Valves work behind the scenes in a plant and are often overlooked until something goes wrong. Yet many new supporting technologies-materials, sensors, actuators and controls-let valves play a major role in fine-tuning a process, decreasing energy usage, improving food safety and protecting employees.
While most of this article will deal with aseptic valves, there are also issues with valves that handle plant utilities such as steam, hot water, glycol or ammonia. Charles (Chuck) O’Donnell, Emerson Process Management’s marketing manager for Bauman Valves, points out a few. Because sustainability and energy issues are crucial, utility valves must have reduced variability and support longer times between maintenance, and they must control close to set point so they don’t waste energy. It’s also important for processors to develop predictive maintenance programs and monitor valves to catch problems before they become serious or waste energy.
Control valves can be a hidden source of wasted energy if they don’t control well, adds O’Donnell. For example, if hot and cold water are being combined to hold a certain temperature and the control valve does not hold its set point properly, the hot and cold water valves will put in too much or too little of each. It costs money to heat the water (or steam), and that expense is being wasted as valves fight each other.
“Valves for steam and plant water often are used to interface with hygienic processing systems,” adds Aseptomag CEO Patrik Denoth. These valves must also meet strict regulatory criteria, and therefore, it is quite common to utilize hygienic or sanitary valves in these duties. It is also important to provide back-flow prevention in order to prevent process fluids from contaminating water supplies, says Denoth.
Food safety firstIn the US, major sanitary standards include the Pasteurized Milk Ordinance (PMO), 3-A Sanitary Standards Inc. and ASME-BPE (Bio Processing Equipment), the last of which drives valve designs primarily for the life sciences industry, says O’Donnell. The PMO standard was designed specifically for dairy applications. FDA typically regulates the elastomers used inside valves that come in contact with food, whereas 3-A regulates design specifics such as food contact areas that must be polished to 30 micro-inches. Also, he says, valves must drain from inlet to outlet, and there must be no places within the valve or piping where cleaning fluids or products collect. If particles collect in a crevice, it’s a perfect breeding place for bacteria.
According to GEA Tuchenhagen NA President David Medlar, the 3-A standards have been “self-certifying.” That is, manufacturers read the relevant 3-A standard and design it so the product standard is met. These include architectural design and physical, metallurgical and materials standards. More recently, independent conformance evaluators visit valve manufacturers, look at the drawings and approve them.
Today, the European Hygienic Engineering & Design Group (EHEDG) is fast becoming the worldwide de facto standard, and according to Tyco Flow Control Industry Marketing Manager Paul Lopez II, a few 3-A members are investigating some EHEDG concepts and would like to see 3-A adopt some EHEDG rules. EHEDG differs from 3-A in that it goes beyond meeting 3-A’s architectural/design specifications; it looks at the performance issues. For example, third-party EHEDG testers take a particular supplier’s valve and put it into a closed loop to test it. With the valve in place, the examiner runs a preliminary CIP step to ensure that all equipment in the loop begins at the same basis point. Then a known type of bacteria is introduced into the system so that it circulates around the loop. After going through a sequence of tests, the system is flushed and rinsed. The valve is then removed from the pipeline, and both are incubated for a period of time to grow any remaining bacteria left after the cleaning stages. As long as the bacteria count inside the valve is no higher than the associated inside diameter of the pipe, the valve passes the test, says Lopez.
According to Knuth Lorenzen, EHEDG president and 3-A steering committee member, EHEDG certifies equipment by doing a visual check like 3-A, but in addition, expands testing to include cleanability, sterilizability and bacteria tightness. Tests are conducted at EHEDG-authorized and accredited facilities.
EHEDG began in 1989 to fill existing gaps of practical guidelines; prepare scientific and technically oriented state-of-the-art guidelines to comply with EU legislation; strengthen the participation with standardization bodies like DIN, CEN, ISO, 3-A, NSF, JIS, etc; and strengthen cooperation with the EU, i.e., food contact material directive, BAT, traceability and other EU projects.
Mix-proof valvesToday, many food makers demand continuous processing. For example, StockPot Soup (Everett, WA) continuously produces soup and sends it to filling lines, thanks to an automated CIP system and mix-proof valves (see FE, December 2008). Whether it’s dairy, soup, beer or sauce, continuous processing requires automating cleaning as much as possible, and automated CIP systems allow cleaning of process piping without disrupting the process. However, this requires a special arrangement of valving and piping.
When liquid coffee concentrate maker Douwe Egberts was looking for leak-proof performance, sterile operation capabilities and long production runs, it chose a routing matrix of 550 double-seated Tyco Varioflow mix-proof diverter valves to ensure process lines could operate in tandem with cleaning lines, reducing plant downtime and costs. The automation of the diverter valves was supplied in conjunction with an intelligent control system for integration into the plant’s PLC system.
According to Gabe Miller, Sani-Matic business development manager, mix-proof valves are becoming prevalent because they allow CIP and processing simultaneously, while providing an atmospheric air break between the processes.
“Clean in place has been around for many years now,” says Jeremy Hauser, Südmo North America, Inc. technical manager. “For [CIP] I see the biggest opportunities in helping [processors] apply the proper valves to their process and assisting them to make sure the valves are installed and used correctly.”
When the PMO regulation was changed in 2007, allowing dairy processors to clean mix-proof valves while product is on one side and cleaning solution on the other, Norit Südmo re-engineered its dairy mix-proof valve to ensure there is no direct impingement or pressure buildup of the CIP solution on the opposite seat. According to Hauser, prior to 2007, PMO mix-proof valves required that seat cleaning with seat lifting be done without the possibility of product in the opposite pipeline. To meet this requirement, dairies shut down lines to clean, losing production hours every day. The new design allows for continuous operation-cleaning in one set of lines with product in the other.
With mix-proof valves, says Medlar, in between the two seats there is a vent, isolation or leakage cavity-all three terms mean the same thing. The cavity is open to atmosphere and open to drain. “If you are walking by the valve and see a leak, it doesn’t mean that you have cleaning liquid leaking into your milk or beer,” says Medlar. It means one of the gaskets or one of the seats is beginning to leak or has failed. When the valve fails in one of these ways, the valve fails “safe.” While the liquids won’t be mixed together, the gaskets should be changed when there is time.
Gasket lifetimes vary according to application, says Medlar. Factors that affect gasket life include cleaning regime, the product itself and how often the valve is switching. Cleaning temperatures, thermal shock and chemicals, as well as whether the product has particulates or is sticky, can degrade gasket life. Gaskets tend to pit after some time, so they should be checked at regular intervals-before a major event occurs. Medlar says that with metal-to-metal seals, gaskets and O-rings are kept to a minimal size, lengthening time between repairs.
To further reduce the possibility of impingement from CIP solutions on the opposite seat during seat lift cleaning, Medlar says his company uses simple geometry to generate a natural vacuum in its new 24/7 PMO tank valve. The valve, completely drainable in horizontal and upside-down positions, lets users keep product flowing while cleaning is being done.
Leaks: Good or bad?When a mix-proof valve appears to leak, is it broken or is it normal operation, with cleaning fluid leaving the discharge port? Stuart Baird, Tyco Flow Control general manager in New Zealand, says that in many cases mix-proof valves are put together in manifolds where 20 or 30 valves are in a tight cluster, and they’re often located in remote parts of the plant where workers don’t often visit. If a technician or operator walks past and sees a leak, he or she will have to contact the control room to have someone operate the specific valve in question.
Tyco’s solution to this problem, says Baird, is to place a patented leak detector under each valve, and have it verify if there is fluid escaping. When the detector is coordinated with software in the control room, engineers can easily determine if the valve is discharging cleaning fluid when it’s supposed to be (for example, during a seat lift) or leaking product when it shouldn’t.
As the call for increased food safety standards continues and food and beverage manufacturers maximize product output, flow control manufacturers must provide technology advancements to protect that balance. Valve performance feedback will ultimately save food and beverage manufacturers money through decreased product loss due to contamination and minimizing maintenance costs by making repairs only on valves that need it.
Other internal improvementsWhile overall valve technology hasn’t seen earth-shattering architectural changes over the last few years, small innovations-often suggested by end-users- add up to big improvements. For example, Denoth points out that position sensors, which provide open-close feedback to the plant’s PLC, have been totally enclosed and located in the control top (Aseptop®) to prevent damage and undesired impacts.
Products that crystallize, or go through a valve at temperatures up to 320°F and high pressures, can pose problems with aseptic valves, says Hauser. A few solutions help processors with these issues. Norit Südmo’s P3 seal technology for its single-seal valve is highly resistant to aggressive chemicals, withstands temperatures up to 320
Controls a necessityWhether or not a processor takes advantage of process information and/or controls, EHEDG does require some monitoring. According to Lorenzen, the EHEDG Design Criteria state that all mix-proof valves shall be equipped with a sensitive electronic information system to present information on the position of the valve. If a leak on the valve appears, based on a damaged seal, it should not result in any cross-contamination of the product.
Today, most of Hauser’s customers require automation of the valve system to maximize processing time and reduce the possibility of mistakes. This means using a control top that houses feedback and the solenoids required to actuate and monitor the valves. Hauser says the use of bus systems can greatly eliminate wiring, quicken startup time and gain more operational tools.
“Automatic valves (pneumatic valves) controlled from a central hub or PLC give unprecedented control and versatility to a plant’s processing capabilities,” adds Denoth. “The feedback and control technology allows processors to minimize downtime and coordinate production and cleaning cycles in the plant.”
According to Medlar, the mix-proof manifold is the heart of the system to route liquids from one set of sources to one set of destinations. In the old days and up until very recently in the dairy industry and in some breweries, cleaning was done manually with hoses and flow plates. A mix-proof manifold allows the connections to be done in hard piping.
But it makes no sense to spend all that money and put in all these valves unless you automate, says Medlar. The ideal is to eliminate manual intervention, the downtime between physically connecting one vessel to a line with a hose or a flow plate, which takes time and shuts down productive work during cleaning. In addition, Medlar says, potentially costly mistakes-like someone getting sprayed with caustic when water was assumed to be in the line-can be reduced.
Without feedback, there can be no control. Lopez says the leak detector can actually provide some solid feedback on a skid, for instance, real-time repair information and valve performance. Over a period of time, processors can begin to see a sequence or pattern that is unique to the skid where the valve is located and put together maintenance programs based on that information.
“Knowing that a failure could happen in the near future so that plant operators can plan a maintenance session between production runs is important,” says O’Donnell. Predictive intelligence is becoming crucial, but requires a control architecture that supports it. O’Donnell says that digital valve controllers must provide real-time feedback about valves’ health and their operating status. A control architecture such as PlantWeb® can monitor valves, transmitters, motors, drives, etc. and feed back critical information to the operators and/or control room indicating any equipment degradation.
The price of automationCan you afford automation? “That’s a good question,” says Lopez. “In some cases, processors find that they can’t afford not to do automation.” Personnel safety is just as important as food safety. With manual switching of hoses and pipes, workers can accidentally come into contact with caustics and acids. And, if employees are wearing heavy gloves, they may be unaware of a hot water hose until it’s too late.
The economics of automation, says Lopez, may not be pressing if a processor has a simple operation-such as one tank, one process, one product. But as the process becomes more complicated-say, three tanks, three processes, three or more products-the case for a continuously automated process with CIP becomes more convincing.
According to Lopez, the misleading reputation that mix-proof technology is too expensive should be overcome. “The mix-proof manufacturers have proven that these systems are worth their weight in gold when applied properly.”
He adds, “Advancements in automation and mix-proof technology have only strengthened the argument why food and beverage manufactures should take the next step."
For more information:
Charles O’Donnell, Emerson Process Management, 603-766-8500,
Gabe Miller, Sani-Matic, Inc., 608-226-857, firstname.lastname@example.org
Herbert Timmermann, APV, (49) 2303-1080, email@example.com
Paul Lopez, Tyco Flow Control, 717-314-1129, firstname.lastname@example.org
Stuart Baird, Tyco Flow Control, 64 9 921-7221, email@example.com
Jeremy Hauser, Südmo North America Inc., 815-639-0322, firstname.lastname@example.org
David Medlar, GEA Tuchenhagen North America, 410-707-7608, email@example.com
Jim Larsen, Alfa Laval Inc., 262-605-2623, firstname.lastname@example.org
Patrik Denoth, Aseptomag, 815-633-8411, email@example.com
Knuth Lorenzen, EHEDG, 49 4155 49 2427, firstname.lastname@example.org