612 A ShenHui Building XIXIAN Road Baoan District Shenzhen 518000 Guangdong China
Cast Steel CF8M 12” 150LB RF Flange Dual Plate Check Valve
Nominal Diameter: 12”(DN200)
Bore: Full Bore
Nominal Pressure: 150LB
Material: CF8M
Operation:N/A
Design Standard: API594/API602/API6DTest/Inspection: API598
End Connection: Lug
Lug standard: ASME/ANSI B16.5
Top Flange: N/A
Invest in the Cast Steel CF8M 10" 150LB RF Flange Dual Plate Check Valve and experience unmatched performance and peace of mind. Its professional design and impeccable features make it an ideal choice for various industrial applications.
Doubel Plate Check Valve
Double plate, spring loaded design to protect gas or liquid
piping system
Industry standards:
ASME B16.1, B16.5, B16.24, B16.34, B16.47, and B31.1
Main features:
The double plate check valve has a two spring loaded plate design to open to release medium and bounce back to prevent external leakage. This effective check valve can be installed from any location, providing a tight seal and guaranteed no pressure loss. Two valve plates are fixed to the valve body along a pivot axis, and two springs are installed on the butterfly plate above the sealing surface Under the push of the medium flow pressure, the spring is pressed, forcing the butterfly plate to open. When the medium is reversed, the spring forces the valve to close Such valves can be assembled in horizontal and vertical lines. The sealing surface of the disc and seat is made of alloy steel or hard alloy. With high temperature resistance, corrosion resistance, wear resistance, long service life characteristics. The valve adopts the overall structure, simple and compact, small impact force when closing, small water hammer pressure, high reliability. The valve body adopts no stop ring and no dew point structure, and the shell sealing performance is more reliable.
Application:
Modulating service
Airport refueling
Hydrocarbon processing
Chemical/petrochemical processing
Purified gas
Steam and vacuum services
Power and utilities
Refrigeration
HVAC
Alumina refining
Ball check valve
A ball is pushed forward through a hole, clearing the way for flow. The movement of the ball compresses a spring. Flow in the opposite direction pushes a ball against the hole, preventing flow out of the hole. A spring expands to keep the ball in place. A ball check valve can be open to allow forward flow or closed to block reverse flow. It is a type of check valve where the closing part is a ball. Some ball check valves have a spring to help keep the ball closed. In designs without a spring, reverse flow is needed to move the ball towards the seat and create a seal. The inner surface of the main seats of ball check valves are tapered to guide the ball into the seat and create a secure seal when stopping reverse flow.
Ball check valves are frequently found in various devices such as mini pump dispensers, spray devices, air pumps, and refillable syringes. These valves are typically small, uncomplicated, and inexpensive. While the balls are usually made of metal, they can also be constructed from other materials, including highly durable or inert substances like sapphire. In applications involving high pressure, such as in liquid chromatography pumps, inlet and outlet ball check valves with ruby balls and sapphire seats are commonly used for their hardness and chemical resistance. Over time, these valves may wear out or develop cracks in the seat, necessitating replacement. To address this, the valves are designed to be replaceable and are often housed in a plastic body securely fitted within a metal fitting that can withstand high pressure.
A disassembled poppet check valve
There exist check valves that have a different shape for the disc, like a poppet activated by a spring, instead of a ball. It is important not to mistake ball check valves with ball valves, as they are distinct types of valves. Ball valves employ a rotating ball on a pin to regulate and control the flow, serving as a controllable rotor to halt or guide the movement.
Diaphragm check valve
A flexible rubber diaphragm is used in a diaphragm check valve to create a valve that is normally closed. In order for the check valve to open and allow flow, the pressure on the upstream side must be higher than the pressure on the downstream side by a specific amount called the pressure differential. When the positive pressure ceases, the diaphragm automatically returns to its original closed position. This particular type of valve is commonly employed in respirators, such as face masks, that have an exhalation valve.
Swing check valve
A swing check valve, also known as a tilting disc check valve, is a type of check valve that uses a disc to control the flow. The disc swings on a hinge or trunnion, either blocking the flow to prevent reverse flow or allowing the flow to move forward. The opening of the seat can be perpendicular to the centerline between the two ports or at an angle. While swing check valves come in different sizes, larger ones are often swing check valves. One common problem associated with swing check valves is called water hammer. This occurs when the swing check valve closes and the flow suddenly stops, creating a surge of pressure that generates high-speed shock waves. These shock waves put stress on the piping and valves, causing vibrations in the system. If not detected, water hammer can lead to the rupture of pumps, valves, and pipes in the system.
The flush toilet's flapper valve is an instance of this kind of valve. The pressure in the tank keeps it closed, but it can be manually lifted to open. It stays open until the tank empties and gravity causes the flapper to fall back down. Another type of valve like this is the clapper valve, which is used in firefighting and fire safety systems. It has a hinged gate that only opens in one direction. The clapper valve usually has a spring that keeps the gate closed when there is no pressure pushing it forward. Another example is the backwater valve, which is used in sanitary drainage systems to prevent flooding from sewage water flowing back. This risk is most common in drainage systems connected to combined sewerage systems and rainwater drainage systems. It can happen during heavy rain, thawing, or floods.
Large butterfly check valve for a water pump
The butterfly check valve is a modified version of the swing check valve. It consists of two flaps that are hinged and function as check valves to avoid reverse flow. It is important to note that the butterfly check valve should not be mistaken for the butterfly valve, which is utilized for regulating flow and lacks the ability to allow flow in only one direction.
Stop-check valve
A stop-check valve is a type of check valve that has a control feature to halt the flow, regardless of the direction or pressure of the flow. Apart from closing automatically when there is backflow or insufficient forward pressure, like a regular check valve, it can also be intentionally closed using an external mechanism. This allows it to prevent any flow, regardless of the forward pressure.
Lift-check valve
A lift-check valve is a type of check valve where the disc, also known as a lift, can be raised from its position by the increased pressure of the fluid entering from the inlet or upstream. This enables the flow to pass through to the outlet or downstream side. To ensure proper functioning, a guide keeps the disc moving in a vertical direction. Once the pressure equalizes or the downstream pressure becomes higher, gravity or the increased pressure will cause the disc to descend onto its seat, effectively closing the valve and preventing reverse flow.
In-line check valve
A check valve that operates in a straight line is known as an in-line check valve. It functions similarly to a lift check valve, but with the addition of a spring that will raise when there is pressure on the side of the valve facing upstream. The amount of pressure required to surpass the spring's resistance is referred to as the "cracking pressure". If the pressure passing through the valve drops below the cracking pressure, the spring will shut the valve to prevent any reverse flow.
Duckbill valve
A duckbill valve functions as a one-way valve where the movement of fluid occurs through a flexible tube that extends into the area where the flow is directed. When there is pressure from the opposite direction, this tube collapses, preventing any further flow.
Reed valve
A reed valve is a type of valve that is made up of a flexible flat sheet. This sheet seals a plate with a small opening. The pressure needed to open the valve is very low, and the part that moves is lightweight, allowing for quick operation. The resistance to the flow of air or gas is moderate, and the seal becomes better when there is pressure from the opposite direction. Reed valves are commonly used in two-stroke internal combustion engines to control the intake of air into the crankcase. They are also used in air compressors to control the intake and exhaust of air in the cylinder(s). While reed valves are typically used for gases rather than liquids, the Autotrol brand of water treatment control valves uses a set of reed valves to take advantage of their sealing properties. These valves selectively open some of the reeds to create a pathway for water flow.
Flow check
A flow check is a type of valve used in heating and cooling systems to prevent unwanted flow caused by gravity. It is a simple valve made of heavy metal that is designed to allow for low resistance flow, long-lasting performance, and the ability to clean itself from any particles found in the system. Unlike other valves, the flow check is not conical in shape and instead has a circular recess that fits over a narrow ridge at the edge of an opening. This design allows for a small amount of reverse leakage, so a perfect seal is not necessary. Additionally, the flow check has a screw that can be used to keep the valve open, which is useful for filling and purging air from the system.
You can connect several check valves in a row. For instance, a dual check valve is commonly employed as a safeguard against backflow, preventing potentially polluted water from flowing back into the public water supply lines. Additionally, there are dual ball check valves that have two sets of ball and seat arranged consecutively within a single body, ensuring a secure seal to block reverse flow. Other types of check valves include piston check valves, wafer check valves, and ball-and-cone check valves.
Industrial processes
Check valves are commonly utilized in various fluid systems, including those found in chemical and power plants, as well as in numerous other industrial operations.
In the nuclear sector, feed water control systems, dump lines, make-up water systems, miscellaneous process systems, N2 systems, and monitoring and sampling systems are among the typical applications. In the realm of aircraft and aerospace, check valves are employed in situations involving intense vibration, extreme temperature fluctuations, and corrosive fluids. For instance, they are crucial for controlling propulsion propellants in spacecraft and launch vehicles, particularly for reaction control systems (RCS) and Attitude Control Systems (ACS), as well as in aircraft hydraulic systems.
Check valves are frequently employed in situations where various gases are combined into a single gas flow. Each gas stream is equipped with a check valve to prevent the gases from mixing at the source. For instance, if a fuel and an oxidizer need to be blended, check valves will typically be installed on both the fuel and oxidizer sources. This precaution ensures that the initial gas cylinders maintain their purity and do not become flammable.
Domestic use
To ensure that contaminated water does not flow back into the clean drinking water supply, a backflow preventer, known as a check valve, is installed when connecting a sanitary water source to an unsanitary system like sprinklers, dishwashers, or washing machines.
Certain types of irrigation sprinklers and drip irrigation emitters incorporate small valves that prevent the drainage of water when the system is turned off.
Valves employed in household heating systems to hinder vertical convection, particularly when combined with solar thermal installations, are also referred to as gravity brakes.
Rainwater harvesting systems that are connected to the main water supply of a utility provider may necessitate the installation of one or more valves to safeguard against the contamination of the primary supply by rainwater.
Hydraulic jacks utilize ball valves to generate pressure on the lifting side of the jack.
Inflatable objects, such as toys, mattresses, and boats, often utilize check valves. This enables the objects to be inflated without the need for continuous or uninterrupted air pressure.
How are Check Valves Used?
Ever since the self-sealing valve was created in the early 1900s, it has been the solution to backflow issues in various industries. Any industry that uses pipes to transport goods has a check valve incorporated into their system.
Check valves are beneficial tools that save money by preventing waste and safeguarding equipment. It is crucial to prevent the loss of fluids during their journey through a piping system. Check valves efficiently halt the flow of liquids when there is a drop in pressure or a decrease in flow, effectively blocking any reverse flow and keeping the fluid contained.
Where Check Valve Uses?
Pharmaceutical/Sanitary Check Valve
In the pharmaceutical sector, the utilization of check valves is necessary to facilitate the fluid movement. These valves play a crucial role in maintaining optimal pressure within the fluid flow, thereby ensuring top-notch product quality, operational efficiency, and smooth production. However, it is imperative to exclusively employ sanitary check valves for this purpose. These valves are designed to be easily cleaned, eliminating the need for disassembling, and they possess the ability to silently close while providing a secure seal.
Aircraft Hydraulic Systems/Aircraft Hydraulic Systems Check Valves
Orifice examination valves are employed in the hydraulic system of the actuator mechanism for landing gear. When the gear is elevated, liquid is directed to elevate the gear. Conversely, when the gear is lowered, the check valve prevents the gear from descending by regulating the outflow from the actuator. In addition to the landing gear, check valves are utilized in various hydraulic systems, fuel systems, and pneumatic systems of aircraft.
Irrigation Systems
Check valves are positioned close to the origin of an irrigation system to hinder the reverse flow, or siphonage, of water used for irrigation back towards the source.
Fuel Pump Check Valve
Check valves can be observed in automobiles manufactured prior to the advent of electronic injection systems. In older car fuel pumps, a check valve is positioned both at the inlet and outlet of the pump. These valves are intended to ensure the proper flow direction of fuel. In the event of a malfunctioning check valve, the fuel pressure decreases.
Water Supply Check Valves
In a household, water should only flow from the main pipe to a fixture or from a drain to the sewage system. To avoid mixing or reverse flow, check valves are installed in homes. These valves come in different types such as ball and swing check valves. A diagram of a residential hot water system displays the placement of check valves.
Tempering Valve Diagram/Heating Boiler
Heating boilers are equipped with check valves to halt the circulation of hot water when the thermostat does not require heat. These valves effectively prevent water from flowing back into the boiler, thereby averting the accumulation of excessive pressure. Within a household heating boiler, a check valve is employed to ensure that boiler water does not mix with the domestic supply, safeguarding it against being utilized for drinking, bathing, or cooking purposes.
Heating System Boiler Check Valve
Check valves for liquid fuel are specifically engineered to function with various fuel types such as jet fuels, hydraulic oil, synthetic oil, and air. Their purpose is to maintain consistent performance throughout the entire range of valve opening, from the initial crack to full flow. To achieve this, an inverted spool is utilized, which incorporates a pressure sensor for equilibrium and steadiness, while also maintaining a specific pressure difference within the valve. This comprehensive design ensures that the valve opens evenly and smoothly.
How Various Types of Check Valves Work?
Swing/Swing Check Valve Design
Swing check valves have an unguided disc that moves into a fully open position when the pressure from the flow is applied. They come in several sizes and designs to fit different applications.
Lift
Lift check valves have a guided piston that lifts when the flow enters the check valve. The seat has a barrel design and is screwed on and sealed. The opening to the check valve is the same as the same size as the inlet and outlet.
Tilting
The design of tilting check valves is to overcome some of the problems of swing check valves, which have been the most common type. They are capable of remaining open when the flow has a low velocity and close quickly when the flow stops. They perform well in applications with high velocity.
Folding Disk
The folding disc check valve is a split disc design with a wafer body pattern that has a soft seat. The discs are secured by a pivot rod and open with the pressure of the flow. Springs on the discs help close the valve.
Vertical Check Valves
Vertical check valves are also known as spring check valves since a spring is used to keep the disc against the seat. The valve is held shut by the spring until a sufficient amount of pressure is applied to push the spring back and open the valve. Pressure keeps the valve open and the spring compressed. Once pressure drops, the spring forces the disc into the seat to shut off the flow. Vertical or spring check valves provide excellent backflow protection and are extremely reliable.
Advantages and Disadvantages of Check Valves
Check valves offer a significant advantage as they can function autonomously, requiring no supervision or regulation. Their fundamental structure enables them to be effortlessly placed within a pipe's current and effectively regulate the flow without any external control. Despite their numerous advantages, check valves, like any other mechanical device, do possess certain limitations.
Benefits of Check Valves
Stop reverse flow
Capable of withstanding high and low pressure situations
Serve as a secondary and safety mechanism
Suitable for both horizontal and vertical use
Automatically activated
Quick response time.
Safeguard pumps and compressors against damage caused by reverse flow
Minimize downtime and production loss
Prevent water hammering
Decrease unexpected valve breakdown
Decrease maintenance expenses
Limited number of mobile components
Compact size
Able to handle fluctuating flow conditions
Operate without the need for power
Check Valve for Horizontal Applications
Disadvantages of Check Valves
Do not operate in pulsating systems
Closing element can slam closed causing damage and wear
Operate in a completely enclosed system
Impossible to check if they are open or closed
Internal parts cannot be checked
Disks can get stuck in the open position.
Noise from slamming discs
Oversized Check Valves
Some check valve systems experience chattering due to the repeated opening and closing of the valve. This occurs when the check valve is too large for the application. When installing a check valve, it is important to choose the appropriate size. The disc should remain stable when open and create a tight seal when closed, preventing the valve from opening and closing repeatedly, fluttering, or failing.
Proper Installation
Improper installation and assembly of a check valve can lead to future issues. The first step is to select the correct check valve for the specific application. Factors such as flow capacity, positioning, and orientation are crucial. Placing a check valve too close to a pump can cause turbulence and potential damage to the valve. To prevent turbulence and the disc hitting the seat, check valves should be mounted several pipe diameters upstream from circulators, elbows, tees, and strainers.
Summary
Check valves serve as a means of regulating the movement of gases or liquids.
Check valves are economical tools that prevent wastage and safeguard machinery.
The characteristics of check valves differ based on factors such as flow rate, media density and temperature, pipe size, pressure, and flow velocity, as depicted in the provided diagram.
A standard check valve comprises four distinct components: body, seat, disc, and cover.
There is a wide range of check valve options available to suit various purposes.
Cast Steel CF8M 12” 150LB RF Flange Dual Plate Check Valve
Nominal Diameter: 12”(DN200)
Bore: Full Bore
Nominal Pressure: 150LB
Material: CF8M
Operation:N/A
Design Standard: API594/API602/API6DTest/Inspection: API598
End Connection: Lug
Lug standard: ASME/ANSI B16.5
Top Flange: N/A
Invest in the Cast Steel CF8M 10" 150LB RF Flange Dual Plate Check Valve and experience unmatched performance and peace of mind. Its professional design and impeccable features make it an ideal choice for various industrial applications.
Doubel Plate Check Valve
Double plate, spring loaded design to protect gas or liquid
piping system
Industry standards:
ASME B16.1, B16.5, B16.24, B16.34, B16.47, and B31.1
Main features:
The double plate check valve has a two spring loaded plate design to open to release medium and bounce back to prevent external leakage. This effective check valve can be installed from any location, providing a tight seal and guaranteed no pressure loss. Two valve plates are fixed to the valve body along a pivot axis, and two springs are installed on the butterfly plate above the sealing surface Under the push of the medium flow pressure, the spring is pressed, forcing the butterfly plate to open. When the medium is reversed, the spring forces the valve to close Such valves can be assembled in horizontal and vertical lines. The sealing surface of the disc and seat is made of alloy steel or hard alloy. With high temperature resistance, corrosion resistance, wear resistance, long service life characteristics. The valve adopts the overall structure, simple and compact, small impact force when closing, small water hammer pressure, high reliability. The valve body adopts no stop ring and no dew point structure, and the shell sealing performance is more reliable.
Application:
Modulating service
Airport refueling
Hydrocarbon processing
Chemical/petrochemical processing
Purified gas
Steam and vacuum services
Power and utilities
Refrigeration
HVAC
Alumina refining
Ball check valve
A ball is pushed forward through a hole, clearing the way for flow. The movement of the ball compresses a spring. Flow in the opposite direction pushes a ball against the hole, preventing flow out of the hole. A spring expands to keep the ball in place. A ball check valve can be open to allow forward flow or closed to block reverse flow. It is a type of check valve where the closing part is a ball. Some ball check valves have a spring to help keep the ball closed. In designs without a spring, reverse flow is needed to move the ball towards the seat and create a seal. The inner surface of the main seats of ball check valves are tapered to guide the ball into the seat and create a secure seal when stopping reverse flow.
Ball check valves are frequently found in various devices such as mini pump dispensers, spray devices, air pumps, and refillable syringes. These valves are typically small, uncomplicated, and inexpensive. While the balls are usually made of metal, they can also be constructed from other materials, including highly durable or inert substances like sapphire. In applications involving high pressure, such as in liquid chromatography pumps, inlet and outlet ball check valves with ruby balls and sapphire seats are commonly used for their hardness and chemical resistance. Over time, these valves may wear out or develop cracks in the seat, necessitating replacement. To address this, the valves are designed to be replaceable and are often housed in a plastic body securely fitted within a metal fitting that can withstand high pressure.
A disassembled poppet check valve
There exist check valves that have a different shape for the disc, like a poppet activated by a spring, instead of a ball. It is important not to mistake ball check valves with ball valves, as they are distinct types of valves. Ball valves employ a rotating ball on a pin to regulate and control the flow, serving as a controllable rotor to halt or guide the movement.
Diaphragm check valve
A flexible rubber diaphragm is used in a diaphragm check valve to create a valve that is normally closed. In order for the check valve to open and allow flow, the pressure on the upstream side must be higher than the pressure on the downstream side by a specific amount called the pressure differential. When the positive pressure ceases, the diaphragm automatically returns to its original closed position. This particular type of valve is commonly employed in respirators, such as face masks, that have an exhalation valve.
Swing check valve
A swing check valve, also known as a tilting disc check valve, is a type of check valve that uses a disc to control the flow. The disc swings on a hinge or trunnion, either blocking the flow to prevent reverse flow or allowing the flow to move forward. The opening of the seat can be perpendicular to the centerline between the two ports or at an angle. While swing check valves come in different sizes, larger ones are often swing check valves. One common problem associated with swing check valves is called water hammer. This occurs when the swing check valve closes and the flow suddenly stops, creating a surge of pressure that generates high-speed shock waves. These shock waves put stress on the piping and valves, causing vibrations in the system. If not detected, water hammer can lead to the rupture of pumps, valves, and pipes in the system.
The flush toilet's flapper valve is an instance of this kind of valve. The pressure in the tank keeps it closed, but it can be manually lifted to open. It stays open until the tank empties and gravity causes the flapper to fall back down. Another type of valve like this is the clapper valve, which is used in firefighting and fire safety systems. It has a hinged gate that only opens in one direction. The clapper valve usually has a spring that keeps the gate closed when there is no pressure pushing it forward. Another example is the backwater valve, which is used in sanitary drainage systems to prevent flooding from sewage water flowing back. This risk is most common in drainage systems connected to combined sewerage systems and rainwater drainage systems. It can happen during heavy rain, thawing, or floods.
Large butterfly check valve for a water pump
The butterfly check valve is a modified version of the swing check valve. It consists of two flaps that are hinged and function as check valves to avoid reverse flow. It is important to note that the butterfly check valve should not be mistaken for the butterfly valve, which is utilized for regulating flow and lacks the ability to allow flow in only one direction.
Stop-check valve
A stop-check valve is a type of check valve that has a control feature to halt the flow, regardless of the direction or pressure of the flow. Apart from closing automatically when there is backflow or insufficient forward pressure, like a regular check valve, it can also be intentionally closed using an external mechanism. This allows it to prevent any flow, regardless of the forward pressure.
Lift-check valve
A lift-check valve is a type of check valve where the disc, also known as a lift, can be raised from its position by the increased pressure of the fluid entering from the inlet or upstream. This enables the flow to pass through to the outlet or downstream side. To ensure proper functioning, a guide keeps the disc moving in a vertical direction. Once the pressure equalizes or the downstream pressure becomes higher, gravity or the increased pressure will cause the disc to descend onto its seat, effectively closing the valve and preventing reverse flow.
In-line check valve
A check valve that operates in a straight line is known as an in-line check valve. It functions similarly to a lift check valve, but with the addition of a spring that will raise when there is pressure on the side of the valve facing upstream. The amount of pressure required to surpass the spring's resistance is referred to as the "cracking pressure". If the pressure passing through the valve drops below the cracking pressure, the spring will shut the valve to prevent any reverse flow.
Duckbill valve
A duckbill valve functions as a one-way valve where the movement of fluid occurs through a flexible tube that extends into the area where the flow is directed. When there is pressure from the opposite direction, this tube collapses, preventing any further flow.
Reed valve
A reed valve is a type of valve that is made up of a flexible flat sheet. This sheet seals a plate with a small opening. The pressure needed to open the valve is very low, and the part that moves is lightweight, allowing for quick operation. The resistance to the flow of air or gas is moderate, and the seal becomes better when there is pressure from the opposite direction. Reed valves are commonly used in two-stroke internal combustion engines to control the intake of air into the crankcase. They are also used in air compressors to control the intake and exhaust of air in the cylinder(s). While reed valves are typically used for gases rather than liquids, the Autotrol brand of water treatment control valves uses a set of reed valves to take advantage of their sealing properties. These valves selectively open some of the reeds to create a pathway for water flow.
Flow check
A flow check is a type of valve used in heating and cooling systems to prevent unwanted flow caused by gravity. It is a simple valve made of heavy metal that is designed to allow for low resistance flow, long-lasting performance, and the ability to clean itself from any particles found in the system. Unlike other valves, the flow check is not conical in shape and instead has a circular recess that fits over a narrow ridge at the edge of an opening. This design allows for a small amount of reverse leakage, so a perfect seal is not necessary. Additionally, the flow check has a screw that can be used to keep the valve open, which is useful for filling and purging air from the system.
You can connect several check valves in a row. For instance, a dual check valve is commonly employed as a safeguard against backflow, preventing potentially polluted water from flowing back into the public water supply lines. Additionally, there are dual ball check valves that have two sets of ball and seat arranged consecutively within a single body, ensuring a secure seal to block reverse flow. Other types of check valves include piston check valves, wafer check valves, and ball-and-cone check valves.
Industrial processes
Check valves are commonly utilized in various fluid systems, including those found in chemical and power plants, as well as in numerous other industrial operations.
In the nuclear sector, feed water control systems, dump lines, make-up water systems, miscellaneous process systems, N2 systems, and monitoring and sampling systems are among the typical applications. In the realm of aircraft and aerospace, check valves are employed in situations involving intense vibration, extreme temperature fluctuations, and corrosive fluids. For instance, they are crucial for controlling propulsion propellants in spacecraft and launch vehicles, particularly for reaction control systems (RCS) and Attitude Control Systems (ACS), as well as in aircraft hydraulic systems.
Check valves are frequently employed in situations where various gases are combined into a single gas flow. Each gas stream is equipped with a check valve to prevent the gases from mixing at the source. For instance, if a fuel and an oxidizer need to be blended, check valves will typically be installed on both the fuel and oxidizer sources. This precaution ensures that the initial gas cylinders maintain their purity and do not become flammable.
Domestic use
To ensure that contaminated water does not flow back into the clean drinking water supply, a backflow preventer, known as a check valve, is installed when connecting a sanitary water source to an unsanitary system like sprinklers, dishwashers, or washing machines.
Certain types of irrigation sprinklers and drip irrigation emitters incorporate small valves that prevent the drainage of water when the system is turned off.
Valves employed in household heating systems to hinder vertical convection, particularly when combined with solar thermal installations, are also referred to as gravity brakes.
Rainwater harvesting systems that are connected to the main water supply of a utility provider may necessitate the installation of one or more valves to safeguard against the contamination of the primary supply by rainwater.
Hydraulic jacks utilize ball valves to generate pressure on the lifting side of the jack.
Inflatable objects, such as toys, mattresses, and boats, often utilize check valves. This enables the objects to be inflated without the need for continuous or uninterrupted air pressure.
How are Check Valves Used?
Ever since the self-sealing valve was created in the early 1900s, it has been the solution to backflow issues in various industries. Any industry that uses pipes to transport goods has a check valve incorporated into their system.
Check valves are beneficial tools that save money by preventing waste and safeguarding equipment. It is crucial to prevent the loss of fluids during their journey through a piping system. Check valves efficiently halt the flow of liquids when there is a drop in pressure or a decrease in flow, effectively blocking any reverse flow and keeping the fluid contained.
Where Check Valve Uses?
Pharmaceutical/Sanitary Check Valve
In the pharmaceutical sector, the utilization of check valves is necessary to facilitate the fluid movement. These valves play a crucial role in maintaining optimal pressure within the fluid flow, thereby ensuring top-notch product quality, operational efficiency, and smooth production. However, it is imperative to exclusively employ sanitary check valves for this purpose. These valves are designed to be easily cleaned, eliminating the need for disassembling, and they possess the ability to silently close while providing a secure seal.
Aircraft Hydraulic Systems/Aircraft Hydraulic Systems Check Valves
Orifice examination valves are employed in the hydraulic system of the actuator mechanism for landing gear. When the gear is elevated, liquid is directed to elevate the gear. Conversely, when the gear is lowered, the check valve prevents the gear from descending by regulating the outflow from the actuator. In addition to the landing gear, check valves are utilized in various hydraulic systems, fuel systems, and pneumatic systems of aircraft.
Irrigation Systems
Check valves are positioned close to the origin of an irrigation system to hinder the reverse flow, or siphonage, of water used for irrigation back towards the source.
Fuel Pump Check Valve
Check valves can be observed in automobiles manufactured prior to the advent of electronic injection systems. In older car fuel pumps, a check valve is positioned both at the inlet and outlet of the pump. These valves are intended to ensure the proper flow direction of fuel. In the event of a malfunctioning check valve, the fuel pressure decreases.
Water Supply Check Valves
In a household, water should only flow from the main pipe to a fixture or from a drain to the sewage system. To avoid mixing or reverse flow, check valves are installed in homes. These valves come in different types such as ball and swing check valves. A diagram of a residential hot water system displays the placement of check valves.
Tempering Valve Diagram/Heating Boiler
Heating boilers are equipped with check valves to halt the circulation of hot water when the thermostat does not require heat. These valves effectively prevent water from flowing back into the boiler, thereby averting the accumulation of excessive pressure. Within a household heating boiler, a check valve is employed to ensure that boiler water does not mix with the domestic supply, safeguarding it against being utilized for drinking, bathing, or cooking purposes.
Heating System Boiler Check Valve
Check valves for liquid fuel are specifically engineered to function with various fuel types such as jet fuels, hydraulic oil, synthetic oil, and air. Their purpose is to maintain consistent performance throughout the entire range of valve opening, from the initial crack to full flow. To achieve this, an inverted spool is utilized, which incorporates a pressure sensor for equilibrium and steadiness, while also maintaining a specific pressure difference within the valve. This comprehensive design ensures that the valve opens evenly and smoothly.
How Various Types of Check Valves Work?
Swing/Swing Check Valve Design
Swing check valves have an unguided disc that moves into a fully open position when the pressure from the flow is applied. They come in several sizes and designs to fit different applications.
Lift
Lift check valves have a guided piston that lifts when the flow enters the check valve. The seat has a barrel design and is screwed on and sealed. The opening to the check valve is the same as the same size as the inlet and outlet.
Tilting
The design of tilting check valves is to overcome some of the problems of swing check valves, which have been the most common type. They are capable of remaining open when the flow has a low velocity and close quickly when the flow stops. They perform well in applications with high velocity.
Folding Disk
The folding disc check valve is a split disc design with a wafer body pattern that has a soft seat. The discs are secured by a pivot rod and open with the pressure of the flow. Springs on the discs help close the valve.
Vertical Check Valves
Vertical check valves are also known as spring check valves since a spring is used to keep the disc against the seat. The valve is held shut by the spring until a sufficient amount of pressure is applied to push the spring back and open the valve. Pressure keeps the valve open and the spring compressed. Once pressure drops, the spring forces the disc into the seat to shut off the flow. Vertical or spring check valves provide excellent backflow protection and are extremely reliable.
Advantages and Disadvantages of Check Valves
Check valves offer a significant advantage as they can function autonomously, requiring no supervision or regulation. Their fundamental structure enables them to be effortlessly placed within a pipe's current and effectively regulate the flow without any external control. Despite their numerous advantages, check valves, like any other mechanical device, do possess certain limitations.
Benefits of Check Valves
Stop reverse flow
Capable of withstanding high and low pressure situations
Serve as a secondary and safety mechanism
Suitable for both horizontal and vertical use
Automatically activated
Quick response time.
Safeguard pumps and compressors against damage caused by reverse flow
Minimize downtime and production loss
Prevent water hammering
Decrease unexpected valve breakdown
Decrease maintenance expenses
Limited number of mobile components
Compact size
Able to handle fluctuating flow conditions
Operate without the need for power
Check Valve for Horizontal Applications
Disadvantages of Check Valves
Do not operate in pulsating systems
Closing element can slam closed causing damage and wear
Operate in a completely enclosed system
Impossible to check if they are open or closed
Internal parts cannot be checked
Disks can get stuck in the open position.
Noise from slamming discs
Oversized Check Valves
Some check valve systems experience chattering due to the repeated opening and closing of the valve. This occurs when the check valve is too large for the application. When installing a check valve, it is important to choose the appropriate size. The disc should remain stable when open and create a tight seal when closed, preventing the valve from opening and closing repeatedly, fluttering, or failing.
Proper Installation
Improper installation and assembly of a check valve can lead to future issues. The first step is to select the correct check valve for the specific application. Factors such as flow capacity, positioning, and orientation are crucial. Placing a check valve too close to a pump can cause turbulence and potential damage to the valve. To prevent turbulence and the disc hitting the seat, check valves should be mounted several pipe diameters upstream from circulators, elbows, tees, and strainers.
Summary
Check valves serve as a means of regulating the movement of gases or liquids.
Check valves are economical tools that prevent wastage and safeguard machinery.
The characteristics of check valves differ based on factors such as flow rate, media density and temperature, pipe size, pressure, and flow velocity, as depicted in the provided diagram.
A standard check valve comprises four distinct components: body, seat, disc, and cover.
There is a wide range of check valve options available to suit various purposes.
