Smarter Devices Point to Better Maintenance, Precise Operation, Market Growth
Like people, control valves come in all types, shapes, and sizes. They are found in homes, utility services, institutions, and nearly every manufacturing operation imaginable. These common control components are equally important in a domestic water system as in a large oil or gas distribution line. Valve types range from ball and butterfly to diaphragm and globe; they carry water, air, or gas ...
Like people, control valves come in all types, shapes, and sizes. They are found in homes, utility services, institutions, and nearly every manufacturing operation imaginable. These common control components are equally important in a domestic water system as in a large oil or gas distribution line. Valve types range from ball and butterfly to diaphragm and globe; they carry water, air, or gas and are typically connected to digital networks like DeviceNet, or hybrid analog/digital networks like HART.
Although basic valve design and operation have remained essentially unchanged, technological advancements have brought intelligence to valve applications, increasing efficiency and precision. In a phrase, today's valves are simply smarter. Notes David Clayton, ARC Advisory Group ( www.arcweb.com ) analyst, "We see some new designs for severe service, some new materials of construction for noise reduction, but those kinds of developments are not really new. The real excitement is the increasing intelligence being built into control valves."
Reliability continues to be the most important criterion for control valve selection, regardless of type. Low maintenance is the second most influential factor.
Karlin Wilkes, marketing manager, control valves, Flowserve Corp. ( www.flowserve.com ) concurs. "The primary trend today is to run plants longer and run control valves for longer periods of time without having to repair them or take them out of service. End-users are looking for simple-to-use instrumentation on their valves—on the positioner actually, which is the brains of the valve."
To probe more deeply into control valve applications and requirements, Control Engineering and Reed Research Group, both part of Reed Business Information ( www.reedbusiness.com ) recently asked subscribers in an electronic survey how they use control valves and what they need and expect from them. Survey respondents were involved in the evaluation, specification, recommendation, installation, and/or purchase of control valves for in-plant or OEM (resale) requirements. Here's how they view the control valves industry based on their own experience.
Why and what for?
More than 80% of those surveyed report that their control valves handle liquids. Nearly two-thirds (64%) cite air/gas.
A large majority of respondents (80%) use control valves for in-plant needs; 36% do so for OEM requirements. Nearly half report both continuous and batch manufacturing as their primary application. The results are similar to those obtained in last year's survey. When considering actuators for control valves, respondents said they used pneumatic types the most on ball and V-ball, butterfly, diaphragm, globe, and plug valves. Electric actuators are most common on all other types of valves. More variety in choice of actuator is evident in this year's responses. In the previous study, pneumatic actuators overall were the predominant type for all control valves evaluated.
Asked what medium their control valves were handling, 83% said liquid, again similar to last year's results. Nearly two-thirds (64%) also noted air and gas as frequently handled media. Slurries, powders, and cryogenics made up the remaining responses. (The accompanying graph shows the numbers.)
Nearly two-thirds (62%) of those responding indicate their own maintenance shops provide control valve repair and service. Nearly a quarter uses a third-party service provider and 13% use a factory repair/service.
Solenoid valves are the most commonly specified accessories for most control valves. The exceptions are for globe and butterfly valves. Limit switches and positioner and I/P combinations (both at 53%) are the most common accessories found on respondents' globe valves. Limit switches alone (at 57%) are the most popular accessories on butterfly valves, respondents reported. On the average in the past year, more than half of all control valves were purchased with mounted electrical accessories; 24% of those were located in hazardous environments.
Importance of being reliable
Reliability and low maintenance remain the most important factors when selecting control valves. Regardless of valve type, reliability was far and away number one, named by some four-fifths of respondents. Low maintenance also scored high in importance, with low leak-through rate, repairability, and repeatability named by a significant portion of respondents as well. (See the chart, "Product selection criteria," for the breakdown by valve type.)
That response supports observations by Flowserve's Wilkes on the importance most operations place on maintenance today. Especially in the process industries, he notes, durability and reliability are mandatory. "Minimizing downtime is critical," he says. "Therefore, end-users want smart, diagnostic capability at the control valve—intelligence to tell them in advance that a problem is coming, not that it's already here."
Respondents were also queried about supplier selection. In this case, availability from stock (58%) was most important when choosing a supplier. Cost (at 55%) and repairability (at 50%) round out the top three supplier selection criteria. Also mentioned as important were local technical support, factory technical support, and manufacturer's reputation.
HART, DeviceNet, and Ethernet were the most popular networks used for valve applications. Together, HART (with 28% of respondents) and DeviceNet (with 25%) accounted for more than half the applications. Ethernet was the network used by 16% of respondents. Other networks listed included Modbus, AS-I bus, FOUNDATION fieldbus, and Profibus, each with less than 10% of the total.
Service, repair, maintain
On the average, 40% of the respondents said they needed to repair or service control valves once every three years. Thirty percent said the frequency of repair/service was once every 2 years; the remaining 30% said it was once a year. By a large margin, most survey respondents take care of their own devices. When asked who most frequently services or repairs their control valves, 62% of respondents said they had their own maintenance shops. Some 22% used a third-party service provider, while just 13% used a factory repair service operation. (See graphic, "Repair/service providers.")
However, if the trend toward smart devices continues, changes may be on the horizon. "Suppliers are realizing they cannot only provide intelligent valves to end-users, they must service them as well," says Flowserve's Wilkes.
That trend, along with the increasing importance of valve maintenance, is underscored by ARC's Clayton. "The strongest trend in the control valve market today is the increasing importance that end-users are placing on improving their maintenance practices. As a result, suppliers are expanding their roles to provide diagnostic information and asset management information so that users can know ahead of time if a problem is developing. That gives them the opportunity to prevent a breakdown, to fix the problem according to their schedules, and reduce the number of unnecessary maintenance checks."
What's the future outlook for control valve applications? According to most respondents (60%), their need for these types of valves is expected to stay level, compared to 77% a year ago. However, about a quarter (26%) now say they anticipate an increase in purchases. In last year's survey, only 12% expected an increase in purchases. Only 14% said a decrease was likely.
If these figures and trends are any indication, the control valve market is poised for growth and change. Observes ARC's Clayton, "We've already moved from selling valves to selling intelligent valves that provide repair and maintenance data. Now the trend is for suppliers to offer end-users service programs that monitor and take care of these intelligent valves."
Control valves and related products
For more information on control valves and valve-related products, visit www.controleng.com and the Web sites of the manufacturers of the products below.
Severe service valves
Emerson Process Management/Fisher
Design D4 control valve is a compact, rugged globe valve designed for high-pressure throttling applications in the oil and gas production industry. It is available with pressure ratings to ANSI Class 1500 in 1-in. and 2-in. sizes, and has flanged or screwed end connections. Features include Enviro-seal packing technology for long stem seal life, heavy-duty valve plug guiding, and optional ST Carbide trim. Two additional trim options let users configure the device for sweet or sour applications. Quick-change trim and hammer nut bonnet/body joint help simplify maintenance. www.emersonprocess.com/fisher Emerson Process Management/Fisher
Proportional control valves
Parker Hannifin Corp.
Series D1FP and D1FP*S direct-operated proportional control valves feature high dynamics and maximum flow. D1FP is used for high-accuracy positioning of a hydraulic axis and for controlling force and velocity. It can also be applied where pressure drops up to 315 bar (4,500 psi) across the valve. Driven by a new, patented VCD actuator, the valve reaches the frequency response of servovalves. D1FP*S is a nominal size 04 (ISO 10372) valve that also uses the VCD technology for high response. www.parker.com Parker Hannifin Corp.
High-performance digital positioners
Logix 3200IQ and 500si Series high-performance digital positioners offer quick setup and calibration of diaphragm- or piston-operated valves without the need for additional handheld, software, or configuration/calibration tools. Devices are intended for use in oil and gas production and refining, chemical processing, and pulp and paper production industries. Explosion-proof Logix 3200IQ and intrinsically safe 500si use state-of-the-art piezo technology and inner-loop feedback to provide performance, control, and reliability with minimal air consumption in compact, lightweight, and modular designs. www.flowserve.com Flowserve Corp.
Intelligent valve positioner
Invensys Process Systems
SRD960 intelligent valve positioner combines microprocessor-based valve control with easy installation and operation for a broad range of applications. It can be readily mounted to linear and rotary actuators, and supports all major communications protocols. Device incorporates an IR interface for non-contact operation and allows simple push-button configuration of all parameters. Menu-driven, multilingual graphical LCD shows full text data for such parameters as percent of valve position; actuator position in mm, inch, or percent; and setpoint or loop current. Status and diagnostic messages are also displayed through the LCD. www.foxboro.com/instrumentation Invensys Process Systems
Adaptable valve is wear resistant
ZK control valve combines a valve body and radial stage nozzle with the valve plug acting as a control unit. Features include wear resistance, easy inspection, tandem shutoff, and low sound level. Valve comes in a variety of capacity ranges and works with most actuators on the market. Devices are suited for use in industry and power stations, including leak-off control, drainage and warm-up, level control, and injection cooling. Radial stage nozzle ensures rapid and reliable adaptation to prevailing operating conditions. Valve can be adapted to a new situation by repositioning or exchanging the radial stage nozzle without removing the valve from the line. www.gestra.com Flowserve Gestra
Severe service control valve
78400/18400 Series Lincolnlog control valves are suited specifically for severe service applications and high-pressure liquid letdown service. Design provides effective anti-cavitation performance using multiple stage pressure reductions. Each pressure stage is active and throttles in unison throughout the full stroke, ensuring controlled pressure drop distribution to prevent cavitation. Device provides an axial flow trim design with large flow passages or troublefree operation even in dirty fluid applications. Protected seat feature for metal and soft seat constructions prevents premature seat erosion and wear. Valve can be customized for specific applications. www.masoneilan.com Dresser Masoneilan
Digital positioners for control valves
Pneumatic and electropneumatic positioners for control valves, both smart and analog, include the TZID electropneumatic and AV pneumatic lines. TZID-C smart device is a robust, intelligent, modular positioner. It is configurable and features digital Fieldbus communications and diagnostics. Type AV device measures the actual position, or percentage open, of a valve or damper. It automatically controls this position to ensure it matches a given control input signal by controlling the pressure applied to the pneumatic actuator mechanically connected to the valve or damper. Pressure is proportional to the difference between the actual and designed positions. www.abb.com ABB
Specialty valves for process control
Tube bore WK74 Series clean valves and high-performance cryogenic ball valves provide critical service environment operation in temperatures ranging from -320 to 600 °F and at pressures from an average 150-6,000 psi. Clean valves are stainless-steel ball valves for high purity and aseptic processes. FDA-approved line is designed for temperature control where valves fill and drain dry powder, liquids, and solid foods into and out of kettles. Cryogenic valves are shutoff devices for intermittent and continuous flow applications at temperatures to 320 °F. Series meets the demands of oxygen, hydrogen, ammonia, CO 2 and nitrogen. www.worcestercc.com Flowserve/Worcester
Actuator with flow throttling option
Apollo Div., Conbraco Industries Inc.
Apollo AE Series electric actuators are now available with a factory-installed 4-20 mA positioner that improves control in applications requiring flow throttling. Designed for quarter-turn valve and damper applications, the NEMA 4 and 4X device offers 4-20 mA control-activated incremental modulation. Actuators provide push-button set up, automatic calibration, signals for selectable input, position feedback, and fail position. Other features include an adjustable dead band and locked output stall protection. www.conbraco.com Apollo Div., Conbraco Industries Inc.
Cage-type control valves
Spirax Sarco Inc.
C Series control valves come in sizes from 1 in. to 8 in. (DN25 to 200) with valve plug closure to ANSI class IV, V, and VI. Offering pressure ratings conforming to ANSI 300 and ANSI 600, the valve comes in carbon steel, alloy steel, or stainless steel body materials for a wide range of applications. Module design lets a single valve envelope meet a variety of control needs. Cage-guided balanced plug is designed to provide precise control over high differential pressures. One, two, and three-stage designs are available to minimize cavitation and aerodynamic noise. Cage-retained internals can be serviced with the valve in-line. Features include highly repeatable and easily adjustable single-spring actuation. www.spiraxsarco.com/us Spirax Sarco Inc.
Electrically actuated ball valve
George Fischer Inc.
130 Series electrically actuated ball valves feature the new EA 21 electric actuator, specifically designed to complement modularity and flexibility of 546 Series valve and provide a system approach to piping system design. Actuated valve series includes model Type 131 in polypropylene, Type 132 in PVDF (polyvinylidene fluoride), and Type 133 in PVC and CPVC, all available in size 3/8 in. through 2 in. Designed for long service life of 250,000 cycles, the EA 21 actuator comes with integrated emergency manual override and automatic adjustment of voltage and frequency for on/off or process control applications. www.us.piping.georgefischer.com George Fischer Inc.
CFV maintains flow with pressure change
Dymatrix Constant Flow Valve (CFV) maintains constant flow with changes to both up and downstream pressures. Device is suited for blend applications because it reacts effectively to supply pressure changes and maintains high repeatability. Valve controls flow rates from 10 to 2,000 cc/min, features PTFE construction, and is offered in www.asahi-america.com Asahi/America Inc.
Valve terminal supports up to 64 solenoids
MPA valve series manifold offers I/O points to support up to 64 solenoids (32 valve positions). High-speed internal serial bus allows it to be easily reconfigured and accommodate advance modules. Interchangeable valve and electronic modules make it easy to service. Features include MPA valves with flow rates up to 360 l/minute and broad operating voltage and pressure ranges. Label holders on sub-bases provide durable identification of valves. www.festo.com/us Festo Corp.