�ǳ�web Knowledgebase - high flow valve

High Flow in a Miniature Package: �ǳ�web's DV Series

Rachel Desenberg — Thu, 09 Jun 2016 19:04:54 +0000

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�ǳ�web's entry into the miniature electronic valve market began in 1973, when Leonard �ǳ�web, founder, introduced the EV line of valves that utilized only one moving part, the "spider." Today, the EV valve is still serving a very horizontal market with thousands of installed applications in a multitude of industries. Since the initial introduction, several new series have been added to the line, including; Corrosion-Resistant, Oxygen Clean, Analytical, ECN, EVN, ETN, Proportional Control, Intrinsically Safe, EM and ES series, all which utilize the "spider" design. Enter the new DV Valve.

New Design Challenges

According to Dave McBreen, the DV valve project design engineer at �ǳ�web, the all-new design began with the coil. "It's not that we designed the valve around the coil," said Dave, "but we knew our design parameters called for the coil to be less than 2.0 W, so we began there. The 2.0 W would allow us to see what kind of magnetic pull we could generate." McBreen goes on to say that many coils were made in the attempt to optimize one. This led to an optimized solenoid needed for the valve. The process for determining the correct coil was enhanced by a coil calculator. The calculator, which was designed by �ǳ�web's engineering department, greatly reduced the design time and provided the exact specifications of the coil.

Once he had the design criteria, McBreen felt that his biggest challenge was to consider the manufacturing processes needed to get the product out the door—how to get a cost effective, optimized design through manufacturing and yet be fairly simple to assemble was the challenge. Included in this thought process was the concern with size limitations; the valve needed to be small. Yet, he had other criteria to consider, including power, flow, pressure, and materials.

The requirement from the very beginning called for all metal parts to be stainless steel with the nozzle and bobbin utilizing certain plastics that would allow for FDA approval. The all-stainless housing provides many environmental advantages and is manufactured in three Mary Gannon, Design World Senior Editor parts. McBreen is very enthused about the three-part design and just what a "robust package" it delivers. "It can be taken apart and put back together in seconds," said McBreen. One of the main reasons for this is that the valve only has one moving part—the "spider."

The all-new spider, designed from stainless steel, is capable of flows to 100 lpm at 100 psig. Although this is a new spider design, compared to the existing EV line, it is still a poppet valve. With a preload of approximately 0.017 in., stroke up to 0.018 in., and response time of 10-15 msec, the DV Series can be utilized in many applications. And, with the over-molded seal, the DV Series will continue the high standard set by the industry-leading EV line for leak-free operation, which is particularly meaningful for analytical applications.

McBreen also noted that, "in addition to being very economical to produce, the straight-forward, robust design leads to a hassle-free assembly. The new valve has another feature not readily found in other miniature valves: bidirectional flow. It is designed to serve as a dual flow valve within a certain pressure range. Applications requiring this feature should be discussed with �ǳ�web's technical staff prior to installation."

Manufacturing begins

After two years of building prototypes and testing (using FEA stress analysis on the spider and magnetic analysis software for the valve) it is now ready for market, according to McBreen. Initially the product will be offered with an orifice of 0.052 or 0.070 in., with manifold or cartridge style mounts, and voltages in 12 and 24 VDC. Air and other compatible gases are the recommended media with the standard seal but other seals are available for use with other medias. Simply changing the coil, nozzle orifice or mounting options helps to enable special customer applications.

The DV line will be assembled in �ǳ�web's Fairfield, Ohio plant along with the EV line and other Minimatic electronic valves where, according to Steve Schutte, Plant Manager, "all work cells and personnel are prepared for a very positive response to this new product. The ability to produce thousands of valves per week is due in no small part to the straightforward design, which means a straightforward assembly. In addition, an automatic tester is in place which ensures 100% of the valves will go through the testing process." He also noted the testing equipment was designed and built by �ǳ�web.

Application potential

Now that the design and manufacturing processes have been finalized, where will the valve be used? According to Rob �ǳ�web, Vice President Sales & Marketing at �ǳ�web, "one of the key applications will be in the medical field. Although there are numerous applications within the medical industry, none will be more applicable for this valve than blood pressure cuffs. Additionally, applications requiring some sort of pressure monitoring, pulse monitoring of the heart or perhaps oxygen therapy have a great amount of potential. With its high flow capability, respirator applications will definitely be one of the most common uses. Other applications in the medical field would include ventilator and kidney dialysis machines."

While medical will be a primary market, according to Rob, there are many other applications and markets, including gas chromatography, liquid chromatography-mass spectrometry, and other applications requiring analysis. He noted the valves would be used throughout the packaging industry, especially where small banks of manifold mounted valves would be needed.

Future development

So, what's ahead for the DV valve? According to John Campbell, President, "this is one of the new generational valves and we believe it will contribute to the success of the company for a long time. From this basic design we expect to be successful from the start; we'll be growing into many other products as we continue to invest in engineering and continue to believe in new product development as the key to our future."

Original Article, May 2014
By Mary Gannon

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Compact Valves Combine High Flow, Extreme Reliability

Rachel Desenberg — Tue, 10 Mar 2015 18:45:55 +0000

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Original Article, July 2014
By Kenneth Korane

"More with less” is the new mantra for machine builders who rely on pneumatics. In particular, they’re demanding valves that offer ever-higher flow capacities from ever-smaller packages. This lets pneumatic systems do more work without taking up more space.

�ǳ�web Instrument Laboratory, Cincinnati, Ohio, has responded with a new line of two-way solenoid valves called the DV. Its construction builds on technology developed for the company’s workhorse EV valves. But it provides five to six times more flow in an equally compact design, and the valves are built to last 750 million cycles.

Users rely on banks of these valves to handle a variety of tasks, explains �ǳ�web Design Engineer Dave McBreen. Applications include medical devices like blood-pressure cuffs, analytical instrumentation, gas chromatography, and leak-decay test systems. The valves can also control groups of cylinders and actuators in production and packaging machines, where they are tightly packed in multistation manifolds to minimize space requirements. Thus, the DV valve’s OD couldn’t exceed three-quarters of an inch, says McBreen.

The DV comes in both cartridge and manifold-mount versions, with #10-32 or M5 ports.

Engineering software played a major role in the DV’s development. For instance, �ǳ�web engineers had to design a solenoid coil that fit the available envelope and could generate enough power to shift the valve at high pressures. And response time had to be in the 10 to 15-msec range for high-speed operation. Because the engineers faced seemingly endless combinations of design variables—power levels, coil dimensions, wire gauges, and so on — the development team developed a Coil Calculator program that streamlined the design process. The software let them plug in geometry and other parameters and key in on the combinations that generated the best results.

Engineers used the Calculator along with a 3D electromagnetic field simulator program to tweak the resulting magnetic circuit and refine the coil in relatively short order, and with impressive results. The first prototype met all physical requirements and performed to within 5% of predictions, says McBreen.

The next challenge was designing flow passages that increased the valve’s capacity, but not its size. Engineers relied on both computational fluid-dynamics analysis, in this case Flow Simulation CFD from Dassault Systemes SolidWorks, based in Waltham, Mass., and on physical testing of machine prototypes.

CFD proved an excellent tool for modeling flow through individual valves and examining various options, says McBreen. For example, certain nozzle geometries 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 engineering team also made extensive use of SolidWorks FEA tools in designing and analyzing the “spider,” an unusual spring that shifts the valve when the solenoid deenergizes. It measures only 0.020-in. thick by about a half inch in diameter, yet generates sufficiently high force with little movement — the DV has only 0.018 in. of stroke. Minimal stroke is necessary, says McBreen, to ensure precise control and maximum flow at operating frequencies as high as 32 Hz.

An unusual spider spring shifts the valve when the solenoid deenergizes. Working stroke is only 0.018".

Because the valve has several working components and an extremely short stroke, part tolerances could have been an issue. “If you’re not careful, tolerance stack-up will match the stroke and the valve won’t work. The battle is, how to controls those tolerances without driving manufacturing costs through the roof,” states McBreen.

“It gets a little tricky, but there are certain features we can tightly control and eliminate 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 tight tolerances. We have the right equipment, we’ve been doing it for a long time, and it’s less costly that using outside vendors.”

The DV is rated for flow of 100 lpm at 50 psi with a 0.070-in. orifice, and 100 lpm at 100 psi with a 0.052-in. orifice. The valve runs on air filtered to 40 um and is suitable for service with other compatible gases, and it is currently being tested with water. The valve base is made of 303 stainless steel, and other “wetted” materials include polyetherimide (PEI) and polyphenylene sulfide (PPS). Seals in the DV are typically Buna, but FKM, silicone, and EPDM are available on request.Control voltages are typically 12 and 24 VDC, and rated power consumption is 1.9 W.

The DV is a high-flow solenoid valve built to last 750 million cycles.

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 with M5 ports and a 19-mm body. A full ported three-way version of the DV is slated for introduction this fall, and a proportional valve is in the works

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