Processing Magazine

How to cool down process cooling systems

April 4, 2007

The use of cooling water is prevalent in many manufacturing industries. In fact, cooling water is important in various production processes, whether to chill plastic following heat treating or to cool down vats during chemical processing. As anyone involved in procuring water for these processes knows, the precious liquid is not inexpensive, particularly for those using as much as several thousands of gallons per minute. More costly than the water, however, is the cost of not having the water.

The most probable situation in which a company would not have water is if the company’s process cooling system fails to operate properly or shuts down altogether. Don Rivard, an electrical engineer for Process Cooling Systems, Inc. in Leominister, MA, is painfully aware of the consequences of this scenario. About 12 years ago, Process Cooling customers were, on occasion, actually living that industrial nightmare.

“The transducers we were using in our cooling solutions were not particularly reliable,” recalled Rivard, who handles all aspects of design for the power and control systems of his company’s equipment, including component specification and vendor selection. “Many of them were failing completely or just losing calibration; either way, it often left our customers in a tough spot. The transducers were failing for any number of reasons: excess vibration, water -pressure fluctuation, voltage tolerances, you name it. As a result, they either prohibited our cooling units from delivering proper performance or stopped them from performing completely.”

Given the importance of the transducers to the overall function of the cooling systems ─ which can represent a major capital investment between as high as $1.5 million ─ this was clearly a situation that screamed for remediation. Depending on their design and specific application, over 60% of the systems designed by Process Cooling Systems require the use of a pressure transducer for maintaining constant machine speed and regulating water pressure and flow, all while conserving energy. What’s more, the vast majority of these transducers are not positioned directly on the equipment where they can be safely contained and monitored. Instead, they are mounted on the process piping, where they are exposed to a myriad of harsh ambient conditions.

Based on the non-negotiable need for superior transducer performance, particularly in severe environments, Rivard knew a switch was absolutely necessary. After being dissatisfied with the offerings of three major transducer producers, Rivard heard about Setra Systems, Inc. of Boxborough, MA, a leading designer and manufacturer of pressure, acceleration, and weight sensing devices.

“The primary reason we chose Setra is that their products are reliable, accurate and cost-effective,” said Rivard. “In truth, while the reliability and accuracy are the most critical considerations, they mean nothing without cost efficiency. Other transducers are available that deliver similar performance but with a much higher price tag,” he added. “We’re in a field that is very cost-competitive, where the profit margins are already razor-thin. To protect those margins, and to keep the cost of the systems reasonable for our customers, we need products that are cost-effective. Setra’s ratio of cost to reliability is phenomenal.”

When Process Cooling began using Setra products about a dozen years ago, they started with the Model 206 Gauge Pressure Transducer but soon moved to the Model 256 when it became available (the 256 and 206 are similar, however, the 256 is used in more rugged conditions. Packaged in a die-cast aluminum enclosure specifically designed for NEMA4/IP65 service, the Model 256 incorporates Setra’s patented capacitive design which, coupled with the company’s proprietary circuitry, produces a strong signal that assures customers of superior mechanical and thermal stability as well as accurate output, even through many years of pressure cycling. Rivard is particularly enthusiastic about the wide range of PSI pressures that the Model 256 can accommodate.

“Most of our customers’ needs fall within a PSI pressure of 0-500,” Rivard said. “That’s almost smack in the middle of the Model 256 pressure range, although it can handle ranges of 0-2 on the low end, all the way up 0-10,000 on the high side.”

The environmental data for the Model 256 is equally impressive.

“These transducers retain their accuracy in temperatures as low as -40 degrees F and as high as 260 degrees F,” Rivard said. “This is critical, since the ambient temperatures at our customer’s plants can vary greatly, not only from plant to plant but even within the same plant. And the transducer housing makes it very durable against dust, vapor, and just about anything our customers can throw at it.”

The units designed and created by Process Cooling Systems do not come in a “standard” size or configuration; they are application-dependent. According to Rivard, they can be small enough to fit into a 4 ft. x 4 ft. space or they can be large enough to require several tractor trailers to move. Yet, the Setra devices can be easily incorporated into any of the systems, regardless of size or shape.

“We’ve found that Setra transducers engineer well into any system,” said Rivard. “Of course, since the bulk of the transducers are mounted on outside piping, this is generally a moot point. But even when they are mounted in or on the machine - which is sometimes the case in smaller units - their compact dimensions make it a simple process.”

Currently, Process Cooling purchases about 200 of the Model 256 transducers per year (the company occasionally uses the Model 209 in specialty applications). Rivard says that they hold up day after day, and that problems such as excess vibration, temperature and other ambient factors are concerns that other cooling unit developers might have to worry about  but not Process Cooling.

“These things are no longer a problem for us or our customers,” he said. “Neither is production downtime. Setra solved our reliability issues, and allowed us to do it without having to shoulder a huge financial burden.”