A clever retort

This case study illustrates how an OEM that builds custom batch sterilizers provides compliance support and reduces development time by 30% with the use of commercial HMI data management.

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 By Tim Schurr, Senior Controls Engineer, Stock America


tock America Inc. is an original equipment manufacturer that builds custom batch sterilizers -- known as retorts, as well as associated equipment for food and pharmaceutical processors. Based in Grafton, Wis., the company works directly with users to design, install and validate in-container sterilization technology that helps ensure products and packaging are contamination free. Stock America serves processors of both retail and institutional products, so its retort designs are standardized, yet flexible enough to meet the varied needs of that diverse customer base.

Stock America develops approximately 30-50 retort units annually, each taking four to six months to build. The units are uniquely designed to support highly sensitive products and containers (See Figure 1). This is a niche market, but it's a growing market.




With 21 CFR Part 11 regulatory requirements, it was increasingly difficult for Stock America to keep up with the rapid technology advances for the custom programming, controllers and other hardware devices required for the operation of the custom batch sterillizers it builds. 

Typically, filled and sealed containers (metal, glass, foil or plastic) are loaded into baskets and conveyed into the retort, where they are sterilized with high-temperature steam or water. In addition to being able to control the use of steam heating and cooling for sterilization, Stock America units also control pressure, temperature, rotary speed and water level. These controls are important for customers with sensitive products that need to meet strict levels of quality and cleanliness such as canned vegetables, specialized coffee drinks, chemicals and pharmaceuticals.

Our Latest Challenge
We had been using proprietary data acquisition and transfer technology for our retorts, developed based on custom Microsoft Visual Basic scripts. Data was captured from the retorts using controllers set up for viewing on an operator interface and transferred to a database. Stock America developed and maintained the software internally, updating the technology based on customer requests or as needed for new functions.

Because the proprietary software was integrated closely with Microsoft programming standards and Allen-Bradley control technologies, changes in those products also prompted regular changes to the software.

Although proprietary software offered most of the functionality Stock America customers needed, new federal regulations for consumer safety and security were introduced to the market, impacting Stock America's large base of food and pharmaceutical customers. The Food and Drug Administration (FDA) began to demand more stringent safety regulations through 21 CFR Part 11--requiring detailed records on how products are designed, manufactured, packaged and sold. As part of a customer's total manufacturing process, data-producing hardware and software components of Stock America retorts would also need to provide compliance records.

Change Is Good
With these new regulatory requirements, it was increasingly difficult for Stock America to keep up with the rapid technology advances of Microsoft for the custom programming, and Rockwell Automation for the controllers and other hardware devices. The company no longer had the time to continually modify the software scripts to stay current, and the staff didn't want the internal development process to slow down time-to-market. In addition, the company's product managers and design engineers wanted to continue to incorporate new functionality and improved security features, but didn't have the time or the resources to do it effectively.

Company engineers decided that it was time to look at replacing its custom Visual Basic scripts with a commercial HMI software package that would provide data acquisition and transfer, with integrated 21 CFR Part 11 compliance capabilities.

"We wanted to find a commercial HMI software package that would let us offer maximum HMI functionality, and reduce the amount of time we were spending in development," says David Polvino, vice president of Stock America. "We felt that being able to off-load development tasks would help us focus on adding new capabilities to the retorts, rather than spend our time just keeping up with the technology."

The Ultimate Solution
The Stock America Sterilization System Division in Cary, N.C., is responsible for engineering and sales support for all Stock America retort systems. The sterilization division evaluated a number of commercial HMI packages and selected Rockwell Software RSView Supervisory Edition HMI package, running on Allen-Bradley VersaView industrial computers (See Figure 2). The decision to go with Rockwell Automation was due to the company's previous experience, familiarity with Rockwell's products, and,critical for Stock America,its support for 21 CFR Part 11 compliance.


A new HMI package offered all the data acquisition functions that Stock America was looking for, adding improved security and reporting, using it primarily to record process temperature and pressure for compliance with governmental regulating agencies.

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