Control Valve Actuators
Market for control valve actuators is growing, with 90% expecting to buy the same or more such products in the next 12 months as in the past year, according to research from Control Engineering and Reed Corporate Research. For users of control valve actuators, reliability, repeatability, and low maintenance are the most important features, the research showed, no doubt because the majority of t...
Market for control valve actuators is growing, with 90% expecting to buy the same or more such products in the next 12 months as in the past year, according to research from Control Engineering and Reed Corporate Research.
For users of control valve actuators, reliability, repeatability, and low maintenance are the most important features, the research showed, no doubt because the majority of the work is done in house when actuators need repair or service. Electric and pneumatic actuators are used about equally, at just over 40% of respondent locations. Primary applications for control valve actuators are food and beverage; chemical; industrial and other machinery; and other manufacturing and processes. Pharmaceutical and petroleum/refining applications also make the list.
In the last week of November 2006, an email was sent to a random subset of Control Engineering subscribers who say they specify, recommend, and/or purchase control valve actuators. In the email, respondents were asked to visit a Web site that contained a survey with incentive to enhance response. Results are based on 267 responses.
Among those specifying, recommending, and/or buying control valve actuators, 79% do so for in-plant requirements and 34% buy for OEM (original equipment manufacturer) needs. Broken down to reflect combined use, 13% buy both for OEM and in-plant use, 21% purchase only for OEM use, and 66% only for in-plant use.
Survey respondents could check as many features as applicable for control valve actuators. Percentages are for ratings of 'important' or 'very important.'
The combination of continuous and batch manufacturing is the most prominent application (46%) of control valve actuators at respondents’ locations. “Continuous manufacturing only” is applied at 22% of locations. “Batch manufacturing only” is used at 16%. Remaining responses were “other,” HVAC, and process.
Respondents mention liquids as the media most handled by control valves, 62%; air/gases 31%; slurries 4%; and powder 3%.
Electric and pneumatic type actuators are used about equally at respondent locations, 42% and 41% respectfully, with manual about 16%. Also, the predominant choice is to have the actuator integrated with the valve (one assembly) at 76%, with the remaining 24% adding the actuator separately.
Among a variety of control valve types, pneumatic type actuators were used most often, 76%. Manual and electric type actuators were used less than pneumatics with all valve types. For most valve types, electric actuators were used more than manual.
They need to work
Reliability (96%), repeatability (81%), and low maintenance (77%) were named the most important features when specifying, recommending, and/or buying control valve actuators. Nonetheless, when actuators do break, 66% of the respondents said that the ability to fix them (repairability) was among most important features they sought (see related graphic).
In selecting manufacturers for control valve actuators, repairability (70%) and availability from stock (64%) rated highest among attributes, with cost concerns and manufacturers’ reputation tied at 58%, factory technical support 53%, local technical support 47%, online troubleshooting 22%, services package 19%, online ordering 13%, and “other” concerns pulling 22%.
For al the talk of outsourcing, 64% of survey respondents say they repair and service control valve actuators in house, far ahead of other options.
For those using a network for valve actuator applications, Ethernet TCP/IP (native) and HART are used most, in a statistical dead heat at 21% and 20%. DeviceNet is 14%, Modbus 11%, FOUNDATION fieldbus, and Profibus about tied at 9% and 8%, with the remainder divided among seven other means of communication and “other.”
Repair and service of control valve actuators varies, with 38% once every three years, 29% every two years, and 32% every year. The vast majority, 64%, repair and service in their own maintenance shops; 19% rely on the supplier; and 13% on a third-party, with the small remainder going to system integrators and other providers.
For 41% of respondents, every control valve purchased will include an actuator (integrated or as an add-on), for 17% less than half of valves purchased will include an actuator. For 30% of respondents, more than 80% of their valve actuator purchases will be located in hazardous environments.
Emerson Process Management is the manufacturer selling the most control valve actuators to respondents over the last 12 months. Purchases from the remaining manufacturers are split among numerous companies, with a dozen in double-digit percentages (see products from leading companies below).
Each survey participant purchased an average of 246 control valve actuators during the past 12 months, with average spending per respondent for that time at $235,213. A small number of large purchasers increased the average spending. Median numbers were lower. Number of control valve actuators will increase among 29% of respondents in the next 12 months, with 61% purchasing about the same amount. Only 10% expect a decline.
Areas of growth
An ARC Advisory Group ( www.arcweb.com ) survey supports Control Engineering subscribers’ prediction of growth. The September 2006 study, “Control Valve Worldwide Outlook,” also covering actuators and positioners, estimates global growth in control valve shipments, from $3.5 billion in 2005 to more than $4.5 billion in 2010. ARC noted, “Hardware revenues are resurgent, fueled by the explosive growth in new projects, particularly in Asia. Growth is also strong in the oil & gas industry” especially with growing thirst for energy.
Control Engineering “Product Research” reports are available free at / .
Mark DiVito, Reed Corporate Research, and Jeanine Katzel, Renee Robbins, and Peter Welander, Control Engineering , also contributed to this article.
Valve actuator products
The companies below, identified by Control Engineering subscribers as leading providers of control valve actuators, offer the following products. To find other suppliers, search www.cesuppliersearch.com . To find system integrators with related expertise, go to www.controleng.com/integrators .
Spring-opposed diaphragm actuators
Emerson Fisher spring-opposed line of diaphragm actuators for control valves provides dependable on-off or throttling operation for many applications. Spring rates, travel stops, and manual operators are available for most control valve uses. A molded diaphragm is said to have excellent linearity between loading pressure and resulting travel and yield high thrust output. The actuators exhibit a high degree of dynamic stability and frequency response in providing accurate, quick-acting valve control. Featuring rugged thick-wall cast iron and steel construction, they provide increased stability, corrosion protection, and protection against deformation should over-pressurization occur. They come in direct or reverse acting configurations and are suited to a variety of globe and rotary valves.
Emerson Process Management
Actuator Division of Parker Hannifin Corp. introduced the new P5T2 Short-Stroke Thruster, which has short-stroke, heavy-duty performance in a smaller footprint than conventional thrusters that use external cylinders. The design is said to suit packaging, conveyor, and assembly application, which often have limited space and substantial loads. The series handles frequent stops on conveyor equipment, tamping and pressing on packaging machinery, and unloading/loading and clamping processes on assembly machinery. Eight bore sizes are available between 12 and 100 mm with strokes up to 200 mm. Maximum operating pressure is 1MPa (10 bar/145 psi). They have standard through-hole mounting; rear mounting can be special ordered. Top porting is standard. Rear and side porting are available. A true rod-lock mechanism, which stops the unit in current position upon loss of air pressure, is available on 32-100 mm bore sizes. It has an aluminum body and end caps; steel tool plate, support rods, and rod bolts; and a stainless steel piston rod. Standard nitrile seals operate at temperatures between -18 to 74 °C (0-165 °F). Fluorocarbon seals are available for high-temperature applications and have an operating range of–18 to 121 °C (0-25 0 °F). A PTFE-impregnated composite bushing is standard on all P5T2 models and provides high load-carrying capabilities with excellent resistance to shock loading. Optional linear ball bearings provide precision operation with very low friction and wear.
Parker Hannifin Corp.
More diagnostics for smart electronic valve actuator
Flowserve Corp. Limitorque MX smart electronic valve actuator has a patented absolute encoder with increased span (no battery backup needed), improved diagnostics capability, and built-in self-test (BIST). Its control platform verifies and validates the integrity of its components, a design that helps companies meet Safety Integrity Level (SIL) requirements of IEC 61508. MX is designed to provide users with predictable, reliable, and safe operation in rigorous, extreme applications. It has circuit protection technology and easy-to-use menus in six languages, and Hall-effect devices to eliminate potentially troublesome reed switches, the company says. Torques up to 1,700 ft-lb (2,307 N m) and thrust ratings up to 75,000 lb (333 kN) are available. It operates up to one hour without power and has communication options for Modbus, FOUNDATION fieldbus, Profibus, and DeviceNet. Display rotates 180°. Bluetooth wireless connectivity is optional with range up to 10 m. Software is available to transfer diagnostic information to a PDA, laptop computer, or cell phone.
Light, compact pneumatic valves
Some machine and system applications call for light and compact pneumatic valves. Rexroth HF03 LG is a lighter-weight valve terminal system with a high flow rate, up to 700 liter (0.7 Cv), said to be ideal for use in automation, machine construction, or the automotive industry and is suitable for medium-sized and larger actuators, which require low weight when a valve is mounted onto the robot’s arm. Modular design can be extended up to 12 valves, one at a time. Identical base plate for all valve functions, the plug-in procedure, and integrated plug connections ensure that valve functions can be changed quickly and easily, without having to first disassemble the valve terminal system. Polymer end plates decrease weight. Forward-facing pneumatic and electric connections create extra mounting options and keep installation dimensions compact to suit individual space requirements. Whether multiple plug or fieldbus, the connection type can be converted without disassembling the valve terminal system, saving time. It conforms to IP65 (NEMA 4) protection class for use in harsh environments.
Double diaphragm actuators enhance sensitivity
Metso Automation’s patented, pneumatic double-diaphragm Neles actuators aim to enhance control accuracy and sensitivity and ensure compact size with rack and pinion design. Diaphragm actuators offer sensitivity for control valve applications. Case-hardened steel used for gear components adds durability. It offers backlash-free connection to the valve and positioner while avoiding linkages and external pipework. Also available is a spring-return design in which the two diaphragms work against the spring. Company says it has sold more than 40,000 Neles double-diaphragm actuators by end of 2006, many to major pulp- and paper-processing plants worldwide.
Metso Automation Inc.
Software simplifies actuator selection
Conbraco Apollo Actuator Wizard is said to drastically simplify actuator selection for a specific valve application. Through a series of short questions, Actuator Wizard Web-based software responds to answers, providing information to order the parts for a specific application. The wizard asks if it’s a Conbraco valve or other brand, the part number, then some additional information, such as pneumatic or electric, valve media, and type, temperature, pressure, and material requirements. It asks if the actuator is double acting or spring return, about air supply and cycling requirements, and if there are any specified sizing safety factors for the actuator.
Double-acting digital actuator positioner
The new double-acting Masoneilan FVP (Fieldbus Valve Positioner) is an intelligent digital valve positioner, certified by the Fieldbus Foundation. It can be mounted on double-acting actuators of any manufacturer, is said to use technology more forgiving to airborne contaminants, and requires less maintenance compared to other designs. Non-contact position sensor mechanism eliminates potential for wear of the valve position feedback sensor. It has automatic stops and automatic tuning and is calibrated and commissioned in a matter of a few minutes. Diagnostics can be integrated with various leading software for asset management.
Don’t service this actuator for 10 years
ABB’s Contrac electric actuator provides intelligent or “smart” modulating action to position the control valve precisely within its operating range in response to a 4-20 mA dc control signal. Different-sized models are available for torque requirements ranging from 80 to 12,000 ft lb. Start-up torque is 1.2 times rated with “break-away” torque being twice the rated torque. These actuators can have fast stroke speeds that provide fast response to needed changes in valve position. Speeds are expressed in seconds for a 90° travel of the actuator lever arm. The actuator has oil-lubricated spur gearing in a sealed, dust-tight enclosure for high operating efficiency, high torque outputs with lower electric motor horsepower, and a 10-year maintenance cycle for an oil change. An integrated motor brake enables the drive to hold valve position in the event of power failure or switch-off. The drive unit contains means to monitor several operational functions such as valve position, frequency of motor reversals, and actuator internal temperature. Values are stored in the electronics unit for future use in analysis of performance. Available PC-based software can help with that.
Remote operation intelligent positioner
The Foxboro SRD991 Intelligent Positioner, from Invensys Process Systems, is said to provide easy configuration and operation of pneumatic valve actuators from local and remote locations. Available with multiple communications protocols, including HART, FOUNDATION fieldbus, or Profibus-PA, the SRD991 is certified for installations involving explosive atmospheres and can be mounted on rotary or linear actuators. It operates from control systems, controllers, or PC-based configuration and operation tools—including FDT software. SRD991 features auto-start with self calibration, self diagnostics, status, and diagnostic messages. Available for single or double acting applications, it offers IP65 and NEMA 4X protection, is approved for SIL applications, and is intrinsically safe according to ATEX and FM/CSA.
Positioner reduces compressed air use
A unique feature of Sipart PS2 valve positioner from Siemens is its extremely low air consumption. When balanced, the PS2 consumes virtually no air, reducing electricity costs by $120 per year per valve when compared to conventional designs, by decreasing compressed air use. Sipart PS2 controls the final element of pneumatic linear or part-turn actuators, where the positioner moves the actuator to a valve position corresponding to the setpoint. Additional function inputs can be used to block the valve or set a safety position. A binary input is present as standard in the basic device for this purpose. PS2 communicates through either Profibus PA or HART protocols and can also be operated through a Microsoft Windows-based HMI (human machine interface) with simple PC software.
Siemens Energy & Automation Process Instrumentation