These water valves are operated by.A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or ) by opening, closing, or partially obstructing various passageways. Valves are technically, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure. The word is derived from the Latin valva, the moving part of a door, in turn from volvere, to turn, roll.The simplest, and very ancient, valve is simply a freely hinged flap which drops to obstruct fluid (gas or liquid) flow in one direction, but is pushed open by flow in the opposite direction. This is called a, as it prevents or 'checks' the flow in one direction. Modern may regulate or downstream and operate on sophisticated systems.Valves have many uses, including controlling water for, industrial uses for controlling processes, residential uses such as on/off and pressure control to dish and clothes washers and taps in the home. Even aerosols have a tiny valve built in.

Valves are also used in the military and transport sectors. In and other near-atmospheric air flows, valves are instead called.

In compressed air systems, however, valves are used with the most common type being ball valves. Cross-sectional diagram of an open.1. Disc when valve is open6.

Handle or handwheel when valve is open7. Fluid flow when valve is open11. Position of disc if valve were shut12. Position of handle or handwheel if valve were shutThe main parts of the most usual type of valve are the body and the bonnet. These two parts form the casing that holds the fluid going through the valve.BodyThe valve's body is the outer casing of most or all of the valve that contains the internal parts or trim.

The bonnet is the part of the through which the (see below) passes and that forms a guide and seal for the stem. The bonnet typically screws into or is bolted to the valve body.Valve bodies are usually or., and are very common. Seawater applications, like desalination plants, often use duplex valves, as well as super duplex valves, due to their corrosion resistant properties, particularly against warm seawater. Valves are typically used in sulphuric acid plants, whilst valves are used in (HF Acid) plants.

Valves are often used in high temperature applications, such as nuclear plants, whilst valves are often used in hydrogen applications. Plastic bodies are used for relatively low pressures and temperatures., and are common plastics used for valve bodies. BonnetA bonnet acts as a cover on the valve body. It is commonly semi-permanently screwed into the valve body or bolted onto it. During of the valve, the internal parts are put into the body and then the bonnet is attached to hold everything together inside. To access internal parts of a valve, a user would take off the bonnet, usually for maintenance. Many valves do not have bonnets; for example, usually do not have bonnets.

Many ball valves do not have bonnets since the valve body is put together in a different style, such as being screwed together at the middle of the valve body.PortsPorts are passages that allow fluid to pass through the valve. Ports are obstructed by the valve member or disc to control flow. Valves most commonly have 2 ports, but may have as many as 20.

2 Way Angle Valve Vs 3 Way Angle Valve Installation

The valve is almost always connected at its ports to pipes or other components. Connection methods include, or.Handle or actuatorA is used to manually control a valve from outside the valve body. Automatically controlled valves often do not have handles, but some may have a handle (or something similar) anyway to manually override automatic control, such as a.

3 way valve working principle

An is a mechanism or device to automatically or remotely control a valve from outside the body. Some valves have neither handle nor actuator because they automatically control themselves from inside; for example, and may have neither.Disc. Valve discA disc or valve member is a movable obstruction inside the stationary body that adjustably restricts flow through the valve. Although traditionally disc-shaped, discs come in various shapes. Depending on the type of valve, a disc can move linearly inside a valve, or rotate on the stem (as in a ), or rotate on a or (as in a ). A ball is a round valve member with one or more paths between ports passing through it. By rotating the ball, flow can be directed between different ports.

Use spherical rotors with a cylindrical hole drilled as a fluid passage. Use cylindrical or conically tapered rotors called plugs. Other round shapes for rotors are possible as well in rotor valves, as long as the rotor can be turned inside the valve body. However, not all round or spherical discs are rotors; for example, a ball uses the ball to block reverse flow, but is not a rotor because operating the valve does not involve rotation of the ball.SeatThe seat is the interior surface of the body which contacts the disc to form a leak-tight seal. In discs that move linearly or swing on a hinge or, the disc comes into contact with the seat only when the valve is shut. In disks that rotate, the seat is always in contact with the disk, but the area of contact changes as the disc is turned.

The seat always remains stationary relative to the body.Seats are classified by whether they are cut directly into the body, or if they are made of a different material:. Hard seats are integral to the valve body. Nearly all hard seated metal valves have a small amount of.

Soft seats are fitted to the valve body and made of softer materials such as or various such as, or depending on the maximum. A closed soft seated valve is much less liable to leak when shut while hard seated valves are more durable. Gate, globe, and check valves are usually hard seated while butterfly, ball, plug, and diaphragm valves are usually soft seated.StemThe stem transmits motion from the handle or controlling device to the disc. The stem typically passes through the when present. In some cases, the stem and the disc can be combined in one piece, or the stem and the handle are combined in one piece.The motion transmitted by the stem may be a linear, a rotational, or some combination of these (Angle valve using torque reactor pin and Hub Assembly). The valve and stem can be threaded such that the stem can be screwed into or out of the valve by turning it in one direction or the other, thus moving the disc back or forth inside the body.

is often used between the stem and the bonnet to maintain a seal. Some valves have no external control and do not need a stem as in most.Valves whose disc is between the seat and the stem and where the stem moves in a direction into the valve to shut it are normally-seated or front seated.

Valves whose seat is between the disc and the stem and where the stem moves in a direction out of the valve to shut it are reverse-seated or back seated. These terms don't apply to valves with no stem or valves using rotors. X750 Gasketsare the mechanical seals, or packings, used to prevent the leakage of a gas or fluids from valves.Valve ballsA valve ball is also used for severe duty, high-pressure, applications. They are typically made of,. They can also be made of different types of plastic, such as, or.SpringMany valves have a for spring-loading, to normally shift the disc into some position by default but allow control to reposition the disc. Commonly use a spring to keep the valve shut, but allow excessive pressure to force the valve open against the spring-loading. Are normally used.

Typical spring materials include, and for high temperature applications X750.TrimThe internal elements of a valve are collectively referred to as a valve's trim. According to API Standards 600, 'Steel Gate Valve-Flanged and Butt-welding Ends, Bolted Bonnets', the trim consists of stem, seating surface in the body, gate seating surface, bushing or a deposited weld for the backseat and stem hole guide, and small internal parts that normally contact the service fluid, excluding the pin that is used to make a stem-to-gate connection (this pin shall be made of an austenitic stainless steel material).Valve operating positions. A for cooling, on a marine.

Seacocks are usually ball valves, but may be other types as well.Valve positions are operating conditions determined by the position of the disc or rotor in the valve. Some valves are made to be operated in a gradual change between two or more positions. And allow fluid to move in 2 or 1 directions respectively.Two-port valvesOperating positions for 2-port valves can be either shut (closed) so that no flow at all goes through, fully open for maximum flow, or sometimes partially open to any degree in between.

Many valves are not designed to precisely control intermediate degree of flow; such valves are considered to be either open or shut. Some valves are specially designed to regulate varying amounts of flow. Such valves have been called by various names such as regulating, throttling, metering,.

For example, needle valves have elongated conically-tapered discs and matching seats for fine flow control. For some valves, there may be a mechanism to indicate by how much the valve is open, but in many cases other indications of flow rate are used, such as separate.In plants with remote-controlled process operation, such as oil refineries and petrochemical plants, some 2-way valves can be designated as normally closed (NC) or normally open (NO) during regular operation. Examples of normally-closed valves are, which are only opened while a sample is taken. Other examples of normally-closed valves are, which are kept open when the system is in operation and will automatically shut by taking away the power supply. This happens when there is a problem with a unit or a section of a fluid system such as a in order to isolate the problem from the rest of the system.

Examples of normally-open valves are purge-gas supply valves or emergency-relief valves. When there is a problem these valves open (by switching them 'off') causing the unit to be flushed and emptied.Although many 2-way valves are made in which the flow can go in either direction between the two ports, when a valve is placed into a certain application, flow is often expected to go from one certain port on the upstream side of the valve, to the other port on the downstream side.

Are variations of valves in which flow is controlled to produce a certain downstream, if possible. They are often used to control flow of gas from a.

A back-pressure regulator is a variation of a valve in which flow is controlled to maintain a certain upstream pressure, if possible.Three-port valves. Schematic 3 way ball valve: L-shaped ball right, T-shaped leftValves with three ports serve many different functions. A few of the possibilities are listed here.come with a T- or L- shaped fluid passageways inside the rotor. The T valve might be used to permit connection of one inlet to either or both outlets or connection of the two outlets. The L valve could be used to permit disconnection of both or connection of either but not both of two inlets to one outlet.automatically connect the higher pressure inlet to the outlet while (in some configurations) preventing flow from one inlet to the other.produce a variable mixture of hot and cold water at a variable flow rate under control of a single handle.mix hot and cold water to produce a constant temperature in the presence of variable pressures and temperatures on the two input ports.Four-port valves.

A sailor aboard a ship operates the wheel controlling a.Many valves are controlled manually with a attached to the stem. If the handle is turned between operating positions, the valve is called a quarter-turn valve. Butterfly, ball valves, and plug valves are often quarter-turn valves. If the handle is circular with the stem as the axis of rotation in the center of the circle, then the handle is called a handwheel. Valves can also be controlled by attached to the stem. They can be electromechanical actuators such as an or, pneumatic actuators which are controlled by, or actuators which are controlled by the of a liquid such as oil or water.

Actuators can be used for the purposes of automatic control such as in washing machine cycles, remote control such as the use of a centralised, or because manual control is too difficult such as when the valve is very large. Pneumatic actuators and hydraulic actuators need pressurised air or liquid lines to supply the actuator: an inlet line and an outlet line. Are valves which are used to control other valves. Pilot valves in the actuator lines control the supply of air or liquid going to the actuators.The in a water tank is a liquid level-actuated valve. When a high water level is reached, a mechanism shuts the valve which fills the tank.In some valve designs, the pressure of the flow fluid itself or pressure difference of the flow fluid between the ports automatically controls flow through the valve.Other considerationsValves are typically rated for maximum and by the manufacturer. The wetted materials in a valve are usually identified also.

Some valves rated at very high pressures are available. When a designer, engineer, or user decides to use a valve for an application, he/she should ensure the rated maximum temperature and pressure are never exceeded and that the wetted materials are compatible with the fluid the valve interior is exposed to.

In Europe, valve design and pressure ratings are subject to statutory regulation under the 97/23/EC (PED).Some fluid system designs, especially in chemical or power plants, are schematically represented in. In such diagrams, different types of valves are represented by certain.Valves in good condition should be leak-free. However, valves may eventually wear out from use and develop a, either between the inside and outside of the valve or, when the valve is shut to stop flow, between the disc and the seat.

A particle trapped between the seat and disc could also cause such leakage.Images.

SAMSON Group top guided and cage guided globe control valves are suited for multiple applications in many industries. Manufactured with a modular design, the valves meet ANSI, API, ASME, ISO, DIN, and JIS standards.Our valves can be ordered in globe, angle, and three-way bodies in a wide range of sizes and pressure classes made of standard, exotic, or PFA/PTFE lined materials with welded, threaded, or flanged ends. Depending on your need, the valves can be modified for continuous control or on/off with added limit switches or solenoid valves that meet SIL requirements.SAMSON globe control valves provide measured control of your fluid processes such as non-corrosive, corrosive and erosive media, and steam, hygienic and aseptic fluids. Using pneumatic or electric actuators and digital positioners, the valves integrate with diagnostic control systems through HART, Profibus, and Foundation Fieldbus protocols.Even under the most extreme conditions, SAMSON valves maintain their reputation for high quality. Rising costs must be monitored and controlled.

Regulations and laws become more restrictive and complex. You, our customers, rightfully expect improving technology to meet your process needs. We at SAMSON continue to innovate while maintaining high quality and service.