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    Control Valves Types

    a. According to the Function of the Control Valves

    A pneumatic on/off valve is used for tight closing applications for liquids, gases, and vapors. It has standard options such as temperature extensions and metal bellows seals.

    As this control valve is designed according to the modular assembly principle, so it can be assembled with a pneumatic actuator and an option with a handwheel, it also can be equipped with other accessories, such as limit switches, solenoid valve, and so on.

    Features & Benefits

    • Compact designed Pneumatic On/OFF Valve
    • Easy addition of handwheel, metal bellows seal, and thermal extensions
    • Bonnet and body made of the same material for process compatibility
    • Class VI shut-off with PTFE insert in the plug

    hsc pneumatic single seated cage type control valve

    Modulating type control valves include single-seated control valves, double-seated control valves, angle type control valves, cage guided control valves, and so on.

    For example, cage guided type balanced trim, movement balanced ring, fission labyrinth type standard cage, optional movement seal ring, high strength structure. The 510D series is the most pointed control valve in the high differential pressure operating mode, has used the labyrinth type valve cage, has the characteristic which multistage falls pressure, the multilayered labyrinth gasket type valve can reduce the fluid noise and eliminate cavitation as well as the multi-hole cage valve. Moreover, reduces the volume greatly, the trim in the valve is interchangeable between the HCB series control valve with the HSC series Cage Guided control valve.

    pneumatic control globe valves

    A self-acting control valve is also known as a self-operated pressure regulator, which doesn’t need any auxiliary power to drive the valve, the self-acting control valve through the medium energy to operate the valve itself, that’s why it is called self-acting or self-operated. A self-operated control valve can realize the adjustment of temperature, pressure, differential pressure, flow rate, and other parameters. It has the characteristics of simple structure, low price, reliable action, and so on. It is suitable for occasions where flow rate changes are small, adjustment accuracy is not high, or instrument air/power supply is difficult.

    图片6

    b. According to the Nominal Pressure of the Control Valves

    Nominal Pressure PN of Control Valves Less Than 1.6MPa

    Nominal Pressure PN of Control Valves Range 2.5 to 6.4MPa

    Nominal Pressure PN of Control Valves Range 10.0 to 80.0MPa

    Pneumatic top guided single-seated angle control Valve applied with an unbalanced plug, this top guided single seated angle control valve requires a large actuator output force. The size is reduced by incorporating a fine designed multi-spring diaphragm actuator. This series is a good application for slurry polymer crystallization and high-temperature fluid as the pressure balanced structure is not used here.

    510D Model is adopted cage guided type balanced trim, movement balanced ring, fission labyrinth type standard cage, optional movement seal ring, high strength structure. The 510D series is the most pointed control valve in the high differential pressure operating mode, has used the labyrinth type valve cage, has the characteristic which multistage falls pressure, the multilayered labyrinth gasket type valve can reduce the fluid noise and eliminate cavitation as well as the multi-hole cage valve. Moreover, reduces the volume greatly, the trim in the valve is interchangeable between the HCB series control valve with the HSC series Cage Guided control valve.

     

    c. According to the Different Actuator Type For Control Valves

    manual control valves manufacturer
    manual control valves supplier
    electric globe type control valves
    electric globe type control valves
    control valves for boiler6
    control valves for boiler6

    d. According to the Closure Member’s Movement

    In this type, the flow of the fluid is modified by the closure member in rotary motion. Rotary motion valves are of three types.

    • Ball Type – As the name suggests, the shape of the valve is like a ball with a container for fluid flow. Right at the opening, this valve enables the flow and after being rotating at 90° it stops the flow. Ball valve has good resistance towards high temperature & high pressure. The advantage of the ball valve is easy to maintain and has low torque. On the other hand, it also has the disadvantage of causing corrosion when the fluid gets trapped inside the valve mainly during a closed position.
    • Butterfly Type – Butterfly valve has a disc rotating at 90˚ inside the pipe. The disc allows the stem to pass through it and is supported by both ends. Similar to the ball valve, the butterfly valve also stops with a right-angle rotation. The butterfly valve has the capacity of controlling large flow and low-pressure applications. It is affordable and has a quick opening. It has only one disadvantage of loose shut-off.

    high performace butterfly valve manufacturer in china3

    high performace butterfly valve manufacturer in china1

    • Plug Type – The plug valve is available in both cylindrical and tapered shapes. At the time of opening of this valve, both inlet and outlet ends of this valve, are connected to give a flow line. This valve is suitable for both chemical and petrochemical industries. The plug valve has advantages like less maintenance, fewer requirements of headroom, and quick opens. It has a low-pressure drop and doesn’t provide loose shut-off like a butterfly valve. The plug valve also has disadvantages like not affordable and is not useful for throttling action.

    eccentric plug valve5

    • Gate Type –In high temperatures, the gate valve is used for on/off applications. This is also recommended for non-throttling services because of its fully closed or fully open designs. It has a sliding gate to control the flow. It works well at the time of straight-line flow of liquid with minimum restrictions. Based on shape, the gate valve is further divided into two categories: Parallel and wedge.
      The gate valve starts working when the stem is rotated either clockwise to close motion or clockwise to open motion. As you move the stem, the gate valve moves up and down. The advantage of a gate valve is it comes with a tight sealing. Gate valve also has the disadvantage of requiring more actuating force.
    • Globe Type – Due to the globular shape, this valve is named a globe valve. Its closure member is a plug with a button, located right at the center. When the plug is raised, the globe valve allows the fluid flow. Globe valve mainly has 3 body designs as Z, Y, and angle body. The advantage of the globe valve is it has better throttling characteristics than other valves. It also has the disadvantage of having a high-pressure drop.
    • Diaphragm Valve –The diaphragm valve has a compressor that is connected to a flexing diaphragm. This diaphragm is lifted at the time of opening of this valve and allows the fluid flow. When the valve is closed, it closes the path tightly. The diaphragm valve works at low temperature and low pressure and is highly suitable for corrosive liquids. The advantage of the diaphragm valve is it is easy to maintain and has a simple construction. It also has disadvantages like it can’t be used in high temperatures and high pressure.
    • Pinch valve – A pinch valve is more cost-effective than other valves. This valve is used for slurries or liquids having minimal solid particles. It is similar to a diaphragm valve but uses flexible elements like rubber to turn off the fluid flow. To actuate the pinch valve, hydraulic pressure is placed on the elastomer sleeve. The pinch valve doesn’t have any internal obstructions and hence it has a low-pressure drop. This is a good advantage of the pinch valve.

    What is terminology or symbols in Control System in the Process Automation?

    control valves for process automation

    Normally the industrial process is by open-loop control or closed-loop control to maintain the desired data such as flow capacity, pressure, or temperature.

    Open-Loop and Closed-Loop Control Systems

    Generally, the open-loop control system that controls action only depends on the input signal without its output response.

    The closed-loop control system that controls action depends on both of input signal and a feedback signal from the valve controllers. 

    open loop control system
    open loop control system

    Operator controls the process variable p2 via remote adjuster 

    closed loop control system
    closed loop control system

     Operator controls the process variable p2 an a closed-loop

    Controlling system: Controller and actuator

    Controlled system: Final control element, pump, pipeline, heating system, etc.

    Input signal: It is the signal from the control room/operator controls to the valve positioner.

    Output signal: It is the signal from the valve positioner then feedback to the control system.

    Pneumatic globe type control valves: Globe valve, actuator, valve positioner, air filter regulator.

    Actuator: It is the device to provides the power to activate the valves.

    Steam Control Valves with Pneumatic Actuators

    pneumatic control valves

    Steam control valves with pneumatic actuators are widely used for industrial processes, such as sugar mills, power plants, chemical industry, oil, and gas.

    Usually, it is assembly with E/P or P/P valve positioner to receive an input signal from the controller room, 4-20mA or 3-15psi.

    pneumatic globe type control valves thintkank
    pneumatic globe type control valves manufacturer

    Description

    The multi-spring membrane pneumatic actuators of P/R type are applied for control operation of control valves and other positioning elements in automatic industrial systems. There are two following design options of the actuator:
    – Direct action (air – advances the stem)
    – Reverse action (air – retracts the stem)

    Features

    • Completely reversible action, option to change spring range w/o extra parts.
    • Strong structure of cast yoke.
    • Wide range of the available forces.
    • A linear relationship between rod displacement and control pressure as a result of using membranes with constant active area.
    • Various ranges of spring pressures due to the changeability of spring number and /or dislocation of distance fencers.
    • The capability of the actuator to incorporate side-mounted handwheel, pneumatic or electro-pneumatic positioners, limit switches, air sets, three-way pneumatic solenoid valves, lockup valves, position transducers.
    • The high strength of diaphragms, springs, and packings.
    • Compact size and lightweight.
    multi spring diaphragm actuator
    multi-spring diaphragm actuator

    ( a) Direct-acting( PZMA)
    1. Up diaphragm castings 2. Diaphragm
    3. Diaphragm plate 4. Spring
    5. Down diaphragm castings 6. Actuator stem
    7. Yoke 8. Adjust nut 9. Travel indicator

    multi spring diaphragm actuator 2
    multi-spring diaphragm actuator 2

    ( b) Reverse-acting ( PZMB)
    1. Up diaphragm castings 2. Diaphragm
    3. Diaphragm plate 4. Spring
    5. Down diaphragm castings 6. Actuator stem
    7. Yoke 8. Adjust nut 9. Travel indicator

     

    Model TT-667 actuator is a reverse-acting, spring-opposed diaphragm actuator. The actuator positions the valve plug in response to varying pneumatic loading pressure on the actuator diaphragm.

    Description
    Our Model TT-667 diaphragm actuator with a single spring is 100% to replace Fisher 667 actuators, which are designed to ensure stable on/off or throttling operation of the control valve. These spring-balanced membrane actuators respond to the pneumatic output signal of the controller or valve positioner to determine the position of the valve plug. 667 diaphragm actuator is a reverse-acting.

    Specifications:

    • Acting type: spring return, linear
    • Control type: on/off, throttling
    • Working temperature: low temperature, standard temperature, high temperature
    • Power supply: pneumatic, manual
    • Valve type: angle, globe
    • Sizes for 667 models: 667-30, 667-34, 667-40, 667-45, 667-46, 667-50, 667-60, 667-70
    • The diaphragm size of the actuator: 30, 34-40, 45-50, 46-60, 70
    fisher type control valves
    fisher type control valves
    control valves for boiler6

    It could be a single-seated, double-seated, cage-guided, top-guided globe type trim design for the industrial engineering process. The control valve body assembly with a pneumatic actuator to modulate or shut off downstream pressure, flow rate, or temperature.

    control valves for boiler7
    control valves for boiler7

    Three ways control valves are service for diverting or mixing service. The pneumatic actuator is designed as a rubber diaphragm with multi-springs, or piston/cylinder type pneumatic actuator with single-acting or double-acting.

    the principle of action 3 way control valves direct action mixing type
    the principle of action 3 way control valves direct action mixing type
    three way control valve dynamic demonstration
    three way control valve dynamic demonstration

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