�ǳ�web Knowledgebase - electronic valve

DVP High Flow Electronic Proportional Control Valve

Rachel Desenberg — Thu, 27 Jul 2017 18:11:08 +0000

Category:

�ǳ�web's next-generation DV Series valve is available in a 2-Way proportional flow control version! The DVP Series provides a high degree of control and customization. Available in manifold mount or #10-32 mounting styles, the DVP provides fast response times and exceptionally long life.

Features:

• Industry standard for leak-free operation
• Over 1,000,000,000 cycles
• Extremely low hysteresis
• Fast response time
• Large flows in a small, sleek design
• Low heat rise/low power
• Robust stainless steel "spider" flat armature spring
• CE, RoHS compliant
• Proudly Made in USA

Valve Type: 2-Way, Proportional
Medium: Air or Compatible Gases (40 micron filter)
Pressure Range: Vac* to 100 psig
Max. Flow Tolerance: +10% / -0%
Power Consumption: 1.9 watts at 72˚F, 2.5 watts max.
Temperature Range: 32 to 120˚F
Voltage: 10 VDC (0.190 amps) or 20 VDC (0.095 amps)
Mounting: Manifold, #10-32 Male Stud
Seal Material: FKM standard; Nitrile, EPDM & Silicone available
Wetted Materials: Stainless Steel, PPS
Certifications: CE, RoHS, REACH

*Vacuum applications are reverse flow

�ǳ�web's DVP series proportional solenoid valves are precision-built 2-way flow control valves, utilizing �ǳ�web's unique valving principle. This powerful series was designed as the next generation of �ǳ�web's best-selling original EV line. With a lifespan of over a billion cycles; a solid, compact design; and extremely high flow rates, these valves are suitable for many applications across numerous industries.

The DVP series provides air or gas flow control and varies the output flow based on the current input to the solenoid. The consistent gain (see chart) of this valve provides a high degree of control.

Controllability and overall value are the main features of the DVP series. The valve may be controlled using DC current, open or closed-loop control, and even PWM (pulse width modulation) to cover a large range of applications.

Tags:

Proportional

dv-p

DVP

electronic valve

�ǳ�web Releases New ST Series 8 mm Electronic Valves

Chris Agricola — Fri, 02 Jun 2017 19:26:22 +0000

Category:

Advertising

�ǳ�web ST Series 8 mm 3-Way Electronic Valves

These direct actuating valves offer an extremely fast response time for accurate dosing of minute volumes with the same long life you expect from the original �ǳ�web EV line of electronic valves, now in a 8 mm cartridge package.

This valve was designed with a unique patented valving principle using �ǳ�web’s robust stainless steel “spider”, with only one moving part that travels less than 0.007”.

Due to very low moving weights, they are extremely quiet and emit very low vibration. Subminiature size and low energy consumption make them ideal for many medical and diagnostic applications.

Standard products offered will fit the needs of most applications, however this series can be fully customized according to the user’s unique requirements. Consult �ǳ�web with your specific application.

• 1,000,000,000+ cycle life
• Extremely small dead volume
• Low vibration and noise
• Exceptionaly repeatability and reliability
• Compact and ideal for sub-assemblies
• 100% tested

Request a FREE Catalog
or
Download the Electronic Version (PDF)

Sign Up to Receive Monthly Emails about �ǳ�web products, news and applications

Tags:

An Overview of Pneumatic Valves

Rachel Desenberg — Thu, 09 Jun 2016 20:41:53 +0000

Category:

Pneumatics 101

Compressed air pneumatic systems require methods of safe and precise control of the actuators unique to their accoutrement. Although the medium is fluid, just as hydraulic or process water systems, the execution of control is different in many ways than with a liquid. What is shared in the conduction of any fluid power medium is the need for valves to control force, velocity and direction of movement.

Air Preparation

Pressure relief valves will control pressure at their inlet port by exhausting pressure to atmosphere. Relief valves are typically used only in receivers or air storage devices, such as accumulators, as a means to prevent excessive pressurization. As such, relief valves are often called safety valves and are not typically appropriate for use anywhere but the air preparation stage.

Pressure regulators in pneumatic systems limit pressure downstream of the unit by blocking pressure upstream at the inlet. Regulators are used in the air preparation stage, as well as in control of cylinders and motors. The letter R in the acronym FRL stands for regulator, which is installed downstream of the receiver tank, but before the circuit they are regulating pressure for.

Sometimes multiple stages of pressure reduction are required, especially with a large centralized compressor and receiver feeding various workstations. A regulator can control pressure within the main grid of distribution plumbing, but sometimes air is piped directly to an FRL at each workstation or machine. Pressure at this main header could be 120 psi or more, but a branch circuit could be regulated at 90 psi, for example. Most regulators are capable of relieving downstream pressure, which prevents that downstream pressure from elevating as a result of load-induced pressure or thermal expansion.

» Exhaust Valves
» Flow Controls
» Pressure Regulators

» Filters
» Regulators
» Lubricators

» FRL Combinations
» Gauges

Pressure regulators can be had as stand-alone units, but sometimes a filter is attached to kill two birds with one stone. Regulators are most often available as a component of a modular set, with a filter, regulator, lubricator or dryer etc., and can be assembled in any combination. The regulator will have an inlet port, outlet port and a port for the pressure gauge, which they are most often included with.

Pressure regulators can also be used to control pressure for individual actuators, such as an inline regulator or work-port mounted regulator. These are typically quite small and included with reverse flow check valves, as would be required for double acting function of a cylinder, for example. Further still, differential pressure regulators are offered by some manufacturers, to maintain a set pressure differential between the two ports, rather than just maintaining downstream pressure. It should be noted that all pressure regulators are adjustable, most often with screws or knobs.

Flow Controls

Also common in pneumatic systems are valves to control flow. There are fewer available types of flow valves compared to pressure or directional valves, but most circuits apply them to make for easy adjustment to cylinder or motor velocity. Controlling velocity in pneumatic systems is more complex than in a hydraulic system, because pressure differential between the work ports of a cylinder plays a larger part.

Flow control valves for pneumatic systems are quite simple, usually available in two configurations used in two different ways. One configuration is merely a variable restriction, with a screw or knob adjustment to open and close a variable orifice, which is also often referred to as a needle or choke valve. The other type introduces a check valve, which allows free flow in one direction, and restriction in the opposing direction. For whatever reason, this valve has hijacked the name flow control all for itself.

Flow control valves are applied in two different ways; meter in or meter out. Meter in is the method of controlling the rate of airflow as it enters a motor or cylinder. When metering in, a cylinder will move rapidly with high force and efficiency, but the motion of the piston is prone to spongy and unpredictable movement. When metering out, the cylinder velocity is more stable and repeatable, but efficiency and dynamic force are lost to the energy required to push past the flow control. Regardless, most pneumatic applications operate using meter out flow controls, because the disadvantages are easy to overcome by increasing upstream pressure.

» Right Angle Flow Controls

» Push-Quick Flow Controls

» Exhaust Valves

A method of increasing cylinder velocity, typically for double acting or spring-return cylinder retraction functions, is to add a quick exhaust valve to the cap side work port. Because cylinders retract faster than they extend as a result of differential air volumes, it is harder to evacuate the cap side air volume without oversized valves or plumbing. A quick exhaust valve vents directly to air from the cap side work port, and massively reduces the backpressure created upon retraction, permitting very rapid piston velocity.

Pneumatic directional valves are available in many sizes, styles and configurations. At the basic end of the spectrum is the simple check valve, which allows free flow in one direction and prevents flow in the reverse direction. These can be installed anywhere from right after the receiver to within a flow control valve itself.

As directional valves grow in complexity, they are specified under a general naming practice related to the number of positional envelopes of the valve and the number of work ports in the valve, and specifically in the order described. For example, if it has five ports, port 1 will be for pressure inlet, ports 2 and 4 for work ports, and 3 and 5 for the exhaust ports. A valve with three positions will have a neutral condition, extend condition and retract condition. Putting it all together, this describes a five-way, three position valve, also referred to as a 5/3 valve. The common configurations seen in pneumatics are 5/3, 5/2, 4/2, 3/2 and sometimes 2/2 valves.

Also part of the description of a directional valve is its method of both operation and positioning. The valve operator is the mechanism providing the force to shift the valve between its positions. The operator can be a manual lever, electric solenoid, an air pilot, or cam mechanism, to name a few. Some valves are a combination of these, such as a solenoid pilot valve, which is a tiny valve providing pilot energy to move the mainstage valve. Positioning of any valve is achieved by either a spring, such as with a 5/2 spring-offset valve, or with detents in 5/2 detented valves.

A 5/2 spring-offset valve will return to its starting position when energy is removed from its operator, like de-energizing the coil, or removing pilot pressure. A 5/2 detented valve will stay in the position it was last activated to until the operator switches it again.

Pneumatic valves are manufactured in various incarnations. Poppet valves are simple, using a spring to push a face of the poppet down on its seat. Construction can be metal-to-metal, rubber-to-metal or even with diaphragms. Poppet valves can often flow in one direction, just as a check valve, but need to be energized to flow in reverse. They are limited to twoor three-way port configurations, although they can mimic four- or five-way valves when used in parallel. They offer typically high flow conductance for their size, and are generally very resistant to contamination.

Spool valves use a notched metal cylinder that slides within a precisely machined body, drilled with three to five ports, or even seven ports if the valve is pilot operated. Low-end valves consist of only a spool and body, and are prone to internal leakage. Better valves use seals in the body or spool to prevent leakage between ports. High-end spool valves are constructed with precision, often requiring fine lapping procedures during manufacturing, and with their tight tolerances, often require few seals, improving reliability and longevity. Other forms of high-end valves use a sliding block of metal or ceramic, which is not only efficient, but also extremely resistant to contamination, making them great for dirty environments.

Mounting Considerations

Pneumatic directional valves come in both standard and non-standard mounting configurations. The non-standard valve is constructed at the whim of the manufacturer, with port layout, operator style and mounting options unique to their product. They can be inline, subplate mounted or sectional stacks mounted in a row. Because each manufacturer does mounting differently, it is best to research the product appropriate for your application.

Luckily, most manufacturers have lines of standardized valves suiting one or more specification, such as ISO 5599-1, with its staggered oval ports; this means one manufacturer's valve will fit the subplate or manifold of another manufacturer's. Port and electrical connections are standardized with most valves as well. NPT ports are common, but many new valves come with push lock fittings on the subplate itself. Electrical connectors for standardized valves are frequently DIN, mini-DIN or with field bus connection, making the operation of a dozen valves as easy as one connector.

By Paul Heney

Tags:

electronic valve

pneumatic valve

Building a Billion-Cycle Valve

Chris Agricola — Thu, 11 Jun 2015 18:19:27 +0000

Category:

Applications

Original Article, JULY 2014
BY KEN KORANE

Here's how engineers used advanced software and innovative manufacturing techniques to produce a next-generation, high-flow valve.

Like most everyone today, machine builders want more for less. That certainly holds for users of pneumatic valves, who are clamoring for higher flow capacity, but not at the expense of buying a larger valve. At �ǳ�web Instrument Laboratory, Cincinnati, such demands have spurred the development of a new line of two-way solenoid valves called the DV. Its unique construction builds on technology developed for the company's proven and reliable EV valves. But it provides five to six times more flow in an equally compact design. And, its rated life exceeds 1 billion cycles.

Engineering Challenges
Like its predecessor, the DV consists of three basic subassemblies: housing and solenoid; a base with a nozzle that channels flow; and a "spider" spring assembly that includes a poppet, overmolded seal, and puck-shaped magnet. Development of the DV was challenging, to say the least, admits �ǳ�web Design Engineer Dave McBreen. His objective was upgrading this basic layout to substantially increase flow capacity, without markedly changing the valve's overall dimensions.

Though a serious design constraint, small size is a must because users rely on banks of these valves to handle a variety of tasks, he explains. "They're used in packaging equipment, medical devices, analytical instrumentation, and many other places. Industrial applications typically have multistation manifolds where valves are mounted as close together as possible to minimize space requirements. Thus, the DV valve's OD couldn't exceed three-quarters of an inch."

The first obstacle for the �ǳ�web engineers was designing a solenoid coil that fit the available envelope and could generate sufficient power to shift the valve at high pressures — or determine it was impossible. Product specs called out maximum size, minimum power levels, and maximum flow at standard pressures of 100 psi. And response time had to be in the 10 to 15-msec range to permit high-speed operation.

The question was, how much magnetic force could a coil generate, and how big a magnetic puck was needed to pull against a half-pound preload? "With coil design, it's all about amp-turns," explains McBreen. "You get the most bang for your buck by wrapping out and growing your diameter, as opposed to growing taller." Coil technology hasn't advanced much since the days of the EV's development, so McBreen found no magic bullet in the latest generation of solenoids. "It's still wrapping wire around a spool," he says. They did consider voice-coil actuators, but found them too expensive and with unproven long-term reliability. "It was in our design's best interest to stay with a standard wound coil," says McBreen.

Faced with so many variables, and so many iterations, �ǳ�web engineers developed a Coil Calculator software program to streamline the design process. It let them optimize the coil in relatively short order.

"We're basically designing a bobbin," says McBreen, "and we know the inner and outer diameter of the spool, how tall it is, and the wall thicknesses. The software lets us plug in the geometry and then enter different wire gauges. It shows us how many amp-turns we can get with a 34-gauge wire, a 32-gauge wire, and so on. We key in on the combination that gets us close, then make finite changes to the bobbin geometry to tune it in."

They chose to develop the program in-house, rather than rely on off-the-shelf software, because they had very specific goals. It's like buying an FEA package with lots of options that you don't need, and isn't well suited to your problem, he explains. "The Coil Calculator gave us exactly what we were looking for, it was obviously the way to go."

Engineers used the calculator in tandem with EMS, a 3D electromagnetic field simulator program from Montrealbased ElectroMagneticWorks. It let them tweak the resulting magnetic circuit, with impressive results. "I was shocked at the accuracy," admits McBreen. The first prototype met all physical requirements and performed to within 5% of predictions, which is in line with standard coil tolerances.

Higher Flow
The next engineering hurdle was designing flow passages that upped the valve's capacity, but not its size. "If you look at the nature of a two-way valve, especially a manifold-mount valve, air enters through the bottom, flows into the valve, then makes a 180° turn and travels down through the outlet holes and back into the manifold. That alone creates restrictions that you have to design around, to get the necessary flow," explains McBreen.

They examined many different orifice and channel shapes in the quest to maximize flow. For example, certain nozzle geometries, and radii on the nozzle edges, gave smoother, more-laminar conditions that resulted in consistent and higher flow. An added benefit was lower friction between the orifice and mating nozzle seal, which reduced preload and wear.

The DV is a normally closed valve. The poppet with an overmolded seal presses against the nozzle and closes off flow. Energizing the solenoid lifts the magnetic puck towards the core until it bottoms out against the bumper. In the manifold-mount version, air then flows through the #10-32 port, through the orifice, and into the internal chamber. A series of slotted holes surround the molded nozzle, permitting air to flow out to the manifold.

Engineers relied on both computational fluid dynamics analysis, in this case Flow Simulation CFD from Dassault Systémes SolidWorks, based in Waltham, Mass., as well as on physical testing—validating concepts with machined prototypes. CFD proved to be an excellent tool for modeling flow through individual valves and examining various options, says McBreen. However, simulating a bank of manifold-mounted valves was rather time consuming, he admits, as there are so many pathways to consider.

Spider Spring
Perhaps the most visually interesting component within the DV is the spider, an unusual spring that shifts the valve when the solenoid deenergizes. Developed by �ǳ�web engineers, the unique configuration lets it generate sufficiently high force from an extremely compact spring with very little movement—the DV has only 0.018 in. of stroke and about 0.018 in. of spring preload. Minimal stroke is necessary, says McBreen, to ensure precise control and maximum flow at operating frequencies as high as 32 Hz.

Getting the configuration just right required intensive FEA analysis in SolidWorks on various spider designs. "We wanted the legs as long as possible, to get the longest stroke within our space limitations," says McBreen. Thus, the number, shape, length, and layout of the legs, the radii of transitions, and many other factors were studied and adjusted to come up with the proper stroke and spring rate—while keeping stress levels sufficiently low to ensure extremely long life.

The spider spring, with its long, narrow and curving legs, would be difficult to machine or fabricate by stamping, but it is pretty simple to etch, he notes. The process starts with a flat sheet of 0.020-in.-thick 17/7-PH stainless steel, which is then chemically etched to the final configuration. A finishing operation removes stress risers and gives it a glasslike surface. The process holds tolerances on some features to ±0.001 in., so there is little variation from part to part. That helps ensure consistent performance from one valve to the next.

Testing, Testing
Engineers tested several evolutions of the valve to prove out the design, evaluate different manufacturing techniques, and ensure the DV's durability. And given the billion-cycle intended life, that required some patience—as it involves running the valves at 32 Hz and 24/7 for a year. The test rig required solid-state relays because mechanical contactors would burn up under such demanding conditions. Units are tested at various pressures ranging from 0 to 100 psi, response time was regularly monitored, and valves were checked for leaks and seal wear every 50 million cycles.

McBreen's main concern was that the overmolded poppet seals would peel off the base metal over time, but that was never an issue. However, one unforeseen dilemma on an early prototype was the appearance of fretting corrosion between the magnetic puck and housing.

The initial design mandated an extremely small gap between the two parts, to take full advantage of the available magnetic field, McBreen explains. "Apparently, it was a bit too close."

The compact DV is a two-way solenoid valve that provides five to six times the flow of previous versions.

The spider spring shifts the valve when the solenoid deenergizes and has a stroke of only 0.018 in.

Fixing the problem wasn't a simple as merely widening the gap, however. "If you make the clearance too big, then you lose a percentage of your magnetic force." He again turned to the EMS software to refine dimensions and ensure the puck stays centered and glides with minimal friction—all while maintaining the needed magnetic-field strength.

Such setbacks are inherent to engineering, says a pragmatic McBreen. "It's part of the optimization process. Analysis only shows you so much and gets you in the right ballpark. That's why you test it, to find out what relative changes you can make to improve the end product."

Manufacturing Issues
Because the DV has a number of working components, and an extremely short stroke, part tolerances could have been a nightmare. "If you're not careful, the tolerance stack-up will match the stroke and the valve won't work. The battle is how to control those tolerances without driving manufacturing costs through the roof," states McBreen. "It gets a little tricky, but there are certain features we can control very tightly, so it eliminates some of the stack," he says. That's why parts are manufactured at �ǳ�web's facilities in Cincinnati. "One of our niches is being very good at machining parts with very tight tolerances. We have the right equipment, we've been doing it for a long time, and it's less costly than using outside vendors."

Ensuring the DV is easy to manufacture and assemble was also a prime concern from the beginning. One example McBreen cites is opting for a molded nozzle, versus a machined one. Machining small orifices in stainless steel and holding extremely tight tolerances is difficult, and the parts take too long to make. Instead, a key supplier molds the nozzles from dimensionally stable Ultem and holds ±0.001 in. on the ID and other critical dimensions. And they tightly control the process to ensure excellent repeatability, he says.

The plastic nozzle also lets manufacturing personnel pop in a radial seal by hand, and it seats against the housing and nests in proper relation to the spider. The subassembly gives the necessary preload with near-zero friction on liftoff.

Assembling the DV involves simple press fits with no shimming. The three subassemblies are put together using simple tools, and every valve is automatically tested prior to shipping to the customer. Compared to the EV valve, the DV's streamlined manufacturing procedures save several minutes of production time for each part – which adds up to sizable time savings in highvolume production.

Product Specs
The DV is rated for flows of 100 lpm at 50 psi with a 0.070-in. orifice, and 100 lpm at 100 psi with a 0.052-in. orifice.

It's suitable for service with air and other compatible gases, and it is currently being tested with water. The valve base is made of 303 stainless steel, and all the magnetic components are 430F stainless steel. Other "wetted" materials include Ultem and polyphenylene sulfide (PPS). Ultem is a thermoplastic polyetherimide resin with outstanding elevated thermal resistance, high strength and stiffness, and broad chemical resistance. PPS, in similar fashion, has outstanding chemical resistance as well as thermal and dimensional stability. Seals in the DV are typically Buna, but FKM, silicone, and EPDM are available on request.

The valve has rather large flow passages and is quite dirt tolerant, says McBreen. It runs fine on air filtered to 40 μm and offers an important user-friendly feature: the valve is easy to disassemble and clean.

Control voltages are typically 12 and 24 Vdc, but many users design their own circuitry. One example is hit/hold actuation which energizes the valve momentarily with its rated voltage, and then reduces it by approximately 33% to hold the valve position. Some even run off rectified alternating current. Rated power consumption is 1.9 W.

Both manifold and cartridge mounting options are offered, and the valve has #10-32 ports and a 0.75-in. body. �ǳ�web is also producing a metric version for marketing worldwide. It has M5 ports and a 19-mm body.

Markets & Applications
DV valves are suitable for many applications across a diverse range of industries. "We feel it's a very optimized valve," stresses McBreen. "It has a small package, with little heat rise, and low power consumption. They mount on three-quarter-inch centers, can flow a lot of air, and they're very price competitive."

He ticks off a list of potential applications, such as in medical devices like blood-pressure cuffs, for analytical instrumentation, gas chromatography, and leak-decay test systems. In manufacturing settings, banks of valves are well suited for controlling production machines and packaging operations—applications that tend to have lots of cylinders and actuators.

A fully ported three-way version of the DV is slated for introduction this fall, and a proportional valve is in the works.

Tags:

Electronic Valve Series Flow Chart

Rachel Desenberg — Tue, 08 Jan 2013 16:22:36 +0000

Category:

Product Information

�ǳ�web Electronic Valve Series Flow Chart

Note: Add "A-" prefix to any �ǳ�web EC, ET, EV or EW standard series electronic valves where an Analytical version is available.
(Example: A-ET-2-12-L)

Click here for more information on �ǳ�web Electronic Valves

Electrical Specifications
Nominal				Power (watts)	Working Range (cont. duty)
Series	Voltage	Current (amps)	Resistance (ohms)
• Standard • Oxygen Clean • Analytical	6	0.11	54	0.67	90 to 150% of rated voltage
	12	0.055	218
	24	0.028	864
• Corrosion-Resistant	12	0.098	122	1.2	90 to 110% of rated voltage
	24	0.049	486
• EM Series • ES Series	12	0.083	144	1.0	90 to 120% of rated voltage
	24	0.042	576

Tags:

electronic valve

�ǳ�web Oxygen Clean Manifolds Ideal for Sensitive Environments

Chris Agricola — Fri, 28 Oct 2011 15:36:06 +0000

Category:

Advertising

Single- and multi-station manifolds are available for use with �ǳ�web’s Oxygen Clean series electronic flow control valves. These manifolds offer either single- or double-sided mounting in Oxygen-compatible electroless nickel plated brass material, and feature 1/8” NPT input ports and #10-32 outlets.

The Oxygen series pneumatic valves utilize a unique patented valve system that has been used and proven throughout many industries. With a low power consumption of only 0.67 watts, a response time of 5 to10 milliseconds, and voltages of 6, 12, or 24 volt DC, these new valves offer unlimited flexibility in design.

All �ǳ�web Oxygen clean products are manufactured and assembled for applications in Oxygen-enriched environments that are extremely sensitive to contamination. They are ultrasonically cleaned and inspected in an enclosed controlled area with a state-of-the-art positive pressure High Efficiency Particulate Air (HEPA) filtration system. In addition, both organic and inorganic contaminants such as particulate matter and Hydrocarbon oils are removed.

Available in 1- through 12-stations, these new manifolds provide easy access for grouping valves, fittings or other pneumatic components. For more information about these manifolds or any of �ǳ�web’s 5,000 other pneumatic products, call 877-245-6247. www.clippard.com/oxygen

Tags: