TONY Introduction And Application Of Some Types Of Check Valves
Check valve, check valve, return valve, holding valve, foot valve or check valve usually allow fluid (liquid or gas) to flow in one direction only.
Check valves are double port valves, which means they have two openings in the valve body, one for fluid entry and one for fluid exit. There are various types of check valves for various applications. Check valves are usually part of ordinary household items. Although check valves come in a variety of sizes and costs, they are usually very small, simple, and inexpensive. The check valve works automatically, most of which are not controlled by people or any external control device; Therefore, most valves do not have any valve handles or stems. The body (shell) of most check valves is made of plastic or metal.
An important concept in check valves is the rupture pressure, which is the minimum upstream differential pressure between the inlet and outlet when the valve is operating. Generally, check valves are designed for a specific burst pressure, so they can be specified for a specific pressure.
Check valve type
Go forward through a hole and push a ball that blocks the far side of the hole to let the water flow. The motion of the ball compresses the spring.
Reverse flow pushes the ball onto the hole to prevent outward flow through the hole. The spring expands to help hold the ball in place.
The ball valve in the open position allows forward flow, while the ball valve in the closed position prevents reverse flow
A ball check valve is a check valve in which the closing member is a sphere and the movable part is used to stop the flow of fluid. In some ball check valves, the ball is spring loaded to help keep it closed. For designs without springs, reverse flow is required to move the ball toward the seat and form a seal. The inner surface of the main seat of the ball check valve is more or less tapered to guide the ball into the seat and form a positive seal when reverse flow stops.
There are similar check valves, in which the disc is not spherical, but other shapes, such as a spring actuated poppet. Ball check valve shall not be confused with ball valve. Ball valve is a different type of valve, in which the ball acts as a controllable rotor to stop or guide the fluid.
Diaphragm check valves use a flexible rubber diaphragm to form a normally closed valve. The pressure on the upstream side must be a certain amount greater than that on the downstream side, which is called differential pressure, so that the check valve can open to allow flow. Once the positive pressure stops, the diaphragm automatically bends back to its original closed position. This type is used for respirators (masks) with expiratory valves.
Swing check valve opening and closing
A swing check valve or tilting disc check valve is a check valve in which the disc (a movable part that prevents fluid flow) swings on a hinge or trunnion, or on the seat to prevent reverse flow, or leaves the seat to allow forward flow. The cross section of the valve seat opening can be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can be of various sizes, large check valves are usually swing check valves. A common problem caused by swing check valves is called water hammer. When the swing check valve is closed and the flow stops suddenly, this will happen, resulting in a surge of pressure, resulting in a high-speed shock wave acting on the pipe and valve, exerting greater stress on the metal, and causing the system to vibrate. Without detection, water hammer will break the pumps, valves and pipes in the system.
Stop check valve is a check valve with override control, which can stop the flow regardless of the flow direction or pressure. In addition to closing in response to insufficient backflow or forward pressure (normal check valve behavior), it can also be intentionally closed by an external mechanism to prevent any flow regardless of forward pressure.
Application
Industrial process
Check valves are used in many fluid systems, such as chemical plants and power plants, as well as many other industrial processes.
Typical applications in the nuclear industry are feedwater control systems, discharge lines, makeup water, other process systems, nitrogen systems, and monitoring and sampling systems. [14] In aircraft and aerospace, check valves are used in the presence of high vibration, high temperature limits and corrosive fluids. For example, propulsion propellant control of spacecraft and launch vehicles for reaction control systems (RCS) and attitude control systems (ACS), as well as aircraft hydraulic systems.
Check valves are also often used when multiple gases are mixed into a single stream of air. A check valve is installed on each individual gas flow to prevent gas mixing in the original source. For example, if fuel and oxidant are to be mixed, check valves are usually used on the fuel source and oxidant source to ensure that the original cylinder remains pure and therefore nonflammable.
Check valves are double port valves, which means they have two openings in the valve body, one for fluid entry and one for fluid exit. There are various types of check valves for various applications. Check valves are usually part of ordinary household items. Although check valves come in a variety of sizes and costs, they are usually very small, simple, and inexpensive. The check valve works automatically, most of which are not controlled by people or any external control device; Therefore, most valves do not have any valve handles or stems. The body (shell) of most check valves is made of plastic or metal.
An important concept in check valves is the rupture pressure, which is the minimum upstream differential pressure between the inlet and outlet when the valve is operating. Generally, check valves are designed for a specific burst pressure, so they can be specified for a specific pressure.
Check valve type
Go forward through a hole and push a ball that blocks the far side of the hole to let the water flow. The motion of the ball compresses the spring.
Reverse flow pushes the ball onto the hole to prevent outward flow through the hole. The spring expands to help hold the ball in place.
The ball valve in the open position allows forward flow, while the ball valve in the closed position prevents reverse flow
A ball check valve is a check valve in which the closing member is a sphere and the movable part is used to stop the flow of fluid. In some ball check valves, the ball is spring loaded to help keep it closed. For designs without springs, reverse flow is required to move the ball toward the seat and form a seal. The inner surface of the main seat of the ball check valve is more or less tapered to guide the ball into the seat and form a positive seal when reverse flow stops.
There are similar check valves, in which the disc is not spherical, but other shapes, such as a spring actuated poppet. Ball check valve shall not be confused with ball valve. Ball valve is a different type of valve, in which the ball acts as a controllable rotor to stop or guide the fluid.
Diaphragm check valves use a flexible rubber diaphragm to form a normally closed valve. The pressure on the upstream side must be a certain amount greater than that on the downstream side, which is called differential pressure, so that the check valve can open to allow flow. Once the positive pressure stops, the diaphragm automatically bends back to its original closed position. This type is used for respirators (masks) with expiratory valves.
Swing check valve opening and closing
A swing check valve or tilting disc check valve is a check valve in which the disc (a movable part that prevents fluid flow) swings on a hinge or trunnion, or on the seat to prevent reverse flow, or leaves the seat to allow forward flow. The cross section of the valve seat opening can be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can be of various sizes, large check valves are usually swing check valves. A common problem caused by swing check valves is called water hammer. When the swing check valve is closed and the flow stops suddenly, this will happen, resulting in a surge of pressure, resulting in a high-speed shock wave acting on the pipe and valve, exerting greater stress on the metal, and causing the system to vibrate. Without detection, water hammer will break the pumps, valves and pipes in the system.
Stop check valve is a check valve with override control, which can stop the flow regardless of the flow direction or pressure. In addition to closing in response to insufficient backflow or forward pressure (normal check valve behavior), it can also be intentionally closed by an external mechanism to prevent any flow regardless of forward pressure.
Application
Industrial process
Check valves are used in many fluid systems, such as chemical plants and power plants, as well as many other industrial processes.
Typical applications in the nuclear industry are feedwater control systems, discharge lines, makeup water, other process systems, nitrogen systems, and monitoring and sampling systems. [14] In aircraft and aerospace, check valves are used in the presence of high vibration, high temperature limits and corrosive fluids. For example, propulsion propellant control of spacecraft and launch vehicles for reaction control systems (RCS) and attitude control systems (ACS), as well as aircraft hydraulic systems.
Check valves are also often used when multiple gases are mixed into a single stream of air. A check valve is installed on each individual gas flow to prevent gas mixing in the original source. For example, if fuel and oxidant are to be mixed, check valves are usually used on the fuel source and oxidant source to ensure that the original cylinder remains pure and therefore nonflammable.
