Check valves, sometimes called non-return valves, are valves with two openings or ports that allow fluid flow in only one direction. Fluid enters through one port and exits the valve through the other. Industrial fluid systems in power plants, chemical plants, water and wastewater treatment facilities, oil fields, refinery applications, and other industries rely on check valves to prevent fluid flow back to the source. For instance, check valves are often used to transfer fuel and an oxidizer in separate lines to a mixing vessel without the fuel or oxidizer flowing back into the initial gas or oxidizer cylinders.
For more information, please visit Huade Hydraulic.
Selecting the right check valve for a specific application is essential to achieving optimal performance, reliability, and service life. Here, we will explore the various check valve types and applications to help you decide on the best option for your project.
When selecting a check valve for an application, consider the following:
There are several types of check valves designed for distinct applications. Some of the most common check valves include lift, swing, and ball check valves.
Lift check valves are economical, automatic valves with no external moving parts for reliable operation. Specific types of lift check valves include nozzle check valves, in-line check valves, and piston check valves. The main closure mechanism in a lift check valve is typically a disc that lifts off the valve seat when subject to inlet pressure, allowing normal fluid flow past the disc and seat, then through the outlet port. The motion of the disc is guided in a straight line, so the valve can later reseat properly. A spring or gravity moves the disc back into the seat when the upstream fluid pressure drops, stopping the fluid flow. DFT® check valves can be installed in any orientation: horizontal, vertical flow up, or vertical flow down. These types of valves are commonly found in applications where backflow prevention is critical.
Swing check valves are one of the most common types of check valves due to their low cost. Because the valve operates entirely from flow pressure and gravity, it relies on the change of flow direction to close. This means swing check valves can only be used for horizontal or vertical 'up' lines and are very susceptible to slamming and water hammer. These types of valves are commonly used in wastewater, sewage systems, and predictable flow water pumping applications.
Ball check valves are often very small and simple in that the closing member is a spherical ball and the valve has no external components. The rotation of the ball during operation prevents particles from getting stuck on the ball. Some designs are spring-loaded and some do not have springs, instead relying on reverse flow to move the ball to the seat for sealing. Ball check valves are used in many applications and are often found in liquid or gel mini-pump dispenser spigots, hydraulic systems, and sprayer devices.
With many check valve types to suit various applications, it is vital to consider your fluid system's needs when selecting the best check valve. Some of these deciding factors include cost, fluid compatibility, sealing, non-slam characteristics, and installation orientation. DFT® manufactures world-class silent check valves and severe service control valves for critical industries, from oil and gas to food and beverage to wastewater processing. We pride ourselves on collaborating closely with customers to solve their unique challenges. Our check valves are world-renowned for eliminating or preventing water hammer issues in diverse fluid systems.
A hydraulic check valve, also known as non-return valve (NRV), is a mechanical device designed to allow fluid (typically a liquid) to flow in one direction and prevent reverse flow; it plays a crucial role in hydraulic systems to maintain the direction of fluid movement or to control pressure or flow rate.
Generally check valves are automatically operated; human intervention or any external control system is not required.
Are you interested in learning more about Electro hydraulic control valve? Contact us today to secure an expert consultation!
Check valves have a body (often cylindrical) with inlet and outlet ports for fluid to enter and exit; inside there's a movable element (often a poppet, more rarely a ball) whose function is to block the flow in the reverse direction. When fluid flows in the desired direction, its pressure forces the poppet away from the seat, allowing the fluid to pass around the valve. Vice versa, if there's an attempt at reverse flow, pressure from the fluid pushes the poppet against its seat. This seals off the passage and prevents fluid from flowing backward. In most cases, a spring helps to close the poppet quickly and effectively when the flow direction changes, preventing backflow.
Check valves must necessarily be installed in the correct orientation; in fact, they are designed to allow flow in one specific direction, so improper installation will result in valves not functioning as expected. When fluid flows in the desired direction, the valve opens, and when there's an attempt at reverse flow, the valve closes to prevent backflow. This design is crucial for maintaining the efficiency and safety of hydraulic systems by preventing unintended fluid movement in the wrong direction.
Check valves usually have a straight profile and one single body or two screwed semi-bodies. Inlet and outlet threads can be female or male type.
A special category is represented by parts where an orifice machined on the poppet allows controlled leakage of fluid in the direction in which the flow is normally prevented by the closure of the valve. This design trick makes check valves equipped with an orifice a flow control tool. There are also three-way valves (or 'shuttle' valves), which have the characteristic of conveying to the return line of the circuit the greater of the pressures of the two delivery lines.
Understanding the nuances between NRV (non-return valves) and conventional check valves is crucial in hydraulic systems. While often used interchangeably, these terms essentially refer to the same component. The distinctions lie in regional preferences and industry jargon. In essence, whether you call it an NRV or a check valve, the functionality remains consistent, ensuring unidirectional fluid flow and preventing backflow. Clearing up any confusion between the terms is vital for precise communication within the hydraulic engineering realm.
Prevent Backflow: Explore Our High-Quality Hydraulic Check ValvesMaintain reliable flow control and prevent backflow with Faster's high-performance hydraulic check valves, designed for durability and efficiency.
Explore SolutionsIn hydraulic systems, the choice of materials for hydraulic check valves is paramount, with carbon and stainless steel emerging as the most commonly utilized raw materials. These robust materials not only provide durability but also ensure the reliability and longevity of the check valves. The selection of carbon or stainless steel depends on the specific requirements of the hydraulic circuit. These materials play a pivotal role in maintaining the structural integrity of the check valves, contributing to their effectiveness in controlling fluid flow and preventing backflow. A careful consideration of these material options is essential in ensuring the optimal performance and longevity of hydraulic check valves in diverse applications.
In the realm of hydraulic systems, the symbolic language of hydraulic check valves is conveyed through a stamped valve symbol on the external body. This symbol serves as a visual identifier, facilitating easy recognition of the check valve among other hydraulic components, and greatly helps to avoid installation mistakes as it shows the closing direction of the valve. This simplistic yet informative feature aids in the swift and accurate identification of check valves in complex hydraulic circuits. It is a valuable element for engineers and maintenance personnel, streamlining troubleshooting and ensuring efficient operation. The presence of a clear and standardized valve symbol enhances the overall functionality and usability of hydraulic systems, promoting ease of maintenance and optimal performance.
As with all complex components in a hydraulic circuit, it's possible to experience issues with check valves too, the most common being the stuck of poppet in open or closed position, unexpected leaks, chattering or the valve not opening at the set pressure. Choosing products suiting the circuit specifications, installing them properly and performing some periodical maintenance can help prevent many of these issues from occurring in the first place.
With a long experience of design and production, Faster is the ideal supplier for top-quality check valves. Every day we deliver all types of valves (ball-type, poppet-type, shuttle-type, etc.) to our customers to allow control of directional flow, or pressure, or flow rate for a wide range of applications and for different markets.