Reliable fluid control requires integrating different valves, each ensuring proper directional and flow rate of service fluids. Check valves are predominant in fluid flow applications and are vital for regulating fluid flow in one direction. They prevent reverse fluid flow (backflow), mitigating the negative impacts from the sudden reversal of fluid flow direction.

A check valve might not be a complex component, but its effect - financially and safety-wise, is enormous. Think of the check valve as a defense mechanism against expensive equipment damage that can cause extended process downtime or extreme safety problems. A check valve in a fluid pipeline has the following functions:

• Keep fluids flowing in a specific direction, preventing contamination and flow inefficiencies.
• Protecting process equipment, including pumps or compressors.
• Maintaining fluid pressure to avoid sudden surges and losses in pipelines.
• Protecting pipelines from water hammers due to sudden pressure surges that can damage pipelines and equipment.
• Maximize safety by preventing the unregulated mixing of chemicals or hazardous substances in industrial processes.

Check valves are automatic flow control devices relying on service fluid pressure to open or close. They do not require external intervention, say human or actuator-reliant operation. Check valves come in different sizes and designs, each tailored for specific pipe orientations. Broadly, the common check valves are:

• Swing check valves
• Vertical check valves

What are the structural, functional and operational differences between these valves categories? Let us explore them further in the sections below.

What is a Swing Check Valve and How Does It Work?

A swing check valve contains a disc/flapper connected to a hinge (pivot) on which it tilts to open or close, depending on the fluid pressure conditions. The flapper (disc) pivots around the hinge, assuming a horizontal position when the fluid attains a specific flow rate and pressure, keeping the valve open and allowing fluid to pass through. The minimum or ideal pressure for the valve to open is also called the cracking pressure of the check valve.

When the flow rate changes and the fluid pressure drops below the cracking pressure, the disc pivots back and rests on the valve seat. The swing valve closes once back pressure develops in the system. As the disc swings shut, so does the valve prevent reverse flow. The opening and closing sequence repeats, responding to system changes.

Various swing check valve disc and seat designs exist, each providing unique performance characteristics responding to fluid media physical and chemical characteristics, upstream pressure requirements and system-specific fluid flow needs. The variations of swing check valves are:

• Top-hinged check valve - the pivot (hinge) is on the top part of the valve body. At an open position, the flapper rests horizontally against the top of the valve body.

 

Top-hinged swing check valve (Part 2 is the flapper/disc, Part 3&4 is the pivot/hinge)

• Tilting disc swing check valve - this swing valve has a central pivot. When the cracking pressure is achieved, the flapper tilts horizontally and remains in the path of the flowing fluid. The tilting disc swing valve opens and closes faster and has a lower cracking pressure limit than the top-hinged valve type, making them ideal for backflow prevention in pipelines with low flow rates.

Swing check valves are suitable for horizontal pipelines. They can also handle high fluid flow rates since they exert minimal flow resistance to the service fluids. The low resistance to fluid flow implies that one can achieve better fluid flow efficiencies. Swing check valves are available in larger sizes compared to their vertical-type counterparts.

Swing check valves sometimes close slowly. The slow closing time makes the valve more susceptible to water hammers, particularly if the valve is in a high-velocity fluid application.

Practical applications of swing-type check valves are:

• Preventing backflow, which can cause contamination, in water treatment plants. They are suitable for these applications as they are available in large sizes and can prevent backflow in large-diameter pipelines common in water treatment plants.
• Stopping reverse flow in pump discharge systems, preventing backflow when process pumps stop.
• Maintaining directional fluid flow in expansive irrigation pipelines in the agricultural sector.
• Managing directional flow of dirty water in wastewater management plants.

What is a Vertical Check Valve and How Does It Work?

Vertical check valves, as the name suggests, are designed for vertically oriented pipelines. It is a non-return valve, allowing fluids to flow in the upward direction only. The valve contains a disc that opens or closes when the pressure of forward-flowing fluid reaches the designed cracking pressure. The disc will close and rest on the valve seat when fluids lose forward pressure and fluid flow reverses.

Some vertical check valves have spring-loaded designs. The springs compress under the right fluid pressure, allowing fluids to pass through the valve. The valve closure mechanism (disc) rests on the valve seat whenever fluid flow stops. Vertical check valves also prevent fluid flow when the gravity is greater than the force due to the forward fluid flow. In a spring-loaded vertical check valve, the spring decompresses and pushes the disc back onto its seat. Generally, vertical check valves have faster closing times. Quick closure is essential for preventing water hammer, a common performance issue associated with check valves in fluid flow applications. Vertical check valves have a small and compact design compared to swing check valves. These compact designs imply the valves are suitable for installation in tight spaces in vertical pipes. They are also effective in high-pressure fluid flow applications like steam and boiler systems, compressed air systems and fire prevention pipelines.

Vertical check valves have higher resistance to fluid flow. These valves have high resistance to fluid flow since they are used in pipelines where fluids flow upwards. The fluid pressure must overcome gravitational forces and also the spring force before the closing mechanism opens.

Vertical check valves are smaller in size than the swing check valves and can be used in smaller size pipes. They are also unsuitable for viscous fluid service or for pipelines conveying fluids with suspended particles. They are more susceptible to clogging in such applications. They can also be sources of noise and vibrations in certain high-pressure applications because of their fast opening and closing characteristics.

Typical applications of vertical check valves are:

• Vertical water supply in high-rise buildings. These valves provide an effective means to regulate upward fluid flow, preventing backflow and prevention in sanitary plumbing systems.
• Unidirectional flow control of steam in industrial boiler systems. The valves prevent the backflow of condensates to critical steam applications.
• Maintaining the pressure integrity of vertical sprinkler pipelines in fire protection systems.
• Contamination protection due to backflow in cryogenic and chemical processing pipelines.
• Backflow prevention to protect pumps used in vertical fluid discharge in domestic and industrial piping systems.

Best practices for choosing check valves

Are you sifting through the Electric Solenoid Valves check valve catalog and wondering which product to choose for your application? Do not worry - below is a summary of the differences between swing type and vertical check valves to expedite your decision-making process.

Feature	Swing Check Valve	Vertical Check Valve
Pipe orientation	Horizontal	Vertical
Closing speed	Slow	Fast
Installation orientation	Horizontal	Vertical
Pipe sizes	Large pipe diameters	Smaller pipe diameters
Flow resistance	Low	High
Typical Application	Wastewater treatment	Compressed air systems

Summary of the differences between swing and vertical check valves

Some tips to ensure you choose the correct check valve for your application are:

• Select a swing check valve if the fluid application involves horizontal pipelines expected to evacuate high fluid volumes. The swing check valve is preferable for such systems because they have lower resistance to fluid flow.
• Use a vertical check valve when dealing with vertical pipelines where rapid valve closure is essential. These valves provide quick closure, which is crucial for preventing backflow and mitigating the negative impacts of water hammer in such pipelines.
• A swing check valve with a damping mechanism is preferable for horizontal pipelines prone to water hammers. Vertical check valves are not sufficient for such applications.
• Swing check valves are more suitable for pipelines converting fluids with suspended matter or debris. Vertical check valves clog faster and more frequently than their swing-type counterparts.
• Ensure the size of the check valve matches with the adjacent pipelines. Do not select an oversized or undersized check valve, as that impacts flow rates, efficiency and energy consumption of the piping system.

Additionally, we provide tips to streamline your valve selection process through our online expert chat support, email and a dedicated telephone service. You can always reach out to us.

Final words

Check valves are the go-to solution to address the detrimental effects of reverse flow in diverse piping systems. They provide uni-directional fluid control, closing faster when reverse fluid flow begins. These valves are available in different sizes, designs and trims, ensuring adequate flow control in multiple industrial fluid applications.

Understanding how each type of check valve works, its operational limitations and installation requirements ensures you can achieve the desired fluid flow performance, durability and efficiency in your fluid control system. Consult our experts at Electric Solenoid Valves if you have doubts about our products and their uses in your fluid application.

Shop swing check valves

Shop vertical check valves