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What are the Different Types of Check Valves?
Check valves are a safety device often implemented in fluid and gas assemblies for ensuring that all materials only move in one direction through the system. As fluids are pressurized, they will pass through the valve by first entering the inlet, and then will be forced through the outlet for their exit. Based on the various check valve designs found across common types, all serve to provide uninterrupted flow until pressure is lost or the pump is shut down at which time they will then prevent any fluids or gasses from moving back through the check valve. In this blog, we will provide a brief overview of the common types of check valves, allowing you to know how such components provide their one-way flow operations.
Check valves can be found in countless applications ranging from industrial to commercial systems. For gardens, a check valve can be as simple as ensuring that water and fertilizers are managed in their flow. For a more demanding application such as aircraft, check valves manage hydraulic fluids, fuel, and other materials that are paramount to the overall functionality of the hydraulic system, engine, and other apparatuses. While each check valve will remain similar in their ability to prevent backflow, different types will provide for varying flow rates, media, gravity and temperatures, pressures, velocities of flow, and line sizes.
Ball Check Valve
The ball check valve is a type in which a ball is used to block the flow of fluids. Often utilizing springs for mechanical movement, the ball will be lifted as fluid pressure forces its way through the assembly so that flow is uninterrupted. With the design of the ball check valve, a loss in pressure will cause the ball to lower and seal off the flow with enough force that fluids cannot backtrack through the system.
Butterfly Valve
The butterfly valve is another type that features halves of a disk that can open towards the centerline when met with pressurized fluids. Due to the direction that they open, reverse flow will seal the pipe as the disc halves are held closed with force. As the butterfly check valve has quiet operation, they are often used for HVAC systems.
Lift Check Valve
Lift check valves will allow for fluids to enter below the seat of the valve, and pressure causes a disk or ball to be raised from its seat for flow to occur. As pressure drops or stops altogether, the ball or disk is forced downwards to a closed position through gravity. With their method of operation, the lift check valve is most often used for systems that feature high flow and velocity rates.
Stop Check Valve
Stop check valves can come in the form of various check valve types, and their difference lies in the fact that they will often have a lever, stem, handwheel, or other component that is capable of closing off the valve from the flow of fluids. With this construction, the disc is prevented from opening for increased stopping capabilities.
Diaphragm Check Valve
The diaphragm check valve is one that utilizes either a diaphragm or disk that is placed between the inlet port and exit port. Settled in the seating area of the assembly, an opening is located in the center so that fluids may move unimpeded during standard flow. When backflow occurs, the rubber disk will cover the opening of the seal, ensuring that the inlet is closed.
Foot Valve
The foot valve is one that may be located at the bottom of a pipe that is connected to a pump. Similar to ball check valves, they utilize a screen in order to block any debris as fluids move. When pumps are shut off, water may move through the pipe due to gravity, but the foot check valve will impede its flow as weight closes the opening.
Swing Check Valve
The Swing check valve is one in which the disk is placed out of the flow of fluids, and it swings to close the valve at a slow pace. When reverse flow meets the disk, it will close it with force to generate a water hammer. Swing valves are most commonly used for applications with a high percentage of solids.
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