CONTROL VALVE ACCESSORIES

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What are control valves?

A control valve is the most commonly used to regulate fluid flow in the process. Control valves are the element controlling the pressure and the flow inside a system or within a process. These mechanical devices are there to control liquids, gasses, vapours, slurry, and so on. Some of the control valves are manual but automatic control valves are also available when the condition and environmental condition is suitable for such units.

To understand the different applications of compressed air and how valves are used, one must first have knowledge of the kinds and types of valves used by industries.

What are different control valve parts?

Depending on the control valve characteristics and its design, some parts differ within the control valve, but the rest is pretty much the same. Control valve positioner, trim, body, etc. are all there within control valves as their basic components. Examples of different control valve types are Gate, Globe, Check, Plug, diaphragm, Ball, Butterfly, pressure relief, etc. Each type has multiple models and each model has different parts with different features and functionalities.

The main goals of different control valve parts:

1. Controlling the flow direction

2. Relieving the system from specific pressures

3. Increasing or decrease the flow

4. Turning the flow on or off

5. Regulating the flow or process pressure

Control Valve Accessories

The following list shows the most commonly used accessories with the control valve, as per the requirements.

1. Pneumatic Positioners

2. I/P Transducers

3. Volume Boosters

4. Position Transmitters

5. Limit Switches

6. Solenoid Valves

7. Air Lock relay

8. Handwheel

I/P Transducer-

A current to pressure uses a converter module that converts a 4 to 20 mA current input to a proportional 3 to 15 psi pressure output.

In some applications, where a high level of positioning accuracy by a positioner is not required. In these applications, an electro-pneumatic (I/P) transducer only can be used.

Position Transmitter-

The purpose of a position transmitter is to provide independent, separate valve position feedback to the control system. Position feedback of the control valve often becomes necessary as it is used for process monitoring, troubleshooting, or startup/shutdown verification from the control room by an operator. The position transmitter is mounted directly to the valve yoke and measures the position of the valve stem or shaft.

Limit Switches

The purpose of a Limit Switch is to provide a discrete open or discrete close input signal to the control system when the valve reaches a specific position within its range of travel.

Limit switches, which are mounted on the control valve and on the yoke are also used for process monitoring, troubleshooting, or startup/shutdown verification from the control room by an operator.

These switches will only provide specific valve position feedback. These can be mounted on the control valve to get additional feedback signals to the DCS or PLC systems as per our requirement.

Valve Positioner:

Valve positioners are devices used to put a valve in the correct position by increasing or decreasing the air load pressure on the actuator. Instead of the process controller sending a signal directly to the actuator to move the valve, a valve positioner senses the exact position of the valve and communicates to the actuator to move the valve.

Valve positioners are usually mounted on the yolk or top casing of a pneumatic actuator (for linear control valves), or near the end of the shaft (for rotary control valves). For either set-up, the positioner is connected mechanically to the valve stem or valve shaft. This allows for the valve&#;s position to be compared with the position requested by the controller.

Advantages of Valve Positioner :

1. Minimizing the effect of friction, hysteresis, and dead band on the valve stem.
2. Enables signal range change.
3. Allows control valve signal reversal: A positioner can operate in either direct or reverse acting mode. In direct acting mode, an increase in control signal pressure causes an increase in positioner output air pressure. In reverse acting mode, an increase in control valve signal pressure causes a decrease in positioner output air pressure.
4. A positioner Increases the speed of response of the actuator.

5. Allows valve flow characteristics to be changed.

6. Allows split range operation. In a split range control loop, one controller output is used to drive two control valves.

Blog by,

N ikita Sawant, ICE-B, Roll No.33,

PRN- , Group 4, Batch 2.

Some accessories make you look fashionable. Others help your rotary airlock valves work safely, smoothly and efficiently.

Would rotary valve accessories impress your friends at a fancy dinner party? Hey, you never know &#; but the important thing is that they benefit your conveying process in various ways. Here&#;s an overview of the options we provide at ACS.

For jam prevention: Shear Protectors

Granular materials such as plastic pellets, plastic flakes, wood pellets, and other large or bulky materials are prone to rotor jamming. That&#;s where different types of shear protectors come in. As material enters the valve&#;s inlet port and fills the rotor pockets, the shear protector&#;s wiper blade sweeps any overflow into the next pocket. This stops materials from getting stuck in the clearances between the rotor and housing.

Shear protectors come in different shapes and styles to fit your conveying line: there&#;s a standard spool style, a vented spool style that releases pressured air, and a half-moon style for systems with height restrictions. All three come in square or round options.

For wood dust: Inlet Shunt with Tip Cleaner

Similar to a shear protector, this one is highly recommended if you&#;re conveying wood dust. The inlet shunt&#;s shape restricts the valve inlet slightly, and its rubber tip cleaner wipes the rotor tips as they spin, helping to prevent material jamming.

For safety: Discharge Finger Guard

Keep those fingers safe! With options for round and square inlets, this mandatory safety feature protects workers from rotary valves with an open or exposed discharge area. It&#;s fully CSA and OSHA compliant.

For connectivity: Discharge Blow-Through Adapter

A discharge blow-through adapter connects the discharge of your rotary valve to a pressure conveying system. In other words, it takes material from the valve&#;s outlet port and blows it wherever it needs to go in your plant. We often recommend pairing this with a vent box, as you&#;ll see below.

For air release: Vent Box

A useful option for pneumatic conveying lines, the vent box usually sits above the valve. As pressurized air comes up from the line, it leaks into the empty rotor pockets on their way back up the valve. The vent box relieves this air to keep your process going smoothly.

For gravity flow: Maintenance Slide Gate

With different settings to help you control the flow of material, the maintenance slide gate is designed for gravity-flow applications. The air-operated version comes with variable slide gate actuation so you can keep it partially open, fully open or fully closed. It also comes with options for electric slide gate actuation, pneumatic operation or manual operation.

Bonus: Kits for material aeration, safety and speed monitoring

That sums up the main accessories, but there are so many more options to outfit your valves that we can&#;t fit them all in one blog. You could also consider kits: there&#;s one to monitor shaft speed, one to cover exposed areas of the shaft, and a few that blow compressed air into areas of the valve that may be prone to material buildup. Feel free to ask us about them!

Which accessories are right for your valve?

By now, you&#;ve probably realized that your choice of accessories depends on your application. The right ones help to keep workers safe, extend maintenance cycles and boost conveying efficiency. ACS Valves is here to help with that decision: when you work with us, we can recommend the best accessories to complement your process. Give us a call to get started.

5. Limit Switches

6. Solenoid Valves

7. Air Lock relay

8. Handwheel

I/P Transducer-

A current to pressure uses a converter module that converts a 4 to 20 mA current input to a proportional 3 to 15 psi pressure output.

In some applications, where a high level of positioning accuracy by a positioner is not required. In these applications, an electro-pneumatic (I/P) transducer only can be used.

Position Transmitter-

The purpose of a position transmitter is to provide independent, separate valve position feedback to the control system. Position feedback of the control valve often becomes necessary as it is used for process monitoring, troubleshooting, or startup/shutdown verification from the control room by an operator. The position transmitter is mounted directly to the valve yoke and measures the position of the valve stem or shaft.

Limit Switches

The purpose of a Limit Switch is to provide a discrete open or discrete close input signal to the control system when the valve reaches a specific position within its range of travel.

Limit switches, which are mounted on the control valve and on the yoke are also used for process monitoring, troubleshooting, or startup/shutdown verification from the control room by an operator.

These switches will only provide specific valve position feedback. These can be mounted on the control valve to get additional feedback signals to the DCS or PLC systems as per our requirement.

Valve Positioner:

Valve positioners are devices used to put a valve in the correct position by increasing or decreasing the air load pressure on the actuator. Instead of the process controller sending a signal directly to the actuator to move the valve, a valve positioner senses the exact position of the valve and communicates to the actuator to move the valve.

Valve positioners are usually mounted on the yolk or top casing of a pneumatic actuator (for linear control valves), or near the end of the shaft (for rotary control valves). For either set-up, the positioner is connected mechanically to the valve stem or valve shaft. This allows for the valve&#;s position to be compared with the position requested by the controller.

Advantages of Valve Positioner :

1. Minimizing the effect of friction, hysteresis, and dead band on the valve stem.
2. Enables signal range change.
3. Allows control valve signal reversal: A positioner can operate in either direct or reverse acting mode. In direct acting mode, an increase in control signal pressure causes an increase in positioner output air pressure. In reverse acting mode, an increase in control valve signal pressure causes a decrease in positioner output air pressure.
4. A positioner Increases the speed of response of the actuator.

5. Allows valve flow characteristics to be changed.

6. Allows split range operation. In a split range control loop, one controller output is used to drive two control valves.

Blog by,

N ikita Sawant, ICE-B, Roll No.33,

PRN- , Group 4, Batch 2.

Some accessories make you look fashionable. Others help your rotary airlock valves work safely, smoothly and efficiently.

Would rotary valve accessories impress your friends at a fancy dinner party? Hey, you never know &#; but the important thing is that they benefit your conveying process in various ways. Here&#;s an overview of the options we provide at ACS.

For jam prevention: Shear Protectors

Granular materials such as plastic pellets, plastic flakes, wood pellets, and other large or bulky materials are prone to rotor jamming. That&#;s where different types of shear protectors come in. As material enters the valve&#;s inlet port and fills the rotor pockets, the shear protector&#;s wiper blade sweeps any overflow into the next pocket. This stops materials from getting stuck in the clearances between the rotor and housing.

Shear protectors come in different shapes and styles to fit your conveying line: there&#;s a standard spool style, a vented spool style that releases pressured air, and a half-moon style for systems with height restrictions. All three come in square or round options.

For wood dust: Inlet Shunt with Tip Cleaner

Similar to a shear protector, this one is highly recommended if you&#;re conveying wood dust. The inlet shunt&#;s shape restricts the valve inlet slightly, and its rubber tip cleaner wipes the rotor tips as they spin, helping to prevent material jamming.

For safety: Discharge Finger Guard

Keep those fingers safe! With options for round and square inlets, this mandatory safety feature protects workers from rotary valves with an open or exposed discharge area. It&#;s fully CSA and OSHA compliant.

For connectivity: Discharge Blow-Through Adapter

A discharge blow-through adapter connects the discharge of your rotary valve to a pressure conveying system. In other words, it takes material from the valve&#;s outlet port and blows it wherever it needs to go in your plant. We often recommend pairing this with a vent box, as you&#;ll see below.

For air release: Vent Box

A useful option for pneumatic conveying lines, the vent box usually sits above the valve. As pressurized air comes up from the line, it leaks into the empty rotor pockets on their way back up the valve. The vent box relieves this air to keep your process going smoothly.

For gravity flow: Maintenance Slide Gate

With different settings to help you control the flow of material, the maintenance slide gate is designed for gravity-flow applications. The air-operated version comes with variable slide gate actuation so you can keep it partially open, fully open or fully closed. It also comes with options for electric slide gate actuation, pneumatic operation or manual operation.

Bonus: Kits for material aeration, safety and speed monitoring

That sums up the main accessories, but there are so many more options to outfit your valves that we can&#;t fit them all in one blog. You could also consider kits: there&#;s one to monitor shaft speed, one to cover exposed areas of the shaft, and a few that blow compressed air into areas of the valve that may be prone to material buildup. Feel free to ask us about them!

Which accessories are right for your valve?

By now, you&#;ve probably realized that your choice of accessories depends on your application. The right ones help to keep workers safe, extend maintenance cycles and boost conveying efficiency. ACS Valves is here to help with that decision: when you work with us, we can recommend the best accessories to complement your process. Give us a call to get started.

If you are looking for more details, kindly visit Automation Components.