Check valves in Dubai UAE

In Marine Land company ,When the pressure in the piping causes the flow to be reversed, the check valves UAE protect the pumps and other equipment from damage from the return flow. They are used in flow control applications such as line separation, priming pumps, injection, head pressure maintenance and many more.

A check valve, non-return valve, reflux valve, retention valve, foot valve, or one-way valve is a valve that normally allows fluid (liquid or gas) to pass through only one direction.

Inspection valves are two-port valves, meaning they have two valves in the body, one for liquid entry and the other for liquid exit. Different types of check valves are used in different applications. Check taps are often part of the common household items. Although they are available in a wide range of sizes and costs, Czech taps are usually very small, simple, and inexpensive. Check valves work automatically and most of them are not controlled by one person or any external control. Accordingly, most of them have no valve handles or stems. Body (outer shells) Most Czech valves are made of plastic or metal.

An important concept in inspection valves is the crack pressure, which is the minimum upstream differential pressure between the inlet and outlet where the valve operates. The check valve is usually designed for a specific cracking pressure and can therefore be determined.

 

Technical expressions

Cracking pressure - refers to the minimum pressure difference between the inlet and outlet of the valve at which the first sign of flow occurs (constant flow of bubbles). Cracking pressure is also known as pressure (pressure) or opening pressure.

Re-sealing pressure - refers to the pressure difference between the inlet and outlet of the valve during the closing process of the return valve in which the amount of leakage is not visible. Re-sealing pressure is also known as sealing pressure, settling pressure (pressure), or closing pressure.

Back pressure - the pressure at the outlet of the joints greater than the inlet pressure or upstream point.

 

Types of check valves

 

• Ball check valve

A ball check valve is a check valve in which the closing member, the moving part to block the flow, is a ball. In some ball check valves, the ball uses a spring to help keep it closed. For designs without springs, reverse flow is required to move the ball toward the seat and create a seal. The inner surface of the main seats of the ball check valves is more or less conical to guide the ball into the seat and to create a positive seal when the reverse flow stops.

Ball check valves are often very small, simple, and inexpensive. They are commonly used in small liquid or gel pumping spigots, sprayers, some rubber bulbs for air pumping, etc., hand-held air pumps and some other pumps, and rechargeable dispensing syringes. Although balls are often made of metal, they can also be made of other materials. In some specialized cases of very durable or ineffective materials such as sapphire. HPLC high-pressure pumps and similar applications typically use small inlet and outlet ball check valves with sapphire balls and chairs made of sapphire or both ruby ​​ball and seat for hardness and chemical resistance. After prolonged use, such check valves may eventually wear out or the seat may crack and need to be replaced. Thus, such valves are made to be interchangeable, sometimes housed in a small plastic body that fits snugly into a metal fitting that can withstand high pressure and is screwed to the pump head.

There are similar check valves where the disc is not a ball, but a different shape, like a hole powered by a spring. Ball check valves should not be confused with ball valves, which are a different type of valve in which the ball acts as a controllable rotor to stop or direct current.

 

• Diaphragm check valve

A diaphragm check valve uses a bending rubber diaphragm that is positioned to create a normally closed valve. The pressure upstream must be greater than the pressure downstream, known as the pressure differential, to open the check valve and allow flow. When the positive pressure stops, the diaphragm automatically bends to its original closed position.

 

• Swing check valve

A swing check valve, or tilting disc check valve, is a valve in which the disc, the moving part that blocks the flow, rotates on an open hinge or strap, or rotates on a seat to block the reverse flow, or from a seat. It comes out to create a forward flow. The cross-section of the seat opening may be perpendicular to the centerline between two ports or at an angle. Although swing check valves can be of different sizes, large check valves are usually swing check valves. A common problem caused by the rotation of the valves is known as water hammering. This can happen when the oscillation check closes and the flow suddenly stops, increasing the pressure, resulting in high-velocity shock waves acting against the pipes and valves, putting a lot of pressure on metals and vibrations. Enters the system. Unidentified water hammers can rupture pumps, valves, and pipes inside the system.

 

• Flapper valve

The flapper valve in the toilet flash mechanism is an example of this type of valve. The pressure of the tank that holds it closed is relieved by lifting the flapper manually. It is then left open until the tank is emptied and the flapper is dropped by gravity. Another type of mechanism is the valve, which is used in applications such as fire and fire safety systems. A hinged gate remains open only in the entrance direction. The clapper valve often has a spring that keeps the gate closed if there is no forward pressure. Another example is the back faucet (for sanitary drainage system) which protects against flooding caused by the return flow of sewage water. Such a risk often occurs in sanitary drainage systems connected to combined sewage systems and in rainwater drainage systems. Heavy rain, melting or flooding may occur.

 

• Stop-check valve

The stop-check valve is a check valve with flow override control to stop the flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be closed intentionally by an external mechanism, thus preventing any flow regardless of forwarding pressure.

 

• Lift-check valve

The lift-check valve is a check valve in which the disc, sometimes called the lift, can lift the inlet or upstream fluid from its seat at a higher pressure to allow the flow to flow out or downstream. A guide keeps the disk moving on a vertical line, so the valve can be positioned correctly later. When the pressure is no longer high, gravity or lower downstream pressure causes the disc to lower on its seat and close the valve to stop the reverse flow.

 

• In-line check valve

The in-line check valve is a check valve similar to the lift check valve. However, this valve generally has a spring that "lifts" when there is pressure upstream of the valve. The pressure required upstream of the valve to overcome the spring tension is called the "crack pressure". When the pressure passing through the valve reaches below the crack pressure, the spring closes the valve to prevent backflow in the process.

 

• Duckbill valve

A duckbill valve is a check valve in which the flow is expelled through a soft tube downstream. The return pressure of this pipe collapses and cuts off the flow.

 

• A non-return pneumatic valve.

 

• Reed valve

A reed valve is a check valve formed by a flexible smooth sheet that seals the orifice plate. The crack pressure is very low, the moving part has a low mass that allows fast operation, the flow resistance is medium and the sealing is improved by return pressure. They are commonly found in two-stroke internal combustion engines as air intake valves for crankshaft volume and in air compressors as inlet and exhaust valves for cylinders. Although reed valves are commonly used for gases instead of liquids, the Autotrol brand of water treatment control valves is designed as a set of reed valves that take advantage of the sealing feature and selectively open some of the needles to create a flow path.

 

• Flow Check valve

Flow Check is a check valve used in hydraulic heating and cooling systems to prevent unwanted inertial gravitational flow. Flow Check A heavy metal cap is a simple gravitational package designed to withstand low currents, decades of continuous service, and to clean fine particles typically in hydraulic systems from sealing surfaces. For self-cleaning, the cap is usually not tapered. A circular depression in the weight that rests on an identical narrow protrusion at the edge of the orifice is a common design. The program inherently tolerates a moderate reverse leakage rate, complete sealing is not required. The flow check has an operating screw that allows the valve to keep the valve open, as opposed to the stop-check valve, as an aid to filling the system and venting the system.

Several check valves can be connected in series. For example, a double check valve is often used as a backflow preventer to prevent potentially contaminated water from being siphoned into municipal water supply lines. There are also double ball check valves in which there are two consecutive ball/seat combinations in one body to ensure positive leakage when blocking the reverse flow. And piston check valves, wafer check valves, and ball-and-cone check valves.

 

Applications

 

• Pumps

The check valves in this steam locomotive are located under a small cover between the chimney and the main dome.

Check valves are often used in some types of pumps. Piston and diaphragm pumps, such as metering pumps and chromatographic pumps, typically use inlet and outlet ball check valves. These valves often look like small cylinders connected to the pump head at the inlet and outlet lines. Many pump-like mechanisms use check valves, such as ball check valves, to move the volume of fluid around. Feed pumps or injectors that deliver water to boilers have check valves to prevent backflow.

Check valves are also used in pumps that supply water to water slides. Water flows to the slide through a pipe that acts as a support tower for the slide stairs. When the facility closes with a slide for the night, the check valve stops the flow of water through the pipe. When the facility reopens for the next day, the valve opens and the flow resumes, preparing the slide for reuse.

 

• Industrial processes

Check valves are used in many fluid systems such as chemical systems and power plants and many other industrial processes.

Typical applications in the nuclear industry include feed water control systems, drainage lines, preparation water, miscellaneous process systems, N2 systems, and monitoring and sampling systems. In aircraft and aerospace, check valves are used in places where there is a high vibration, high temperature, and corrosive fluids. For example, propulsion control of spacecraft propulsion and launch for reaction control systems (RCS), attitude control systems (ACS), and aircraft hydraulic systems.

Check valves are often used when multiple gases are mixed in one gas stream. To prevent the mixing of gases in the main source, a check valve is installed on each of the gas streams separately. For example, if fuel and oxidizer are to be mixed, check valves are commonly used at both the fuel source and the oxidizer source to ensure that the main gas cylinders remain clean and therefore non-flammable.

In 2010, NASA's Jet Propulsion Laboratory slightly modified a simple check valve design to store liquid samples of life on Mars in separate spacecraft without fear of cross-contamination.

 

• Domestic use

When a sanitary drinking water source is piped into an unsanitary system, for example, a lawn sprinkler, dishwasher, or washing machine, a check valve called a backflow preventer is used to prevent contaminated water from re-entering the domestic water supply. Be.

Some types of irrigation sprinklers and drip irrigation sprinklers have small check valves that prevent the lines from draining when the system is turned off.

Check valves used in home heating systems to prevent vertical convection, especially in combination with solar thermal installations, are also called gravity brakes.

Rainwater collection systems that are piped to the main source of water supply may require the installation of one or more check valves to prevent primary rainwater contamination.

Hydraulic jacks use ball check valves to apply pressure to the lift side of the jack.

Check valves are commonly used in inflatable items such as toys, mattresses, and boats. This allows the body to inflate without constant air pressure or interruption.