Check Valve Selection 101: Types & Applications

Check Valve Selection 101: Types & Applications

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.

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Choosing the correct check valve for a specific application is essential to achieving optimal performance, reliability, and service life. In this guide, we will explore various check valve types and applications to help you decide on the best option for your project.

Important Check Valve Selection Criteria

When selecting a check valve for an application, consider the following:

• Initial Costs: Consider the cost of the valve and any installation costs associated with it.
• Maintenance Costs: Maintenance and repair costs can vary depending on valve complexity. Improper or oversized check valves can significantly increase life cycle maintenance costs.
• Head Loss and Energy Costs: Head loss is dictated by the internal valve design and the degree of opening. Restrictions within the valve can lead to increased head loss, resulting in higher energy costs.
• Non-Slam Characteristics: Proper valve selection is critical in preventing water hammer and slamming during operation. Select a check valve with closing characteristics compatible with your pumping system dynamics.
• Fluid Compatibility: Choose a valve suitable for the fluid's viscosity, sediment, and particles passing through it.
• Sealing Ability: Ensure the valve you select provides the necessary sealing, be it gas-tight, bubble-tight, or drop-tight sealing.
• Flow Characteristics: Each check valve has unique flow characteristics. Matching these to your requirements can minimize reverse flow or surges during sudden pump shutdowns.
• Valve Size and Pressure Rating: Valves come in various sizes and pressure classes. Make sure to select one that matches your system's flow rate and can withstand the operating pressure. Incorrect sizing can lead to inefficiencies or system failures.
• Materials Selection: Consider the compatibility of the fluid type, temperature, and corrosiveness when choosing valve materials to ensure reliability.
• Installation Orientation: Consider where and how you will install the check valve; not all can be installed horizontally or vertically.
• Application Considerations: Different applications have unique requirements, such as sanitary standards for food or fire safety regulations for oil and gas. Ensure your check valve meets these specific industry standards.

Types of Check Valves and Their Applications

Several types of check valves are designed for particular uses. Common types include lift, swing, and ball check valves.

Lift Check Valves

Lift check valves are economical, automatic valves with no external moving parts ensuring reliable operation. Types include nozzle check valves, in-line check valves, and piston check valves. They feature a closure mechanism, typically a disc that lifts off the valve seat when subjected to inlet pressure, allowing fluid to flow through. A spring or gravity returns the disc to the seat when upstream pressure drops, stopping fluid flow. DFT® check valves can be installed horizontally, vertically up, or vertically down and are particularly used in backflow prevention applications.

Swing Check Valves

Swing check valves are among the most common due to their low cost. Operating entirely on flow pressure and gravity, these valves rely on flow direction change to close, making them suitable only for horizontal or vertical "up" lines and susceptible to slamming and water hammer. Common applications include wastewater, sewage systems, and consistent-flow water pumping.

Ball Check Valves

Ball check valves are simple with a spherical ball as the closing member and no external components. Some designs are spring-loaded, while others rely on reverse flow to seat the ball. Their simplicity makes them ideal for many uses such as liquid or gel mini-pump dispensers, hydraulic systems, and sprayers.

Contact Our Experts for Your Check Valve Needs

With various check valve types available, it's crucial to consider your fluid system's specific needs when selecting the best check valve. Factors include cost, fluid compatibility, sealing ability, non-slam characteristics, and installation orientation. DFT® manufactures top-quality silent check valves and severe service control valves for critical industries, including oil and gas, food and beverage, and wastewater processing. Our check valves are known for eliminating and preventing water hammer issues in diverse fluid systems.

Browse our catalog of check valves to find the best product for your system. Additionally, you can download our eBook, Design for Flexibility: Key Considerations to Make When Designing Fluid or Gas Flow Systems. Contact us or request a quote to speak with a specialist about your check valve needs.