Processing

Tech Update: Valves

May 3, 2012
KEYWORDS actuators / CIP / valves
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Valves are like electrical outlets in a food plant: They’re everywhere, and little attention is paid to them until they fail to deliver as expected.

But the underappreciated family of valves—and it is an extended family, with branches in every corner of a production facility—is undergoing a transition. The highest profile change is in mix-proof dairy valves, where the stream of certified continuous-process units continues to flow. Of more general interest is the improved control, networking and monitoring of valve functionality.

Actuator optimization helped reduce product losses during changeovers involving aseptic processing equipment from Tetra Pak Inc., for example. Jean-Pierre Berlan, vice president of sales in the firm’s Toronto office, explains: “When flushing the lines with water, there is inevitably an amount of product that gets diluted and that is not up to spec to be packed. By using the right way to introduce the water, by using the right instruments and having the valves actuated properly, the losses can be reduced significantly.” He cites the example of a manufacturer that was losing as much as 300 gallons of product with each changeover. By overhauling the actuators and making other improvements, losses were reduced by a factor of six, to below 50 gallons.

Advances in controls technology have impacted process and utility valves more than any other factor. Size reduction is the most obvious change. As with other electronics, physical dimensions are shrinking while functionality increases. “The space underneath a tank is limited,” points out Jurgen Henke, marketing manager for GEA Tuchenhagen, Buchen, Germany. “If you can reduce the space needed even a little bit, you are a hero.”

The bigger the plant, the greater the number of valves, making these essential devices a major argument for automated controls. More than 100 Fisher and Baumann control valves, plus another 950 simple valves outfitted with El-O-Matic actuators, were incorporated into a canola oil processing plant built by Bunge in Poland a few years ago. The facility quickly established itself as Bunge’s most efficient plant, with double the production capacity of the facility it replaced. The controls architecture was done by Emerson Process Management, which used wireless positioners for many of the valves and now supports the plant with mobile diagnostic tools to verify open valves are, indeed, open.

Multi-tasking in dairies

The double block-and-bleed mix-proof valve with a control top is the most advanced manifestation of valve technology, and brewers, soft-drink manufacturers and other liquids processors have enjoyed the benefits of those devices for decades. Dairy processing always was the most promising application, however, and until recent years, those operators were precluded from exploiting the technology’s full potential.

That began to change in 2007 when changes to the Pasteurized Milk Ordinance (PMO) allowed processors to run CIP fluid through one side of the valve while milk or other process fluids ran through the other. The change meant that valve clusters that used to be shut down for hours while any of the tanks they were tied to were being cleaned no longer had to stand idle. The PMO amendment was particularly timely for large dairies that faced higher throughput requirements because of consolidations that shuttered older dairies and shifted production to more productive plants.

But to satisfy the letter of the law, simultaneous cleaning and processing could not be done unless the valves were validated to meet revised 3A sanitary standards, in particular 85-01 and, more recently, 85-02. The standards require valve suppliers to validate zero pressure exists in the atmospheric break and zero impingement occurs on the process valve while the CIP seat valve is in the up position for cleaning. Demonstrating this functionality to independent auditors was a challenge that was met, as evidenced by the stream of 3A-certified mix-proof valves now entering the market.

The first was the 365it from Rockford, IL-based Südmo North America Inc., though the valve’s dimensions trended toward cumbersome. The problem, according to Jeremy Hauser, Südmo’s technical manager, was that the PMO required a vent or drain port with the same diameter as the incoming line. For a six-in. valve, that meant a six-in. port, which also meant larger manifolds, more CIP solution and bigger maintenance challenges. Südmo was able to demonstrate that the 100 percent-open requirement was overkill, and last year, the firm received 3A certification for the more compact 365it Complete.

Retooling for the sleeker design coincided with an upgrade of the valve’s controls, which now carry an IP69K rating. The newer controls stand up to high-pressure and high-temperature washdown, explains Hauser, an improvement over the IP65 and IP67 ratings of the previous generation of controls. They also are safety certified as explosion proof, with no possibility of igniting dust in a confined space. Instead of placing a prox switch on the open/close position, the newer control top has a single push button. “The valve teaches itself,” he adds. “There is no variability.”

Alfa Laval Inc. also worked its way through the 3A certification process, with tank valves the most recent devices to pass muster a year and a half ago. The workhorses in the Unique PMO Plus family of mix-proof valves are little changed since 1999, according to Jim Larsen, business development-valves in the company’s Kenosha, WI office. “Single-seat separation of enemy fluids already existed, but capturing the [conformance] data was a challenge,” he says. The certification protocol involved drilling one-sixteenth inch holes in precise locations in the vent area to verify the absence of pressure from cleaning fluids on one side and the process fluid port on the other.

While certification is important from a regulatory perspective, a more meaningful advantage of Alfa Laval’s valves is the modest amount of compressed air and CIP fluid they consume. “Our actuator cavities are as small as possible to perform the functions,” such as lifting the valve seat, says Larsen. Getting manufacturers to focus on reduced air consumption is difficult, but saving CIP fluid by accelerating the opening and closing of valves during cleaning gets people’s attention. “It can take up to five or six seconds in some cases for seat lifts with some actuators,” Larsen maintains. The Alfa Laval units execute the function in half a second. Charged CIP fluid is not cheap, and faster closing of a valve means a lot less fluid going to drain.

Flat valve society

PMO and aseptic processing aside, sanitary design always is a consideration in flow technology. “Hygiene regulations are getting higher and higher,” Tuchenhagen’s Henke observes, and the sealing technology and materials of construction for bellows and other components are improving to keep pace. GEA has three in-house engineering divisions to serve the needs of dairy and food, beverages and beer, and pharmaceutical systems. The valves and other components specified by the engineers in those divisions are dictated by the criticality of hygienic design for the manufacturer. For example, the planar surface of a pharmaceutical valve is significantly flatter than a food valve’s because of the premium placed on the elimination of bacterial harborage points, though the differences are microscopic and measured in microns.

That said, some food companies are gravitating toward valves originally engineered for pharmaceutical production. A case in point is Tuchenhagen’s Vesta sterile valves. The valves can replace any diaphragm valve. The key is the design of the bellows, which feature a metal-to-metal stop that prevents premature wear. Citing the example of a manufacturer that was replacing the bellows of a diaphragm valve every few months, Tuchenhagen’s Larry Harper maintains the Vesta valve that replaced it has gone through 3.5 million cycles without a change. “They might change their PM spec to five years,” says the business development manager-Vesta valves for Tuchenhagen’s North American division, which is based in Portland, ME.

However, bellow valves are not suitable for aseptic processes involving fibrous products. To address those applications, UK-based APV developed the Delta MS4/MSP4 series with a single-layer PTFE diaphragm. Depending on the size, the valves can handle operating pressures of up to 10 bar (145psi).

APV was acquired four years ago by SPX Corp., adding the valve supplier for dairy processors and others to a portfolio that already included Waukesha Cherry-Burrell (WCB), Delevan, WI. While the acquisition gave SPX two complementary brands, it also presented management with an opportunity to mix and match their respective strengths. The first hybrid valve out of the block is the WCB ball valve, with more set to debut later this year.

The ball valve features an APV actuator that replaces a rack-and-pinion actuator engineered by WCB, according to Chris Sinutko, a product sales specialist at SPX Flow Technology. In addition to being more economical, the change accommodates a standard control top mounting, thereby simplifying the user’s need for replacement parts.

Open-standard communication cards are supported by SPX’s newest generation of control tops, Sinutko adds, and the precision of SPX’s electromagnetic positioners that sit on top of the actuators result in better control of flow rates. Much of the mystery surrounding the programming of those controls has been eliminated, as SPX strides to deliver more robust, goof-proof valve controls.

Yet, sophisticated electronics and advanced automation aren’t for everyone, and the butterfly valve likely will remain a fixture in manufacturing for generations to come. Secure separation of dissimilar fluid streams is desirable for slower-paced processes, as well as high-volume dairies. The Spanish firm Inoxpa addresses this need with its new double-butterfly valve.

The company’s US subsidiary is based in Santa Rosa, in the heart of the California winemaking region. Winemaking can include considerable downtime, points out Lluis Busquets I Pujadas, head of Inoxpa’s technical department, and manually operated valves are the rule of thumb for small to mid-sized winemakers. The LBV (leakage butterfly valve) operates with a single actuator and a chamber between the valves. The chamber is under atmospheric pressure and opens to the exterior. A failure in either of the two gaskets results in leakage, providing a visible sign of valve failure.

Fail-safe devices, improved hygiene and greater precision, whether manual or aided by electronics, characterize the current state of valve technology. The devices themselves serve simple functions: on, off or some point in between. By continuously refining their performance, valve engineers aim to keep them, if not out of sight, at least out of mind. 

 

For more information:

Jim Larsen, Alfa Laval, 262-605-2623, jim.larsen@alfalaval.com

Jurgen Henke, GEA Tuchenhagen GmbH, 49-4155 49 2242,
juergen.r.henke@geagroup.com

Lluis Busquets I Pujadas, Inoxpa SA, 34-972 57 52 00

Chris Sinutko, SPX Inc., 262-728-4684

Jeremy Hauser, Südmo North America, 815-639-0322, jeremy.hauser@pentair.com

Jean-Pierre Berlan, Tetra Pak Inc., 905-780-4986, jeanpierre.berlan@tetrapak.com

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