The use of new technologies in valves has to keep pace with the components around them. There have been big advances in electronic control system components in recent years, so valve vendors are looking to keep pace--electronically as well as a mechanically.
According to ARC Advisory Group (www.arcweb.com), control valve suppliers will use intelligent automation at the valve level to provide maintenance, repair, and upgrade services. Smart control valves, actuators, and positioners will offer improved performance and enhanced functionality, which will permit predictive and remote diagnostics.
"With the adoption of digital positioners and fieldbus networks, control valves are finally beginning to shed their image as the weakest link in the loop," according to ARC senior analyst Dave Clayton.
One of the more critical control valve applications is in spraying systems. These systems have a vast array of uses from spraying butter on baked goods to spraying pipe with corrosion inhibitors. Spraying systems must provide precise control of liquid flow and must accurately control concentrations of liquid and air.
AutoJet Technologies (www.autojet.com), a division of Spraying Systems, specializes in turnkey systems that accurately monitor and precisely control spray applications. The company's engineers have some interesting ideas about the future of valve technology.
"Alternatively powered valves would be a good fit for many critical safety/hazardous applications," says Bill Kohley, divisional vice president of AutoJet. "These valves are not governed by pneumatic, hydraulic, or electronic control. A catalyst is instead used to trigger valve operation. The catalyst would be in the transport medium and would be regenerative."
In addition to critical control applications, an alternatively powered valve would also be useful for wireless applications. It doesn't do much good for a valve to have wireless control and monitoring if power is still needed to operate the main actuator or pilot valve. Alternatively powered valves could rely on a small battery to power the valve's electronic control and communications. These valves could be installed virtually anywhere without the need to run wires.
Another means of alternative power was informally introduced at the recent National Manufacturing Week show in Chicago. Now, keep an open mind about this one. I heard that a vendor was at the show discussing a device that extracts electromagnetic energy from the surrounding atmosphere.
According to the vendor, this device captures and concentrates electromagnetic energy present in the surroundings at a level sufficient to power a pilot valve. Such a device could find many uses as a power source in wireless applications.
I was never able to catch up with the vendor, but maybe this column will flush him out, if he's not being kept under observation somewhere for delusion.
Electromagnetic fields may be a practical energy source to power pilot valves, and they could also be used as a means to control flow. In theory, any liquid or gas that can be affected by magnetic fields could be controlled by the proper application of a magnetic field. No conventional valves would be needed to control flow, just an electromagnetic force field.
As a moving and wetted part, control valves are one of the main wear items in any machine. To address wear and maintenance issues, AutoJet engineers envision "self-repairing" valves. These valves could self-monitor, self-diagnose, and fix themselves via electro-mechanical repair modules. These repair modules would i nclude internal replacement components and be capable of closing down the control loop for a repair algorithm.
Closer to the present, current trends are expected to accelerate. "Miniaturization, very low power consumption, and network interfaces will continue to increase in control valves," says Frank Langro, product manager with Festo Corp. (www.festo-usa.com). "We see high-speed valves with very fast switching times in form factors small enough for printed circuit board mounting."
One of the main ways to reduce valve size is to use a concentrated source of energy, such as hydraulics. "Smaller control valves will likely find more and more dependence on electro-hydraulic solutions," observes Jon Frey, product manager of standard products, industrial hydraulics unit, Bosch Rexroth (www.boschrexroth-us.com). "Electro-hydraulic valves use electrical energy to operate a pilot valve and hydraulic energy to actuate the main valve."
In addition to electro-hydraulics, Frey sees other trends. "Improved feedback systems, fieldbus systems, integral diagnostic features, and similar on-board or off-board controllers are on the horizon," adds Frey. "Reductions in power consumption, without sacrificing hydraulic power limits, will challenge designers to maintain performance with less power."
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