Friday, February 23, 2018

Industrial Diaphragm Valves

sectional drawing weir type diaphragm valve with pneumatic actuator
Section drawing of diaphragm valve, weir type,
with pneumatic actuator.
Image courtesy Gemu Valves, Inc.
Diaphragm valves are named for the means employed in their design to restrict the path of fluid flow through the valve. Most valve designs employ a rigid solid shape which is repositioned in the fluid path to regulate flow. Diaphragm valves are somewhat unique in their use of a flexible material that is deformed by a moving part connected to the valve operating mechanism. The diaphragm acts as the flow restrictor and seat. It also isolates the valve bonnet and stem from the flowing media.

The fluid path and diaphragm positioning and seating enable this valve type to be used for throttling or simple stop operations. They are generally tolerant of particulate matter entrained in the media. Selecting body and diaphragm materials that are compatible with the media are primary elements of achieving a successful application. The diaphragm is a wearing part and should be inspected periodically and replaced when necessary.

Diaphragm valves for industrial use are available in a range of materials and sizes to accommodate light through heavy duty applications.
  • Suitable for inert and corrosive liquid and gaseous media when proper valve body and diaphragm materials are selected
  • Bonnet and valve bodies available in metal or plastic construction
  • Insensitive to particulate media
  • Valve body and diaphragm available in various materials and designs
  • Compact design
  • Automation via pneumatic or electric means
Share your fluid process control challenges with valve application specialists. Leverage your own knowledge and experience with their product application expertise to develop an effective solution.

Sunday, February 18, 2018

Getting Benefit From Waste Steam With a Thermocompressor

steam thermocompressor
Steam thermocompressor enables use of waste steam
in higher pressure applications.
Image courtesy Spirax Sarco
Steam, with its utilization as a means of transferring heat, as well as a motive force, is found in use throughout many industries. The production of steam is a significant cost of operation for any business where it is employed. Steam, after performing its intended function, still contains a comparatively large amount of heat, so methods of recovering or utilizing that heat energy remaining in waste steam is a positive step in conservation.

Energy conservation and energy efficiency have contributed very large cost savings to many industrial and commercial operations over the past two decades. Projects with modest payback periods quickly contribute to the bottom line of the operation's balance sheet. It is not uncommon for  energy conservation and efficiency measures contribute to improvement in the overall functioning of the steam utilization equipment or systems. In order to save energy, it is generally necessary to exercise better control over equipment or system operation by gathering more information about the current operating state. This additional information, gathered through measurement instrumentation, often finds use in several ways that improve productivity and performance.

A thermocompressor is a type of ejector that mixes high pressure steam with a lower pressure steam flow, creating a usable discharge steam source and conserving, through reuse, the remaining heat content of the otherwise wasted low pressure steam. The device is compact and simple, with no moving parts or special maintenance requirements. Two general varieties are available. A fixed nozzle style is intended for applications with minimal variation in the supply and condition of the suction steam (the low pressure steam). Some control is achievable through the regulation of the high pressure steam flow with an external control valve. A second style provides a means of regulating the cross sectional area through which the high pressure steam flows in the nozzle. This style is best applied when specific discharge flow or pressure is required, or there is significant variation in the inlet steam conditions.

Share your steam system challenges with a steam system application specialist. Leverage your own process and facilities knowledge and experience with their product application expertise to develop effective solutions.


Wednesday, February 7, 2018

Plug Valves - Right For Your Application?

industrial plug valve with manual operating handle
Plug valves incorporate design features making them
a positive choice for many fluid process applications.
Image courtesy Fluoroseal, Inc.
There are common components to be found on almost every process system that involves fluid control. Regardless of the operation's scale, pumps, piping, tanks and valves are likely to be part of the system.

Valves, of which there are many types, provide control over the flow rate, direction and routing of fluids in a processing operation. Flow can be started, stopped or modulated between zero and full rate using a properly sized and configured valve. Some valves enable media flow to be diverted to a selection of outlets, in lieu of a single inlet and outlet pair. Specialized valves regulate inlet or outlet pressure, or prevent fluid flow from going in an undesirable direction. All of these capabilities are packaged into differing valve product offerings that present a very large selection array to a process designer or engineer.

Industrial flow control valve types are generally classified according to the structure or arrangement contained within the valve body that provides obstruction to fluid flow. Some of the common types are ball, butterfly, gate, globe, and plug. Surely, there are more valve types, and this article is not intended to list them all. Some of our previous blogs have discussed selection considerations for gate, ball and butterfly valves. This article will focus on one of the oldest valve types, the plug valve.

Plug valves, like ball and butterfly valves, span from fully open to fully closed positions with a shaft rotation of 90 degrees. The “plug” in a plug valve is installed in the flow path within the valve body and rotated by means of a stem or shaft extending to the exterior of the body. Plugs are often tapered toward the bottom and are fitted to a seating surface in the valve body cavity that prevents fluid from bypassing the plug. An opening through the plug, the port, can be shaped to provide particular flow characteristics. There are numerous variants of the basic plug valve which may make it suitable for particular applications. One common variant is the lined or sleeved plug valve, with an insert or interior lining of material that creates an isolating barrier between the valve body and the media. This allows use of less expensive materials for the body construction that may be otherwise subject to corrosion by exposure to aggressive media.

Positive attributes of plug valves.

  • 90 degree rotation from open to closed provides fast operation.
  • With proper configuration, can be well suited for frequent operation.
  • Availability of corrosion resistant liner may provide comparative cost savings because valve body can be constructed of less expensive material.
  • Design is simple and employs a low parts count.
  • Valve can be serviced in place.
  • Generally, low resistance to flow when fully open.
  • Reliable leak-tight service due to tapered plug wedging action, replaceable sleeve, and injection of lubricant in some variants.

Potential issues of concern.

  • Higher friction in the plug closure mechanism may require comparatively higher operating torque than other valve types.
  • Without a specially designed plug, generally not well suited for throttling applications.
  • Rapid shutoff delivered by plug design may not be suitable for some applications where hammering may occur.

Share your fluid control application challenges with a valve and automation specialist. Leverage your own knowledge and experience with their product application expertise to develop an effective solution.

Friday, February 2, 2018

Pressure and Temperature Switches for Rugged Industrial Applications

adjustable pressure switch
This adjustable pressure switch is one of many variants
available to suit every application.
Image courtesy Custom Control Sensors (CCS)
Matching up the most appropriate control device for a processing application, taking all factors into account, may not always result in a selection of the most technologically advanced, complex or full featured solution. Sometimes, all that is needed is a device with a limited performance set, but one that performs its functions reliably in a challenging industrial environment.

Industrial versions of temperature, pressure and differential pressure switches are fitted with appropriate mountings for the process and housings for the installation environment. Hazardous location installation can be accommodated. High current switch ratings and auxiliary functions add to the usefulness of these devices. There are almost countless variants available to accommodate almost every application. Don’t overlook these simple and reliable mechanical devices as candidates for application in temperature and pressure control. Share your application requirements and challenges with product specialists for useful recommendations.