Air Valve

Ball Valve

Types of Ball Valve

  • Duplex ball valve

There are five general body styles of ball valves: single body, three-piece body, split body, top entry, and welded. The difference is based on how the pieces of the valve—especially the casing that contains the ball itself are manufactured and assembled. The valve operation is the same in each case.

In addition, there are different styles related to the bore of the ball mechanism itself.

Ball valves in sizes up to 2 inch generally come in single piece, two or three piece designs. One piece ball valves are almost always reduced bore, are relatively inexpensive and generally are throw-away. Two piece ball valves are generally slightly reduced (or standard) bore, they can be either throw-away or repairable. The 3 piece design allows for the center part of the valve containing the ball, stem & seats to be easily removed from the pipeline. This facilitates efficient cleaning of deposited sediments, replacement of seats and gland packings, polishing out of small scratches on the ball, all this without removing the pipes from the valve body. The design concept of a three piece valve is for it to be repairable.

  • Full port

A full port or more commonly known full bore ball valve has an over-sized ball so that the hole in the ball is the same size as the pipeline resulting in lower friction loss. Flow is unrestricted but the valve is larger and more expensive so this is only used where free flow is required, for example in pipelines which require pigging.

  • Reduced port

In Reduced port (more commonly known as reduced bore) ball valves, flow through the valve is one pipe size smaller than the valve's pipe size resulting in flow area being smaller than pipe. As the flow discharge remains constant and is equal to area of flow times velocity, the velocity increases with reduced area of flow.

  • V port

A V port ball valve has either a 'v' shaped ball or a 'v' shaped seat. This allows the orifice to be opened and closed in a more controlled manner with a closer to linear flow characteristic. When the valve is in the closed position and opening is commenced the small end of the 'v' is opened first allowing stable flow control during this stage. This type of design requires a generally more robust construction due to higher velocities of the fluids, which might damage a standard valve. These can be referred to as a type of control valve but are not as accurate as a balancing valve, needle valve, globe valve, or pressure regulating valve.

  • Cavity filler

Many industries encounter problem with residues in the ball valve. Where the fluid is meant for human consumption, residues may also be health hazard, and when where the fluid changes from time to time contamination of one fluid with another may occur. Residues arise because in the half open position of the ball valve a gap is created between the ball bore and the body in which fluid can be trapped. To avoid the fluid getting into this cavity, the cavity has to be plugged, which can be done by extending the seats in such a manner that it is always in contact with the ball. This type of ball valve is known as Cavity Filler Ball Valve.

There are a few types of ball valves lateral movement of the ball:

  • Trunnion

A trunnion ball valve has additional mechanical anchoring of the ball at the top and the bottom, suitable for larger and higher pressure valves (say, above 10 cm and 40 bars).

  • A floating ball valve is one where the ball is not held in place by a trunnion. In normal operation, this will cause the ball to float downstream slightly. This causes the seating mechanism to compress under the ball pressing against it. Furthermore, in some types, in the event of some force causing the seat mechanism to dissipate (such as extreme heat from fire outside the valve), the ball will float all the way to metal body which is designed to seal against the ball providing a somewhat failsafe design.  

Manually operated ball valves can be closed quickly and thus there is a danger of water hammer. Some ball valves are equipped with an actuator that may be pneumatically, hydraulically or motor operated. These valves can be used either for on/off or flow control. A pneumatic flow control valve is also equipped with a positioner which transforms the control signal into actuator position and valve opening accordingly.

  • Multiport

    • Three- and four-way have an L- or T-shaped hole through the middle. The different combinations of flow are shown in the figure. It is easy to see that a T valve can connect any pair of ports, or all three, together, but the 45 degree position which might disconnect all three leaves no margin for error. The L valve can connect the center port to either side port, or disconnect all three, but it cannot connect the side ports together.

    • Multi-port ball valves with 4 ways, or more, are also commercially available, the inlet way often being orthogonal to the plane of the outlets. For special applications, such as driving air-powered motors from forward to reverse, the operation is performed by rotating a single lever four-way valve. The 4-way ball valve has two L-shaped ports in the ball that do not interconnect, sometimes referred to as an "×" port.

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A ball valve is a form of quarter-turn valve which uses a hollow, perforated and pivoting ball (called a "floating ball") to control flow through it. It is open when the ball's hole is in line with the flow and closed when it is pivoted 90-degrees by the valve handle. The handle lies flat in alignment with the flow when open, and is perpendicular to it when closed, making for easy visual confirmation of the valve's status.

Ball valves are durable, performing well after many cycles, and reliable, closing securely even after long periods of disuse. These qualities make them an excellent choice for shutoff applications, where they are often preferred to gates and globe valves, but they lack their fine control in throttling applications.

The ball valve's ease of operation, repair, and versatility lend it to extensive industrial use, supporting pressures up to 1000 bar andtemperatures up to 752°F (500°C), depending on design and materials used. Sizes typically range from 0.2 to 48 inches (0.5 cm to 121 cm). Valve bodies are made of metal, plastic, or metal with a ceramic; floating balls are often chrome plated for durability.

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Ball valves can be used in a variety of applications and markets, such as transmission and storage, gas processing, industrial, and many more. Ball Valves provide reliable leak protection which is especially beneficial in gas applications. Ball valves have low pressure drop and can open and close quickly. 

Chemical and Petrochemical Complexex

  • Low Differential Pressure Control

  • Emission Control

  • Handle Highly Viscous Fluids. Abrasive Slurries or Corrosive as well as non-corrosives in processes and Storing Facilities

Power Industry

 

  •     Boiler Feed Water Control

  •     Control abd Shot-off for Steam

  •     Burner Trip Valves

  •     Sluicing Valves for Feding Coal into Pressurised Combustore and for extracting fly ash

Gas and Oil Production

  •     Subsea Isolation and Shut-down

  •     Well-Head Isolation

  •     Piping Suege Control

  •     Secondary and Enhanced Oil Recovery

  •     Processing Separration

  •     Transmission and Distribution

  •     Storage Tang

Pulp and paper Industry

  •     Pulp Mill Diagesters

  •     Shut-off Valves

  •     Batch-Digester Blow Service

  •     Liquor Fill and Circulation

  •     Lime Mud (Slrry) Flow Contro

  •     Dilution Water Control

Other Common area for the application of ball valves include: Food Industry. Water supply and transport, Marine and soilds transport.

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Micro-resistance Ball Valve uses the rubber covered roller as the disc, which, under the action of the medium, can roll up and down along with the sliding path inside the valve so as to open or close it. And it features by the big flow, small flow-resistance loss, good tightness, silent close and reduced water shock wave. It can be mountable vertically or horizontally and used on the outlet of the water pump of the cold-water, hot-water, industrial and living sludge pipe networks to prevent the medium from going back.

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Non Return Valve

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Check Valve, Clack Valve, Non-Return Valve or One-Way Valve is a Valve that normally allows Fluid (Liquid or Gas) to flow through it in only one direction.

Check Valves are self-activating safety valves that permit gases and liquids to flow in only one direction. The purpose of a check valve is to prevent process flow from reversing in the system which could damage equipment or upset the process. They are classified as one-way directional valves. Check Valves are commonly found protecting pumps in liquid applications or compressors in gas systems where backflow could cause the pump or compressor to shut down. They are also applied in process systems that have varying pressures, which must be kept separate. They do not need an outside power supply to operate since they use the pressure drop created by the media flow.

Pressure Relief Valve

Spring Loaded Pressure Relief Valve

The basic spring loaded pressure Relief Valve has been developed to meet the need for a simple, reliable, system actuated device to provide overpressure protection. The image on the right shows the construction of a spring loaded pressure Relief Valve. The Valve consists of a Valve inlet or nozzle mounted on the pressurized system, a disc held against the nozzle to prevent flow under normal system operating conditions, a spring to hold the disc closed, and a body/Bonnet to contain the operating elements. The spring load is adjustable to vary the pressure at which the Valve will open.

When a pressure Relief Valve begins to lift, the spring force increases. Thus system pressure must increase if lift is to continue. For this reason pressure Relief Valves are allowed an overpressure allowance to reach full lift. This allowable overpressure is generally 10% for Valves on unfired systems. This margin is relatively small and some means must be provided to assist in the lift effort. Most pressure Relief Valves, therefore, have a secondary control chamber or huddling chamber to enhance lift. As the disc begins to lift, fluid enters the control chamber exposing a larger area of the disc to system pressure.

This causes an incremental change in force which overcompensates for the increase in spring force and causes the Valve to open at a rapid rate. At the same time, the direction of the fluid flow is reversed and the momentum effect resulting from the change in flow direction further enhances lift. These effects combine to allow the Valve to achieve maximum lift and maximum flow within the allowable overpressure limits. Because of the larger disc area exposed to system pressure after the Valve achieves lift, the Valve will not close until system pressure has been reduced to some level below the set pressure. The design of the control chamber determines where the closing point will occur. The difference between the set pressure and the closing point pressure is called blowdown and is usually expressed as a percentage of set pressure.

Balanced Bellows Valves and Balanced Piston Valves

When superimposed back pressure is variable, a balanced bellows or balanced piston design is recommended. A typical balanced bellow is shown on the right. The bellows or piston is designed with an effective pressure area equal to the seat area of the disc. The Bonnet is vented to ensure that the pressure area of the bellows or piston will always be exposed to atmospheric pressure and to provide a telltale sign should the bellows or piston begin to leak. Variations in back pressure, therefore, will have no effect on set pressure. Back pressure may, however, affect flow.

Other Designs of Pressure Relief Valves

Safety Valve.

A safety Valve is a pressure Relief Valve actuated by inlet static pressure and characterized by rapid opening or pop action. (It is normally used for steam and air services.)

  • Low-Lift Safety Valve

A low-lift safety Valve is a safety Valve in which the disc lifts automatically such that the actual discharge area is determined by the position of the disc.

  • Full-Lift Safety Valve

A full-lift safety Valve is a safety Valve in which the disc lifts automatically such that the actual discharge area is not determined by the position of the disc.

Relief Valve

A Relief Valve is a pressure relief device actuated by inlet static pressure having a gradual lift generally proportional to the increase in pressure over opening pressure. It may be provided with an enclosed spring housing suitable for closed discharge system application and is primarily used for liquid service.

Safety Relief Valve

A safety Relief Valve is a pressure Relief Valve characterized by rapid opening or pop action, or by opening in proportion to the increase in pressure over the opening pressure, depending on the application and may be used either for liquid or compressible fluid.

  • Conventional Safety Relief Valve

A conventional safety Relief Valve is a pressure Relief Valve which has its spring housing vented to the discharge side of the Valve. The operational characteristics (opening pressure, closing pressure, and relieving capacity) are directly affected by changes of the back pressure on the Valve.

  • Balanced Safety Relief Valve

A balanced safety Relief Valve is a pressure Relief Valve which incorporates means of minimizing the effect of back pressure on the operational characteristics (opening pressure, closing pressure, and relieving capacity).

Pilot-Operated Pressure Relief Valve

A pilotoperated pressure Relief Valve is a pressure Relief Valve in which the major relieving device is combined with and is controlled by a self-actuated auxiliary pressure Relief Valve.

Power-Actuated Pressure Relief Valve

A poweractuated pressure Relief Valve is a pressure Relief Valve in which the major relieving device is combined with and controlled by a device requiring an external source of energy.

Temperature-Actuated Pressure Relief Valve

A temperature-actuated pressure Relief Valve is a pressure Relief Valve which may be actuated by external or internal temperature or by pressure on the inlet side.

Vacuum Relief Valve

A vacuum Relief Valve is a pressure relief device designed to admit fluid to prevent an excessive internal vacuum; it is designed to reclose and prevent further flow of fluid after normal conditions have been restored.

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A pressure Relief Valve is a safety device designed to protect a pressurized vessel or system during an over pressure event. An overpressure event refers to any condition which would cause pressure in a vessel or system to increase beyond the specified design pressure or maximum allowable working pressure (MAWP). The primary purpose of a pressure Relief Valve is protection of life and property by venting fluid from an overpressurized vessel.Many electronic, pneumatic and hydraulic systems exist today to control fluid system variables, such as pressure, temperature and flow. Each of these systems requires a power source of some type, such as electricity or compressed air in order to operate. A pressure Relief Valve must be capable of operating at all times, especially during a period of power failure when system controls are nonfunctional. The sole source of power for the pressure Relief Valve, therefore, is the process fluid. Once a condition occurs that causes the pressure in a system or vessel to increase to a dangerous level, the pressure Relief Valve may be the only device remaining to prevent a catastrophic failure. Since reliability is directly related to the complexity of the device, it is important that the design of the pressure Relief Valve be as simple as possible.

The pressure Relief Valve must open at a predetermined set pressure, flow a rated capacity at a specified overpressure, and close when the system pressure has returned to a safe level. Pressure Relief Valves must be designed with materials compatible with many process fluids from simple air and water to the most corrosive media. They must also be designed to operate in a consistently smooth and stable manner on a variety of fluids and fluid phases.

Safety valves (sometimes called relief valves or safety relief valves) are spring loaded devices. Normally, the valve is forced shut by the spring, but when the pressure rises, the force of the spring is overcome, forcing the valve open. This releases fluid, relieving the pressure. Once the process pressure is reduced, the safety valve will re seal, limiting the amount of material released.

Pressure and / or vacuum relief valves are used on liquid storage tanks and other process vessels or systems to prevent structural damage due to excess internal pressure or vacuum. Storage tanks are pressurized when liquid is pumped in, compressing the existing vapor or when rising temperatures cause increased evaporation or expansion of existing vapor. Conversely, a vacuum condition may be created when pumping out or due to falling temperature. To prevent tank damage, vapor must be allowed into or out of the tank at specified pressure / vacuum conditions. The volume rate of venting depends upon the tank size, volatility of the tank contents, the pumping rates and the temperature.

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We pressure relief valves help meet the requirements of ANSI/ASHRAE 15-2001 Safety Standard for Refrigeration Systems as well as other worldwide codes. This standard requires pressure vessels of all refrigeration systems to be protected by a pressure relief device or other approved means to safely relieve pressure in the event of fire or other abnormal conditions. Once installed, a properly selected we pressure relief valve is ready to vent to atmosphere any temporary excessive overpressure inside of a vessel. After discharge, these valves will attempt to reseat to minimize loss of refrigerant. However, once any relief valve has discharged, it must be replaced as soon as possible because debris may have settled on the seat during discharge.

We pressure relief valves should be connected to the.... 

vapor space of refrigerant vessels,

  • Heat Exchangers,

  • Oil Pots,

  • Oil Stills,

  • Pilot Receivers,

and elsewhere as may be required by various codes. Where dual pressure relief valves are required, we offers the three-way valves and other components necessary for assembly. Rupture disc assemblies are required when using we pressure relief valves for halocarbon applications because the high cost of such refrigerants demands extreme tightness, These pressure relief valves offer a cartridge style design for ease of replacement without disturbing the piping. EZ-SRV pressure relief valves are available in pressure ratings to 600 psi.

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Tank protection equipment typically includes an operating valve which is designed to provide pressure/vacuum relief under normal pump in/out and thermal breathing conditions. An emergency relief valve can also provide both pressure and vacuum relief and normally it is sized to provide pressure relief if there is a fire in the immediate vicinity of the tank. It may also be sized by the tank designer to provide protection in the event of equipment failure (such as the rupture of a process steam line or an inert gas ba nketing system failing “wide open”) or operator error.

A typical tank installation is shown n Figure 1 which includes the following Groth products:

  • Pressure/Vacuum Weight Loaded Valve

  • Gas Blanketing Regulator

  • Emergency Pressure Relief Valve

Pressure Relief

As the pressure in the storage tank increases, the vacuum pallet is held shut. When the set pressure is reached, the pressure pallet lifts and relieves tank pressure to the atmosphere (or to a header if it is a pipe away valve). See Figure 2.

Vacum Relief

As a vacuum is drawn in the storage tank (for example, when fluid is being pumped out), the pressure pallet is held shut. When the vacuum setting is reached, the vacuum pallet lifts and air is drawn into the tank from the atmosphere. See Figure 3.

 

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Needle Valve

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A Needle Valve is a type of valve having a small port and a threaded, needle-shaped plunger. It allows precise regulation of flow, although it is generally only capable of relatively low flow rates.

Needle valves have a slender, tapered point at the end of the valve stem that is lowered through the seat to restrict or block flow. Fluid flowing through the valve turns 90 degrees and passes through an orifice that is the seat for a rod with a cone shaped tip. These small valves are widely used to accurately regulate the flow of liquids and gases at low flow rates. The fine threading of the stem and the large seat area allow for precise resistance to flow. Needle valves are used to control flow into delicate gauges, which might be damaged by sudden surges of fluid under pressure.

Needle valves are also used in situations where the flow must be gradually brought to a halt and at other points where precise adjustments of flow are necessary or where a small flow rate is desired. They can be used as both on/off valves and for throttling service.

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Applications

Needle valves are used in almost every industry in an incredibly wide range of applications - anywhere control or metering of steam, air, gas, oil, water or other non-viscous liquids is required.

  • Industries 

  • Zoological Sciences

  • Gas and Liquid Dispensation

  • Instrumentation Control

  • Cooling

  • Power Generation

Needle Valves should be avoided in applications where the media is viscous, or in the dispensation of slurries. The small flow orifice can easily trap thick materials or solids and become blocked.

Globe Valve

Body Designs of Globe Valves

There are three primary body designs for Globe valves, namely:

  • Tee Pattern or Z-body

  • Angle Pattern

  • Wye Pattern or Y-body body

Tee Pattern  or Z-shaped Globe Valve Design

Tee Pattern Globe valve design is the most common body type, with a Z-shaped diaphragm. The horizontal setting of the seat allows the stem and disk to travel perpendicular to the horizontal line. This design has the lowest coefficient of flow and higher pressure drop. They are used in severe throttling services, such as in bypass lines around a control valve. Tee-pattern Globe valves may also be used in applications where pressure drop is not a concern and throttling is required.

Angle Body Globe Valve

Angle Pattern Globe valves design is a modification of the basic Tee Pattern Globe valve. The ends of this Globe valve are at an angle of 90 degrees, and fluid flow occurs with a single 90 degrees turn. They have a slightly lower coefficient of flow than wye-pattern Globe valves. They are used in applications that have periods of pulsating flow because of their capability to handle the slugging effect of this type of flow.

Wye Pattern Globe valves

Wye Pattern Globe valves design, is an alternative for the high pressure drop, inherent in Globe valves. Seat and stem are angled at approximately 45 degrees, what gives a straighter flowpath at full opening and offer the least resistance to flow. They can be cracked open for long periods without severe erosion. They are extensively used for throttling during seasonal or startup operations. They can be rod through to remove debris when used in drain lines that are normally closed.

 

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Introduction of Globe Valves

As their name suggests, globe valves are linear motion valves with rounded globular shaped bodies. Since their shape is similar to other valve bodies, positive identification must be made based on internal piping. Recently globe valves have lost their traditional round body-shape. Globe valves have many advantages and disadvantages for users. They have excellent and precise throttling ability for high-pressure systems. The disadvantages include low-flow coefficients and a longer operating time because the operator must turn the handle and stem many times to ensure the valve is completely open or completely closed. Globe valves can be used in systems that require frequent stroking, vacuum, and systems that have a wide range of temperature extremes

A Globe valves is a linear motion valve and are primarily designed to stop, start and regulate flow. The disk of a Globe valve can be totally removed from the flowpath or it can completely close the flowpath.

Conventional Globe valves may be used for isolation and throttling services. Although these valves exhibit slightly higher pressure drops than straight=through valves (e.g., gate, plug, ball, etc.), they may be used where the pressure drop through the valve is not a controlling factor.

Because the entire system pressure exerted on the disc is transferred to the valve stem, the practical size limit for these valves is NPS 12 (DN 300). Globe valves larger than NPS 12 (DN 300) are an exception rather than the rule. Larger valves would require that enormous forces be exerted on the stem to open or close the valve under pressure. Globe valves in sizes up to NPS 48 (DN 1200) have been manufactured and used.

Globe valves are extensively employed to control flow. The range of flow control, pressure drop, and duty must be considered in the design of the valve to avert premature failure and to assure satisfactory service. Valves subjected to high-differential pressure-throttling service require specially designed valve trim.

Generally the maximum differential pressure across the valve disc should not exceed 20 percent of the maximum upstream pressure or 200 psi (1380 kPa), whichever is less. Valves with special trim may be designed for applications exceeding these differential pressure limits.

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Typical Applications of Globe valves

The following are some of the typical applications of Globe valves:

  • Cooling water systems where flow needs to be regulated

  • Fuel oil system where flow is regulated and leaktightness is of importance

  • High-point vents and low-point drains when leaktightness and safety are major considerations

  • Feedwater, chemical feed, condenser air extraction, and extraction drain systems

  • Boiler vents and drains, main steam vents and drains, and heater drains

  • Turbine seals and drains

  • Turbine lube oil system and others

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A globe valve, different from ball valve, is a type of valve used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body.

Globe valves are named for their spherical body shape with the two halves of the body being separated by an internal baffle. This has an opening that forms a seat onto which a movable plug can be screwed in to close (or shut) the valve. The plug is also called a disc ordisk. In globe valves, the plug is connected to a stem which is operated by screw action using a handwheel in manual valves. Typically, automated globe valves use smooth stems rather than threaded and are opened and closed by an actuator assembly.

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Gate Valve

 There are Two Type of Gate Valve

  • The Rising Stem Gate Valve

Cast Iron Gate Valve is designed with straight through bore type with rising stem, outside screw & yoke, bolted bonnet and stainless steel trim. The open and closed position of the valve is easily distinguished by the stem position. The Wedge is replaceable without needing to remove the valve from the pipelines. 

Cast Iron Gate Valve allows for two-way flow direction and used for closing or opening the medium flow. This valve can be installed in horizontal and vertical positions in the piping systems. It is widely used in process industries such as Palm Oil and Refinery Plant, Food Industries, Petrochemical, Fire Protection System, Power Plant and Cooling System. 

  • Non-rising Stem Gate Valve 

Used in fire protection systems for on/off operation, Tyco Resilient Seated Gate Valves incorporate high strength stainless steel stems, dezincification resistant copper alloy components, high-grade elastomers and quality coating systems. The lightweight ductile iron body weighs less than conventional cast iron valves, which allows for easier handling on site and reduces shipping costs. A fully encapsulated EPDM ductile iron wedge is intended to achieve bubble-tight sealing. Components that are not designed to be inherently corrosion resistant are coated with a thermally applied fusion-bonded epoxy.

The gate sealing design combines wedge and compression mechanisms to achieve low torque, drop tight sealing. The stem seal arrangement incorporates five separate O-rings designed to provide a lifetime seal. Available end connections include flange-by-flange, flange-bygroove and groove-by-groove configurations. 

There are Two Type of Gate Valve Body

 

Body acts as an enclosure to stem and disc assembly and flow passage for the fluid to flow.  in most of the gate valve body construction ,the upper portion is extended to enclose the disc when the valve is at fully open condition. This provision can also give in bonnet by changing the bonnet design ,if a short body is prefered.

  • Casted Body

Casted valve bodies are mainly used for large sized valve where other fabrication process not feasible. 

  • Forged Body

Forged body can use  for smaller sized high pressure application of gate valves.

There are Two Type of Gate/Disc

 

Parallel Gate

For a parallel gate both the faces of the gate is parallel

  • Knife Gate

Knife gate is a parallel gate having sharp bottom edge used in slurry handling pipelines to separate the slurry by slicing the flow.  

  • Through Conduit Gate

A through hole is drilled in the gate.to achieve full port see more details about full port double expanding through conduit gate valve.  

Wedge Gate

The gate design is in the form of a wedge having two flat inclined surfaces.Two are inclined but might have a slight angular mismatch. Sealing will be in tight contact with the wedge by wedge action. Due to the inclined contact between the wedge and the seat, an immediate disengagement without any sliding action between the wedge  and the sealing ,when the gate starts to travel upward during valve opening. This reduces the wear due rubbing action and increases the life of sealing and gate compared to parallel gates.

  • Single Solid Wedge Gate

This is the most common and stronger wedge design. Due to the simple construction of the wedge, the fabrication cost is much less compared to other wedge designs.Solid wedge design can be assembled and operated in any orientation and can used in any fluid application even for a turbulent flow.

Solid wedge working in high temperature applications like steam pipelines may undergo slight expansion due to the temperature gradient and will induce more compression forces during  tight shut off condition and undergoes deflection as shown in figure. This may cause seating mismatch and leads to leakage.This can be solved using split or double plate wedge design by inducing wedge flexing. 

  • Split Flexible Wedge gate

The solid wedge is stilted all round the perimeter.This makes the single piece wedge into two piece which can flex  to correct any angular miss match between the wedge and seating and more tight seating as shown in figure without loosing much  strength of the wedge.

  • Double plate Wedge Design

 Double plate design having two plates assembled using ball and socket to adjust any mismatch/alignment problems or any solid entrapment like dirt between the wedge and seating.  This types of wedges mainly used for non condensing gas and liquid applications.

 

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  • The Gate valve is a linear actuating  valve used as flow isolater in a fluid pipeline.  As the name says the gate valve, a flat  circular or rectangular plate acts as a 'gate' in a pipeline. We call this plate as disc ,gate or wedge. When the valve actuates down the gate slice the fluid  to total shut off .The disc can moved up fully into the upper portion of the body and results no hindrance to the fluid flow cross section area.  This  makes the valve  full open with very less pressure drop.

Gate valves (also known as knife valves or slide valves) are linear motion valves in which a flat closure element slides into the flow stream to provide shut-off. They are one of the most common valves used.

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Gate valves and knife valves are advantageous in applications involving slurries, as their “gates” can cut right through the slurry. They are also used in applications that involve viscous liquids such as heavy oils, light grease, varnish, molasses, honey, cream and other non-flammable viscous liquids. They are available in large sizes to better handle thick flow. However, gate valves do have low-pressure limitations, and are not optimal in applications that require cleanliness or sanitary conditions.  They are excellent for use anywhere a shutoff valve is needed. When needed, they can also be used where throttling capabilities are desired, although this is not generally recommended as erosion of the seat and disc occurs due to the vibrations of the disk in throttling applications. 

Gate valves and knife valves are designed to minimize pressure drop across the valve in the fully opened position and stop the flow of fluid completely. The direction of fluid flow does not change, and the diameter through which the process fluid passes is essentially equal to that of the pipe. Hence, they tend to have minimal pressure drop when opened fully.

Gate valves are used in many industrial applications including the oil and gas industry, pharmaceuticals, manufacturing, automotive, and marine.

Non-rising stem gate valves are very popular on ships, in underground applications, or where vertical space is limited because they don't take up extra space. Gate valves can be used in demanding environments such as high temperature and high pressure environments. They are often seen in power plants, water treatments, mining, and offshore applications.

Valve Applications

Valves serve a variety of purposes in the industrial, engineering, manufacturing and scientific communities. Selecting the right valve can determine the success or failure of the system or process.

The main purpose of a valve is to control media flow through a system. The valve may be used to start, stop, or throttle the flow to ensure safe and efficient operation of the process. To learn more about the mechanisms that valves use to control flow, please read Valve Types.

Industries

Valves play a large role in most industries. They are used in many parts of daily mechanical devices, including in HVAC and water systems in an office and the gasoline mechanism for an automobile. Below are a few examples of the many industries in which valves play a major role in proper operation.

  • Pipelines

This use is an essential aspect of many industries, but there are hundreds of thousands of miles of crucial pipelines that transport media from its source to the place where it will be transformed into its final product. This media could include piping for crude oil and gas, both onshore and offshore. Valves are used to optimize the pipeline operating conditions, and can be found in the upstream, midstream and downstream section of the piping. Upstream starts at the bottom of the hole in the ground and covers everything on the wellhead up to the choke. In this case, the choke is a specialized globe valve that is mounted on the wellhead to regulate the output of the well. Midstream starts at the output of the choke and ends at the fence of the final destination (usually a refinery). Downstream is everything inside the area of the destination. The most important factor to consider when selecting a valve for a pipeline application is whether the valve is piggable – that is, the inside is designed to be cleaned or inspected.

  • Oil and Gas

The oil and gas industry is a subset of the pipelines category. Due to the high demand for oil and gas, deeper wells, longer pipelines, and lower production costs have become necessary. Along with the need for an inexpensive valve, the device must also be tougher, last longer, and perform better to meet the demands of the industry. Valve service environments and operating conditions are often extreme with high temperatures (greater than 1,500°F) and high pressure (greater than 25,000 psig) or cryogenic and very low pressure applications. Another feature important to valves used in the oil and gas industry is the capacity for remote control.

  • Food and Beverage

The food and beverage industry is a large and growing industry with an increasing need for parts and products that keep plants running smoothly .The industry’s many challenges, including safety concerns, have prompted strict material requirements for the valves used in these plants. There are two classifications for valves in the food and beverage industry: those in direct contact with food materials and those handling utility services (i.e. steam, water). For valves which come into direct contact with food, there are regulations in place (issued by such organizations as the FDA) which require that the inside of the valve be smooth enough to avoid trapping particles or bacterial accumulation. Valves made of a soft material must not absorb or hold any product going through the valve. These standards also specify that there should not be dead volume in the valve or crevices where material can be trapped to avoid decay or stagnate. Valves in the food and beverage industry do not face the high pressures or highly corrosive materials that are present in other industries.

  • Biopharm Industry

The biopharm industry is part of the larger chemical processing industry. The most important feature of valves used in this industry is their ability to be cleaned and sterilized. The chemical processing industry is responsible for processing raw materials into products. Since chemical processing often involves reactions using pressure and/or heat, and could cause toxic by-products, the media in this industry tends to be highly corrosive and abrasive. The valves need to be able to tolerate the nature of the media, as well as offer precise flow control and high leakage protection to protect against spills and cross-contamination.

  • Marine Industry

Valves play a critical role in the marine industry. As ships become larger and are used more frequently, they require the ability to generate power, treat and manage wastewater and control HVAC, as well as perform their required tasks. The size and application of the ship will determine the different types and number of valves on board. Valves are used to regulate the loading and storage of a ship’s power supply, provide water for fire-fighting capabilities, handle and processes wastewater and store any liquid cargo, among many other applications. Any valve that processes sea water must be durable, and all marine valves must be reliable due to lack of resources once out at sea.

 

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The closure element of a gate valve is a replaceable disk. To open the valve, the disk is completely removed from the stream and offers virtually no resistance. Therefore, there is little pressure drop across the open gate valve. A fully closed gate valve provides good sealing due to the 360° disk-to-seal ring contact surface. Proper mating of a disk to the seal ring ensures there is very little or no leakage across the disk when the gate valve is closed.

They are used to start or stop a flow completely. They should not be used to control flow rate. Using a gate valve in a partially open position can damage the valve. Fluid flow across the gate causes erosion to the gate making it impossible to seal well against its seat.
Fluid can flow through most gate valves in either direction.
The closing element in a gate valve is a wedge-shaped disc or gate attached to the end of the stem, as shown in Figure. The gate fits into a wedge-shaped seat in the valve body to stop flow through the valve, as shown in Figure.

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Diverter Valve

There are two main types of diverter valves. Both types switch flow from one line into one of two outlets.

One type is Wye Line Diverter, which contains a hinged disc at the intersection to close one of the two outlets. This type of valve is best for handling dry bulk materials in dilute phase vacuum or pressure pneumatic conveying systems. They are designed to eliminate material cross contamination and buildup. 

The second type of diverter is primarily used for liquid services. Instead of using moving parts (like the disc in the wye line diverter), the flow stream is altered by pneumatic pressure differential.

There are 3 Standard types of Diverter Valves 

  1. Y type Diverter Valve

  2. T type Diverter Valve

  3. R type Diverter Valve

  • Y type Diverter Valve

A standard Y type diverter valve with one inlet and two outlets. The process flow enters the top connection and the outlet flow is to either or both of the outlet lines existing in parallel below the valve body.

  • T type Diverter Valve

A standard T type diverter valves. In all designs the angular relationship of the outlet ports may be changed to meet the requirements of the installation. Special designs are also available for large size valves or high flow rates.

  • R type Diverter Valve

The R type diverter valve is similar to the Y type except that the outlets are at right angles to the inlet flow. This design frequently utilises rotating, contoured pistons/rams on one or both sides to assure smooth, unobstructed flow. This is a particularly useful feature for highly viscose media such as polymer or heavy gas oil with high solids content.

Choice of Diverter Valve configuration or type depends on a number of factors including flow characteristics of the medium, available space, piping layout and process or application requirements.

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Diverter Valves are processing valves designed to direct flow from an inlet to one of two or more outlets. They can also be used for flow control and to converge two lines into one. Diverter Valves are primarily used to handle powders, dry solids and slurries, although some types are available that can handle liquid service. They are ideal for applications where the conveying or pumping of materials to multiple vessels or silos is needed.

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Diverter Valve Applications 

Diverter valves have the primary purpose of splitting or combining process media into one or more streams. They can be widely found in the

  • Chemical

  • Polymer

  • Refining industries 

 Broad Variety of Applications

  • To split one large process line into many smaller lines.

  • To replace several isolation valves and T-pieces in order to eliminate back flushing of dead spaces.

  • To keep one line in service whilst maintaining another.

  • Switching between filters, without downtime or pressure and flow variations.

  • To switch between control valves or pumps.

  • For high viscosity media, where dead or slow spaces lead to poor product quality.

  • To combine a process isolation and a start up dump valve in one valve body.

  • Where space does not permit larger valves or extensive piping.

  • To integrate multiple valve process functions into one valve.

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Float Valve

Types of Float Valves / Ballcock Valve

Different types of ballcock/float valves are available in market based on fitting orientation,use,working principle,size etc.

Horizontal and Vertical float Valves

  1. Vertical Float Valve

Here the float is oriented and moves in vertical direction as shown in figure. The float is directly or indirectly act on the valve seat for closing and opening the valve. The force of buoyancy is directly acting on the  seating area. The buoyancy force should be higher than the effective force due to inlet pressure for fully closing requirement of valve, So the float size is depends on the inlet pipe pressure,the more the inlet pressure higher the float size required. Vertical float valves are most suited in deep tanks/sumps where the horizontal spacing is limited mainly in industrial application like oil and chemical industry tanks for automatic shut off/filling operation.

  1. Horizontal Float Valve

Horizontal float valve is works based on the principle of force of buoyancy and principle of lever and fulcrum. As shown in figure below. Float arm acts as a lever and pivoted on body act as a fulcrum. The buoyancy force exerted on the float is transferred to the valve seating by the lever which gives more effective force on valve seating, so the more  lengthier the float arm, smaller the required float size.

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Introduction to Float Valve / Ballcock Valve

Ballcock valve is used to maintain fluid level in a storage tank or a sump. Ballcock Valves are also known as Float Valve or Ball Tap. As the name indicate it consists of a ball shaped float which sense the current level of the fluid and actuate the valve to open or close depending on the fluid level.

As shown in below figure a hollow air filled cylindrical, spherical, oblong or similarly shaped container called 'float' made metal or polymer connected to a piston operated valve using a long lever called float arm. The float am can be a flat rectangular or cylindrical in cross section. The valve used in a ballcock valve is a flow isolator valve can be of a piston operated or a diaphragm operated valve and the actuator mechanism use the float position to open and close the valve to fill the tank.

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Application of Float Valve

Water Supply

Float valves are widely used in water supply system to automatically fill the tank or sump from a main storage tank.  It can employ directly in by installing directly  inside the tank/sump or by using as remote sensing valve for the main valve.  

Household

All toilet flush tanks are employed with float valve  for filling the tank after each flush.  

Industrial

Float valves are widely used in oil,chemical,petrochemical factories for automatic filling of liquid tanks. 

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Check Valve

Types of check valves

  • Ball Check Valve

A Ball Check Valve is a Check Valve in which the closing member, the movable part to block the flow, is a spherical ball. In some ball check valves, the ball is spring-loaded to help keep it shut. For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the main seats of ball check valves are more or less conically-tapered to guide the ball into the seat and form a positive seal when stopping reverse flow.

Ball Check Valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other pumps, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials, or in some specialized cases out of artificial ruby. High pressure HPLC pumps and similar applications commonly use small inlet and outlet ball check valves with both balls and seats made of artificial ruby, for both hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, requiring replacement. Therefore, such valves are made to be replaceable, sometimes placed in a small plastic body tightly-fitted inside a metal fitting which can withstand high pressure and which is screwed into the pump head.

There are similar check valves where the disc is not a ball, but some other shape, such as a poppet energized by a spring. Ball check valves should not be confused with ball valves, which is a different type of valve in which a ball acts as a controllable rotor to stop or direct flow.

  • Diaphragm Check Valve

A Diaphragm Check Valve uses a flexing rubber diaphragm positioned to create a normally-closed valve. Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential, for the check valve to open allowing flow. Once positive pressure stops, the diaphragm automatically flexes back to its original closed position.

  • Swing Check Valve or Tilting Disc Check Valve

A Swing Check Valve or Tilting Disc Check Valve is Check Valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can come in various sizes, large check valves are often swing check valves. The flapper valve in a flush-toilet mechanism is an example of this type of valve. Tank pressure holding it closed is overcome by manual lift of the flapper. It then remains open until the tank drains and the flapper falls due to gravity. Another variation of this mechanism is the clapper valve, used in applications such firefighting and fire life safety systems. A hinged gate only remains open in the inflowing direction. The clapper valve often also has a spring that keeps the gate shut when there is no forward pressure. Another example is the backwater valve (for sanitary drainage system) that protects against flooding caused by return flow of sewage waters. Such risk occurs most often in sanitary drainage systems connected to combined sewerage systems and in rainwater drainage systems. It may be caused by intense rainfall, thaw or flood.

  • Stop-Check Valve

A Stop-Check Valve is a Check Valve with override control to stop 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 deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.

  • Lift Check Valve

A Lift-Check Valve is a Check Valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow.

  • In-Line Check Valve

An In-Line Check Valve is a Check Valve similar to the lift check valve. However, this valve generally has a spring that will 'lift' when there is pressure on the upstream side of the valve. The pressure needed on the upstream side of the valve to overcome the spring tension is called the 'cracking pressure'. When the pressure going through the valve goes below the cracking pressure, the spring will close the valve to prevent back-flow in the process.

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A Check Valve, Clack Valve, Non-Return Valve or One-Way Valve is a Valve that normally allows Fluid (Liquid or Gas) to flow through it in only one direction.

Check Valves are self-activating safety valves that permit gases and liquids to flow in only one direction. The purpose of a check valve is to prevent process flow from reversing in the system which could damage equipment or upset the process. They are classified as one-way directional valves. Check Valves are commonly found protecting pumps in liquid applications or compressors in gas systems where backflow could cause the pump or compressor to shut down. They are also applied in process systems that have varying pressures, which must be kept separate. They do not need an outside power supply to operate since they use the pressure drop created by the media flow.

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Applications of Check Valve

  • Pumps

Check Valves are often used with some types of pumps. Piston-driven and diaphragm pumps such as metering pumps and pumps for chromatography commonly use inlet and outlet ball check valves. These valves often look like small cylinders attached to the pump head on the inlet and outlet lines. Many similar pump-like mechanisms for moving volumes of fluids around use check valves such as ball check valves. The feed pumps or injectors which supply water to steam boilers are fitted with check valves to prevent back-flow.

  • Industrial processes

Valves play a large role in most industries. They are used in many parts of daily mechanical devices, including in HVAC and water systems in an office and the gasoline mechanism for an automobile. Below are a few examples of the many industries in which valves play a major role in proper operation.

Check Valves are used in many fluid systems such as those in Chemical and Power Plants, and in many other Industrial Processes.

Typical applications in the nuclear industry are feed water control systems, dump lines, make-up water, miscellaneous process systems, N2 systems, and monitoring and sampling systems. In aircraft and aerospace, check valves are used where high vibration, large temperature extremes and corrosive fluids are present. For example, spacecraft and launch vehicle propulsion propellant control for reaction control systems (RCS) and Attitude Control Systems (ACS) and aircraft hydraulic systems.

Check Valves are also often used when multiple gases are mixed into one gas stream. A check valve is installed on each of the individual gas streams to prevent mixing of the gases in the original source. For example, if a fuel and an oxidizer are to be mixed, then check valves will normally be used on both the fuel and oxidizer sources to ensure that the original gas cylinders remain pure and therefore nonflammable.

  • Domestic Use

Some types of irrigation sprinklers and drip irrigation emitters have small check valves built into them to keep the lines from draining when the system is shut off.

Check valves used in domestic heating systems to prevent vertical convection, especially in combination with solar thermal installations, also are called gravity brakeRainwater Harvesting Systems that are plumbed into the main water supply of a utility provider may be required to have one or more check values fitted to prevent contamination of the primary supply by rainwater. Hydraulic Jacks use ball check valves to build pressure on the lifting side of the jack.

  • Pipelines

This use is an essential aspect of many industries, but there are hundreds of thousands of miles of crucial pipelines that transport media from its source to the place where it will be transformed into its final product. This media could include piping for crude oil and gas, both onshore and offshore. Valves are used to optimize the pipeline operating conditions, and can be found in the upstream, midstream and downstream section of the piping. Upstream starts at the bottom of the hole in the ground and covers everything on the wellhead up to the choke. In this case, the choke is a specialized globe valve that is mounted on the wellhead to regulate the output of the well. Midstream starts at the output of the choke and ends at the fence of the final destination (usually a refinery). Downstream is everything inside the area of the destination. The most important factor to consider when selecting a valve for a pipeline application is whether the valve is piggable – that is, the inside is designed to be cleaned or inspected. 

  • Oil and Gas

The oil and gas industry is a subset of the pipelines category. Due to the high demand for oil and gas, deeper wells, longer pipelines, and lower production costs have become necessary. Along with the need for an inexpensive valve, the device must also be tougher, last longer, and perform better to meet the demands of the industry. Valve service environments and operating conditions are often extreme with high temperatures (greater than 1,500°F) and high pressure (greater than 25,000 psig) or cryogenic and very low pressure applications. Another feature important to valves used in the oil and gas industry is the capacity for remote control.

  • Food and Beverage

The food and beverage industry is a large and growing industry with an increasing need for parts and products that keep plants running smoothly .The industry’s many challenges, including safety concerns, have prompted strict material requirements for the valves used in these plants. There are two classifications for valves in the food and beverage industry: those in direct contact with food materials and those handling utility services (i.e. steam, water). For valves which come into direct contact with food, there are regulations in place (issued by such organizations as the FDA) which require that the inside of the valve be smooth enough to avoid trapping particles or bacterial accumulation. Valves made of a soft material must not absorb or hold any product going through the valve. These standards also specify that there should not be dead volume in the valve or crevices where material can be trapped to avoid decay or stagnate. Valves in the food and beverage industry do not face the high pressures or highly corrosive materials that are present in other industries.

  • Biopharm Industry

The biopharm industry is part of the larger chemical processing industry. The most important feature of valves used in this industry is their ability to be cleaned and sterilized. The chemical processing industry is responsible for processing raw materials into products. Since chemical processing often involves reactions using pressure and/or heat, and could cause toxic by-products, the media in this industry tends to be highly corrosive and abrasive. The valves need to be able to tolerate the nature of the media, as well as offer precise flow control and high leakage protection to protect against spills and cross-contamination.

  • Marine Industry

Valves play a critical role in the marine industry. As ships become larger and are used more frequently, they require the ability to generate power, treat and manage wastewater and control HVAC, as well as perform their required tasks. The size and application of the ship will determine the different types and number of valves on board. Valves are used to regulate the loading and storage of a ship’s power supply, provide water for fire-fighting capabilities, handle and processes wastewater and store any liquid cargo, among many other applications. Any valve that processes sea water must be durable, and all marine valves must be reliable due to lack of resources once out at sea.

These are just a few examples of the many industries and applications of check valves.

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Butterfly Valve

There are different kinds of butterfly valves, each adapted for different pressures and different usage. The zero offset butterfly valve, which uses the flexibility of rubber, has the lowest pressure rating. The high performance double offset butterfly valve, used in slightly higher-pressure systems, is offset from the centre line of the disc seat and body seal (offset one), and the centre line of the bore (offset two). This creates a cam action during operation to lift the seat out of the seal resulting in less friction than is created in the zero offset design and decreases its tendency to wear. The valve best suited for high-pressure systems is the triple offset butterfly valve. In this valve the disc seat contact axis is offset, which acts to virtually eliminate sliding contact between disc and seat. In the case of triple offset valves the seat is made of metal so that it can be machined such as to achieve a bubble tight shut-off when in contact with the disc.

Types of Butterfly Valves

  1. Concentric butterfly valves - This type of valve has a resilient rubber seat with a metal disc.

  2. Doubly-eccentric butterfly valves (high-performance butterfly valves or double-offset butterfly valves) - Different type of materials is used for seat and disc.

  3. Triply-eccentric butterfly valves (triple-offset butterfly valves) - The seats are either laminated or solid metal seat design.

002-wafer-style-butterfly-valve

A butterfly valve is a valve which can be used for isolating or regulating flow. The closing mechanism takes the form of a disk. Operation is similar to that of a ball valve, which allows for quick shut off. Butterfly valves are generally favored because they are lower in cost to other valve designs as well as being lighter in weight, meaning less support is required. The disc is positioned in the center of the pipe, passing through the disc is a rod connected to an actuator on the outside of the valve. Rotating the actuator turns the disc either parallel or perpendicular to the flow. Unlike a ball valve, the disc is always present within the flow, therefore a pressure drop is always induced in the flow, regardless of valve position.

A butterfly valve is from a family of valves called quarter-turn valves. In operation, the valve is fully open or closed when the disc is rotated a quarter turn. The "butterfly" is a metal disc mounted on a rod. When the valve is closed, the disc is turned so that it completely blocks off the passageway. When the valve is fully open, the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the fluid. The valve may also be opened incrementally to throttle flow.

 

005-application-of-butterfly-valve

Application of Butterfly Valves

In the pharmaceutical, chemical and food industry a butterfly valve is used to interrupt product flow (solid, liquid, gas) within the process. The valves used in these industries are usually manufactured according cGMP guidelines (current good manufacturing practise).

Butterfly valves can be used in many applications because they can be used with many different media types including water applications, corrosive materials and some slurries. Typical applications include:

 

  • Cooling water, air, gases, fire protection, etc.

  • Slurry and similar services

  • Vacuum service

  • High-pressure and high-temperature water and steam services.

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