What is a non-slam axial flow check valve and how does it function in a fluid system?
Non-slam check valves are check valves used to prevent reverse fluid flow. Also, these valves are meant to eliminate or reduce water hammer and their associated effects.
A water hammer is a high-pressure shock wave that happens when the fluid flow stops abruptly because of a pump or valve closing quickly in a piping system. When water hammer happens, the fluid flow reversal causes high stress on the piping system which endangers its structural integrity and may cause damage or rupture. Non-slam check valves are used to prevent water hammers and ensure fluid flows in one direction only. Non slam check valve manufacturers produce this valve without a handle or actuator but it works mechanically to stop the fluid flow from reversing
What are the primary applications of non-slam axial flow check valves in various industries?
- Non-slam check valves are used in chemical industries.
- These valves are used in the foods and beverages industries.
- They are used in pharmaceutical applications.
- These valves are used to prevent the backflow of water or steam in boiler applications.
- They are used to prevent water contamination in the freshwater supply.
- These valves are used in the oil and gas industries.
- They are used in wastewater treatment.
How does a non-slam axial flow check valve differ from traditional check valves?
Comparing different types of Non-Slam Check Valves, each has its unique advantages and disadvantages:
- Axial Check Valves: Advantages of these valves include their ability to provide non-turbulent, smooth flow, which reduces the potential for water hammer. They also typically have a lower pressure drop than other valve types. However, one disadvantage is that they can be more expensive due to their specialized design.
- Nozzle Check Valves: These are beneficial for their automatic operation and slow closing speed, which helps prevent water hammer. Their short pattern design also saves space. A disadvantage could be their limited suitability for low flow applications as the flow velocity might not be sufficient to fully open the valve.
- In-Line Piston Check Valves: Their compact design and ability to operate in any orientation make them ideal for systems where space is limited. However, they may not be suitable for high-velocity flow applications as the rapid movement of the piston could lead to wear and tear over time.
- Venturi Check Valves: Advantages include their suitability for high-pressure differential applications due to their ability to minimize pressure drop. They also enhance the speed of the fluid through the valve, reducing backflow. However, they may not be the best choice for low-pressure systems as the pressure might not be sufficient to fully utilize the venturi effect.
- Swing Check Valves with Dashpots: The addition of dashpots allows these valves to control the closing speed of the disc, achieving a non-slam operation. This makes them versatile and adaptable to various applications. However, the additional components may lead to increased maintenance requirements.
In conclusion, the choice of the right type of Non-Slam Check Valve depends on the specific requirements of the application, such as flow rates, pressure levels, space availability, and maintenance considerations.
What are the main components of a non-slam axial flow check valve and their functions?
Non-Slam Check Valves are comprised of several key components that collectively contribute to their functionality and performance. At the core of these valves is a disc or plate, which is the primary component responsible for controlling the flow of fluid. This disc is designed to move freely within the valve body under the influence of fluid flow. In conditions of forward flow, the fluid pressure pushes the disc off its seat, allowing the fluid to pass through. When the flow begins to reverse, the disc descends or swings back onto its seat, blocking the reverse flow. The disc’s movement is delicately calibrated to ensure it closes just before the reverse flow reaches the valve, thereby preventing water hammer. The seat of the valve, against which the disc rests in closed position, is another critical component. It is typically designed to provide a tight seal when the valve is closed. The valve body houses these internal components and connects the valve to the rest of the system. Depending on the specific type of Non-Slam Check Valve, there may be additional components such as hinges or trunnions (in Swing Check Valves) or a dashpot mechanism to control the closing speed of the disc. The structure and design of Non-Slam Check Valves aim to provide efficient and safe flow control, minimizing the risk of system damage due to water hammer.
How does the design of a non-slam axial flow check valve prevent water hammer and reverse flow?
Water hammer is a common issue with traditional check valves. A traditional swing check valve requires gravity and flow reversal to fully close. When this happens, the flap on the valve slams shut, abruptly stopping the flow, and allowing the effects of water hammer to ensue. Pressure surges set up potential for ruptured pipes and components, excessive noise and vibration, and damages to pipe supports and flanges.
There are a couple of ways this can be prevented, however. One way is to make sure your check valves are properly sized. In a post we wrote earlier this year, we discussed how improper sizing and selection can attribute to poor performance. Another way to prevent water hammer is to seek out a check valve with non-slam features.
Non-slam check valves don’t rely on flow reversal or gravity to close. Instead, the valve is closed by a spring. As the forward velocity of the fluid slows, the spring closes the valve. The closing disc has a much shorter distance to travel, compared to a swing check valve, and the valve is closed before the fluid has a chance to reverse and cause the water hammer.
What materials are typically used in the construction of non-slam axial flow check valves to ensure durability and performance?
Axial flow check valves are commonly made from steel and many other high alloys and are designed for high pressure classes and meet the rigorous standards of all industrial applications including both nuclear and non-nuclear power plants, refineries, oil fields, chemical plants and many other applications.
How does the flow rate and pressure affect the operation of a non-slam axial flow check valve?
Non-slam check valves are designed specifically for use in these situations. As their name implies, these valves close without slamming, meaning no excess pressure spikes are created. The disc of a non-slam check valve has an internal spring opposing the opening fluid flow pressure.
What are the common maintenance procedures for non-slam axial flow check valves to ensure they function correctly?
Maintenance and operation are key to ensuring the longevity and optimal performance of any device, including Non-Slam Check Valves. Regular inspection is the first step in maintaining these valves. This involves checking for leaks, wear and tear, or any signs of corrosion. Any issues identified should be addressed promptly to prevent further damage. It’s also crucial to clean the valves regularly to remove any debris that could obstruct the fluid flow and affect the valve’s performance. When operating the valve, make sure to follow the manufacturer’s instructions. Incorrect operation can lead to premature wear and tear or even damage the valve. Lubrication is another important aspect of maintenance. Regularly lubricating the moving parts of the valve can help reduce friction, prevent wear, and extend the valve’s lifespan. Additionally, when not in use, valves should be stored in a dry and clean environment to prevent rust and corrosion. Finally, it’s recommended to keep a record of all maintenance activities. This can help you track the valve’s condition over time, predict potential issues, and plan preventive maintenance accordingly. By following these tips, you can help ensure the longevity and optimal performance of your Non-Slam Check Valves.
How can non-slam axial flow check valves be tested to ensure they are working properly and within specifications?
Non-Slam Check Valves are engineered to close gradually, ensuring a smooth transition and avoiding the creation of a shock wave. These valves operate based on the flow conditions in the system, opening when the fluid flows in the forward direction and closing when it starts to reverse.
What are the common failure modes of non-slam axial flow check valves and how can they be mitigated?
The valve’s flow direction is another point to check, as Non-Slam Check Valves are designed to allow flow in one direction only. You should also look at the valve’s opening and closing speed to prevent water hammer, a common issue that can cause significant damage to the system.
What safety considerations should be taken into account when installing and operating non-slam axial flow check valves?
- Correct Orientation: Always install the valve with its flow direction in line with the arrow on the valve body. Incorrect orientation could cause malfunction or failure.
- Alignment: To align properly with a pipeline, positioning of the valve is necessary. Misalignment can lead to untimely wear and tear on the valve thereby resulting leakage.
- Support: It is important that adequate means of support are provided to such pipes so as not to burden these devices with their weight. This will help avoid straining them by ensuring a stable fitting.
- Cleanliness: Make sure pipe lines are clean and free from any debris before installing them. Solids can impair valve seats and discs hence causing operational problems.
- Tightening: Follow-up on manufacturer’s recommendations regarding bolt tightening torque for valves. Failure to do this may result in a leaking valve due to either too tight or very loose installation bolts.
- Gaskets and Seals: Use appropriate gaskets and seals compatible with the fluid being handled by the valve .This will ensure sealing thus prevent leaks from occurring.
How does the installation position and orientation of a non-slam axial flow check valve impact its performance and effectiveness?
The components of the piping system include pumps, valves, compressors, elbows, bends, and reducers, and it will cause turbulence in the flow stream. In case to improve the service time of an axial flow check valve, you need to install it in accordance with best industrial practice, which means we need to keep enough distance from the turbulence source that makes the valve is in fully developed flow.
Horizontal Flow Installation
Vertical Flow Installation
Non-slam axial flow checks are also suitable for vertical flow up and down. But it requires more process conditions for selection and sizing.
To ensure turbulence is minimized, the axial flow check valve needs to be at least 4 diameters distance to downstream of a reducer or expander, so that to make sure flow at the valve is fully developed.
To avoid causing choked flow that makes the valve only partially open, we should install an axial check valve at least 2 diameters distance to upstream of a reducer or bend.