Showing posts with label valve. Show all posts
Showing posts with label valve. Show all posts

Rotary Vane Actuators for Quarter Turn Valve Automation

rotary vane actuator open for inside view
The inside of a rotary vane actuator
Image courtesy of Kinetrol
A rotary vane actuator is part of an automated valve assembly. Its role is to change the position of the valve trim, converting the motive force of fluid pressure in the actuator into torque at the valve stem.

Quarter turn valves are widely used in industrial fluid processes. Their application is primarily for operations requiring fully open or fully closed valve trim positions, although some do provide modulating service. A rotation of the valve stem through a 90 degree arc will reposition quarter turn valves between open and closed positions. A rotary vane actuator is well suited for driving this type of valve, with its own 90 degree arc of movement.

A rotary vane actuator is specific for application to quarter turn valves. A pressure tight housing contains a movable vane which is sealed to the sides of the pressure chamber by means of a low friction gasket. Inlets into the chamber on opposing sides of the vane allow a controller to produce a pressure differential across the vane. The vane will move, responding to the pressure differential, in either direction. A shaft is connected to the vane and the vane acts like a lever to rotate the shaft as the vane is moved by fluid pressure. The torque produced by the actuator assembly is primarily dependent upon the applied fluid pressure.

Hydraulic rotary vane actuators have the ability to handle large amounts of fluid and dynamic motions, exhibiting also qualities of durability and compactness. Pneumatic vane actuators use plant air pressure as the motive force. Both types generally have few moving parts and require little regular maintenance. A variety of typical automation accessories and options are available to customize a unit for a particular application.

Analynk Wireless manufactures wireless connectivity solutions for industrial applications and process control. Making cable free connections among process control equipment and instruments, across the room, across the property, across the globe.

Severe Service Valves

steel industrial piping and valves
Careful matching of process valves to intended use
results in better and longer service
Industrial process control applications can be associated with some very stringent and challenging performance requirements for the physical equipment and components that are part of the process chain. In fluid based operations, the control and shutoff valves can be a significant impact point of extreme fluid conditions, requiring careful design and selection consideration to assure proper performance and safety levels are predictably maintained.

Industrial valves that are intended for application at the extremes are generally referred to as severe service valves. While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define a severe service valve. There is, however, some movement toward the development of severe service standards in some industry segments.

So, how do you know when to focus valve selection activities on severe service valves, as opposed to general purpose valves? There are a number of basic criteria that might point you in that direction:
  • Very extreme media or environmental temperature
  • High pressure drop operation that may cause cavitation
  • Rapid and extreme changes to inlet pressure
  • Certain types or amounts of solids contained in the fluid
  • High number of mechanical operations
  • Thermal cycling
Certainly, any of these criteria might be found in an application serviceable by a general purpose valve, but their presence should be an indicator that a closer assessment of the fluid conditions and commensurate valve requirements is in order. The key element for a process stakeholder is to recognize when conditions are in evidence that might overrun the capabilities of a general purpose valve, leading to premature failure in control performance or catastrophic failure that produces an unsafe condition. Once the possibility of a severe service condition is identified, a careful analysis of the possible operating conditions will reveal the performance requirements for the valve.

There are numerous manufacturers of severe service valves, each seeming to concentrate on a particular niche. You can always get more information, or discuss your special requirements, with a valve specialist. They have access to technical resources that can help with selecting the right valve configuration to meet your severe service applications.

Analynk Wireless designs and manufactures equipment that establishes wireless connections among process measurement and control devices.

Specialty Valve for Transmitter Isolation

specialty transmitter isolation valve
Transmitter Isolation Valve
Courtesy PBM Valve Solutions
Fluid process control applications frequently employ tanks and vessels as part of the processing chain or for storage and holding. Level transmitters can be installed on the tank to provide indication of liquid level. While there are numerous combinations of fittings and valves that could be used to mount and connect the transmitter to the tank, one manufacturer, PBM Valve Solutions, has designed a specialized valve intended to mate a transmitter to a tank fitting with great advantage.

The specialized transmitter isolation valve minimizes dead space to prevent media residue buildup. It can be configured to accommodate CIP and drainage without process interruption. Calibration ports and industry standard mountings allow for broad application throughout the fluid process control industries.

Establishing a connection between the transmitter and its associated monitoring or control equipment is a specialty of Analynk Wireless. Analynk provides end to end solutions for delivering transmitter signals using wireless communications that can span across the room or around the globe. Reach out to Analynk for effective and easy to implement wireless solutions.

Flow Control of Slurries and Liquids With Entrained and Suspended Solids

rubber lined pinch valve for industrial application
Cutaway view of  manually
operated pinch valve
Courtesy General Rubber
Industrial process control can involve the manufacture, storage, or transport of almost any imaginable fluid. Media can range from water to concrete, hydrogen gas to steam, and anything in between or outside of those boundaries. Valves are a favored control device for regulating fluid flow and they are available in uncountable varieties, each with particular aspects making them more or less suitable for a particular media or application.

Most industrial valves consist of a body, a stem, and some form of flow obstruction which is located within the media flow path. Operation of the stem repositions the obstruction to allow or block the flow. All of these valve types have a defined sealing surface where the obstruction contacts the body. They also have additional seals where the stem penetrates the body. These design features, while providing certain functions and application advantages, also add to the operational complexity and parts count for the valve.

There is a valve type with a simple operating principle that provides superior performance when the application involves certain media characteristics. It is called a pinch valve, and here is where it excels.
  • Resistance to abrasion and corrosion from slurries or fluids containing suspended solids and the ability to provide tight shutoff around particulates
  • Media and environmental temperature range -40 deg F to +300 deg F
  • Low to moderate operating pressure
  • Flow regulating capability and tight shutoff
  • Non clogging
  • Straight through full bore design with minimal flow resistance
  • Isolation of the valve body and workings from the media
  • Low parts count, low maintenance, easy repair/replacement
A pinch valve consists of a sleeve, through which fluid flows, and a means to compress or "pinch" the sleeve to reduce the open area inside the sleeve. The sleeves are most often fabricated from elastomers with various types of fiber reinforcement. Closure is commonly achieved through movement of one or two bars to squeeze the sleeve, providing throttling or positive closure. The flexibility of the sleeve material allows for tight shutoff, even with fluids containing suspended solids. The valves can be coupled with electric or pneumatic actuators and are available with industry standard connections. One valve variant has a body that can be pressurized to close the sleeve, without the need for a separate actuator. Pinch valves are available with and without an enclosing body.

You should be familiar with the capabilities and forms of this unique valve type. When confronted with certain application challenges, a pinch valve can be a superior solution.

Analynk is committed to excellence in process control, providing wireless communications for process signals, as well as explosion proof enclosures for wireless access points.