High-Pressure Environments
By balancing internal pressures and eliminating excessive actuation forces, coaxial valves significantly reduce the risk of mechanical failure in high-pressure applications.
Is a Coaxial Valve the Right Choice for Your Fluid Power System?
Photography courtesy of coax.
For engineers and system designers, selecting the right valve is critical. Coaxial valves offer significant advantages in fast-acting, high-cycle, high-pressure, and space-constrained applications. If your system requires:
- Fast response times
- Bubble-tight shutoff (ANSI Class VI)
- Durability in extreme environments
- Efficient operation with low-pressure differentials
- Compact integration into complex systems
Then coaxial valve technology may be the ideal solution for your fluid power applications.
For over 60 years, coaxial valves have played a critical role in hydraulics, pneumatics, and high-performance industrial systems. By delivering high-speed actuation, long cycle life, and superior leak prevention, these valves continue to redefine reliability in the fluid power industry.
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