Showing posts with label fluid handling. Show all posts
Showing posts with label fluid handling. Show all posts

Tuesday, August 30, 2016

Applications For Metal Seated Ball Valve

metal seated ball valve with handle and flange connections
Metal Seated Ball Valve
Crane - Krombach
Fluid process control employs valves of various types to start, stop, throttle, or divert flow of a fluid. Ball valves are a common selection for process application when their inherent advantages provide the greatest benefit.
  • Leak-proof service
  • Well suited for processes requiring only full flow or no flow operation.
  • Rapid open and close action, requiring only 90 degrees of rotation from fully open to fully closed.
  • Comparatively light weight and compact size.
  • Wide range of construction material options for body, ball, and seals make them suitable for many applications.
  • Require only moderate force to control valve position.
  • Flow path opening in the ball will often be “full port”, providing same cross section as the connected pipe and adding very little restriction or pressure drop to the flow.
  • Low maintenance, with no lubrication required.
There are numerous ball valve variants that provide modified features and performance, but let's focus on what is generally considered severe service applications.

Severe service, while not currently defined by an international standard, generally can be characterized by one or more operating conditions that put great levels of stress or wear on valves.
  • 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
  • Corrosive media
Some of these conditions will greatly impact the valve seat. Many valves are provided with thermoplastic seats that, while providing suitable performance throughout a wide range of media conditions, will deteriorate quickly under conditions prevailing in severe service. An alternative to the soft thermoplastic seats is a metal seat design. 
  • Greater temperature tolerance
  • Self cleaning seat
  • Improved resistance to effects of particulate laden media or slurries
  • Corrosion resistance, enhanced by special coatings applied to metal construction
The document below provides an in depth view of a metal seated ball valve. Operating conditions, specifications, and illustrations (including my favorite, the cutaway view) are provided. Share your fluid control requirements with product and application specialists, combining your process expertise with their product application knowledge to develop effective solutions.


Monday, August 22, 2016

High Performance Non-Slam Check Valve

high performance dual plate check valve
Crane Duo-Chek dual plate check valve
Check valves are ubiquitous throughout fluid processing operations. These simple devices permit fluid flow in one direction only. While there are numerous design variants available in the marketplace, operation is very similar in all check valves. Fluid pressure and movement in the desired direction moves a plate, plug, ball, or other obstruction to a position that allows flow to pass. The plate or other obstruction has a design countervailing force applied to it by a spring, gravity, or some other means that will move the trim to the closed position. When pressure drop across the valve decreases below the design level, the trim will close. Fluid pressure exerted on the outlet side of the valve will maintain a closed position in the valve. In this manner, a check valve allows fluid to pass in one direction, but not in the reverse.

Beneficial features of a check valve would include some or all of the following:

  • Lightweight and compact design
  • Tight shutoff that meets any applicable standards
  • Low pressure drop when open
  • Operation that minimizes seal wear
  • Installation simplicity and flexibility
  • Easy to insulate
  • Low maintenance requirements
  • No slamming to the closed position
  • No valve chatter
  • Available in numerous configurations to meet wide range of applications
Share your fluid process control challenges with a product application specialist. Combine your process knowledge with their product application expertise for effective solutions.




Monday, September 14, 2015

No Compressed Air? Use Water to Power Your Valve Actuator.

Hytork XLW Water Powered Valve Actuator
XLW Water Powered Valve Actuator
Courtesy Hytork
Air is everywhere, but very little of it is compressed for our use in powering a valve actuator. Sometimes, possibly at sites located remotely, a reliable source of compressed air is unavailable for process control valve actuation. Installing an air compressor at the site may be an option, but one with impact on the reliability of the installation deemed undesirable. One possible solution is a water powered valve actuator. With mains water available, pressurized within the range of 60 to 100 psi (4-7 bar), actuator power can be derived and valve operation successfully achieved.

Water always presents its own set of special considerations, not the least of which is that it tends to corrode most metals used in construction of actuator parts over time. Of additional concern are the particulates present in water systems which can cause premature deterioration of seals and scoring of cylinders in the actuator. Directional control solenoid valves will also function more reliably with a water supply free of larger particulates. While this is a concern, the solution is simply to place an inexpensive filter upstream of the devices, eliminating the contaminates from the water supply.

While it is possible to employ some "standard" actuators in a water powered setting, there are special adaptations that can be applied to common actuator design to better suit the use of water power. One manufacturer, Hytork, has done just that with their XLW Series of water operated actuators. The XLW Series is a water powered adaptation of the company's successful XL Series actuators. Special coatings are applied to critical parts to provide necessary protection for water applications. There are other differences between the compressed air and water versions of the actuator, detailed in the installation and operating instruction manual shown below. The manual is short enough to be read in a couple minutes (really, just a couple minutes) and provides useful and illustrative information about actuator construction, operating characteristics, and maintenance requirements.

Contact a valve application specialist for more information, or to discuss any of your fluid control application needs.


Monday, June 22, 2015

Selecting the Right Valve Type - Gate Valves

There are many types of valves available for industrial fluid handling and process control applications. Specifying the proper valve type for an application can be made easier with some basic knowledge about the application strengths and weaknesses of the various valve types.

gate valve cutaway view
Gate Valve Cutaway View
Courtesy DHV Industries
Gate valves open and close by changing the position of a rectangular or round wedge (the gate) in the fluid flow path. The sealing surfaces are arranged in a planar fashion and the gate, which is commonly either flat or wedge shaped, slides along the sealing surface from the open to closed position. Because of the cross-sectional shape of pipes, which is often mimicked in the valve body, the size of the opening created as the gate valve opens and closes does not change at the same rate as the percentage of total available movement of the gate. This non-linear aspect of valve operation can make a gate valve less suitable for an application where flow rate must be accurately controlled across the range from fully open to fully closed. Complicating throttling operations further is the possibility of the gate vibrating when partially open, due to the fluid flow around the gate assembly. Unless specifically designed for throttling, gate valves are generally best suited for applications requiring either full flow or no flow. Because of its operating nature and construction, a gate valve may prove to be the appropriate selection, based upon the type of media or fluid which is being controlled.

In addition to specifying the manner in which the valve will be connected within the piping system, consideration should be given to construction of the valve body. If it may be necessary to inspect, service, or clean the valve interior, look for a bonnet connection that will permit suitable access to the valve interior.

Once you have decided that a gate valve will be the most suitable type for your application, there are many other considerations in valve selection. Draw on the experience and knowledge of coworkers, maintenance technicians, and valve sales engineers to help specify a valve assembly that meets the needs of all project stakeholders.