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Hygienic Design for Processing Equipment
by F. Tracy Schonrock
In the more than 40 years that I have inspected processing facilities and evaluated equipment design, I have found an alarming number of equipment buyers and users that equate the mere shininess of stainless steel as hygienic. Stainless steel and other noncorrosive materials are, of course, important but the hygienic aspects of the equipment come from the details of the design. The basics of hygienic design are universal. It does not matter if you are processing dairy products, meat products, fruits, bakery products, or any other of the myriad of food products manufactured, the basics are the same. There may be differences in the details of materials or design features of construction to accommodate a specific product or process, but the overall principles won’t change. As the saying goes, “The devil is in the details.” And the devil is the potential for contamination and loss of customer trust.
There are a number of false perceptions about hygienic design and hygienic processing, such as the following.
There are levels of cleanliness. This is false. Clean is like being pregnant; you either are or you’re not. There are, however, levels of soiling that you have to consider as acceptable for your particular process. These may vary from the very slightly soiled, moderately soiled, heavily soiled, to call out the hazmat crew.
Hygienic design costs more. In the short run this is often true for some equipment. The materials of construction, often stainless steel, and the design details increase the initial, up-front cost. The long-term benefits of hygienic design over the life of the equipment will reduce the overall operating costs. Often run times can be extended, cleaning times shortened, cleaning chemical and water usage reduced, maintenance costs lowered, and a longer life of the equipment can reduce return on investment. When you purchase less expensive non-hygienically designed equipment, the old adage “You get what you pay for” applies.
Hygienic design is bad, complicated engineering. This is false. Hygienic design when applied from the very first steps of the design process is very good engineering. Hygienic features such as the removal of cracks and crevices to eliminate microbiological contamination also reduce such engineering problems as stress and crevice corrosion. Proper selection of materials of construction can reduce the potential for pitting of surfaces and galvanic interactions between dissimilar materials. Ease of disassembly for sanitation purposes is also ease of disassembly for maintenance personnel, reducing downtime.
We can modify existing designs in-house to be just as hygienic. In theory this is true. Any design can be retrofitted to eliminate the hygienic hazard issues. It’s just a matter of time and money—lots of time and lots of money. The end cost of retrofitting is routinely significantly higher than the purchase of new hygienically designed equipment.
I don’t have anyone on staff that can truly evaluate a new purchase for sanitary design. You’re in luck; the lion’s share of this has been done for you and is already available in the market place.
Standards in Place
The hygienic standards writing organization for dairy and food processing equipment is 3-A Sanitary Standards Inc. Its Standards and Accepted Practices are recognized internationally. During the 1920s, the need for more stringent and uniform standards for dairy processing equipment became evident as the U.S. economy and consumers entered the modern era. Representatives of three interest groups—processors, regulatory sanitarians, and equipment fabricators—saw the need for cooperative action and introduced the first industry standards for equipment. These standards became known as 3-A standards for the three interest groups that forged a common commitment to improving equipment design and sanitation. Unlike other types of standards, 3-A Sanitary Standards relate to the cleanability of dairy equipment.
In 1944, the U.S. Public Health Service offered full cooperation with the 3-A program, which marked the beginning of a program to provide uniform equipment standards for the protection of public health. This integral participation of the regulatory sector of the industry has become important as the food industry complies with the requirements of the Food Safety Modernization Act (FSMA). Under FSMA, the industry must be able to demonstrate and document that they have implemented the necessary steps to assure the wholesomeness of the products they produce and the effectiveness of the cleaning and sanitation programs they employ. 3-A Sanitary Standards’ involvement directly benefits the equipment fabricator and the processor through the routine acceptance of the equipment during regulatory inspections.
Today there are 68 3-A Sanitary Standards and nine 3-A Accepted Practices. These documents cover a wide range of the basic equipment used in most food processing applications such as pumps, valves, sensors, heat exchangers, and vessels. There are also standards for specialized equipment for packaging, drying, conveying products, etc. A particular piece of equipment can demonstrate that it has been evaluated by a third-party evaluation and conforms to the hygienic standard requirements with the display of the 3-A symbol.
Over decades of collaboration and recognition among the key stakeholders, the 3-A brand has attained wide recognition in the marketplace for food processing equipment and special stature built on a strong foundation of the following elements: trust, independence, and expertise.
From the Design Up
Food processors continuously look for the holy grail of increased production, reduced cleaning time, and reduction of costs. These are the areas in which hygienic standards excel. It is desirable to be able to clean the equipment fully assembled or with a minimum of disassembly, and subsequent reassembly; clean-in-place or CIP as it is known in the industry. This is not as simple as just attaching a spray device and a solution return line to the piece of equipment. Even as basic a piece of equipment as a storage vessel with an agitator requires specific engineering to effectively and safely clean fully assembled. Saying that CIP is possible in a sales brochure does not necessarily make it so.
Hygienic design starts with the very first lines drawn on a blueprint. The first task of the designer is to determine what is to be considered a product contact surface in order to assure that the design will fully protect the product from contamination. In hygienic design, a product contact surface is defined as, “All surfaces which are exposed to the product and from which splashed product, liquids, or soil may drain, drop, diffuse, or be drawn into the product or onto surfaces that come into contact with product surfaces of packaging materials.” This definition directs the designer to consider all of those areas of the equipment, which may be over exposed product or open containers in filling machines.
The possibility for successful CIP cleaning has to begin with the basic concept designs as the equipment develops. Every aspect of the design has to be evaluated through the filter of CIP. The concept of the elimination of creaks and crevices must be paramount. Any surface that is exposed to product must also be exposed to the cleaning and sanitizing solutions. Not only exposed, but with sufficient tolerances so that the cleaning solutions can freely circulate to dislodge and flush away product residues. This leads the designer to consider the proper placement of gaskets and seals, the elimination of dead ends where product residues cannot be removed during either processing or cleaning, selection of a cleanable surface texture, selection of materials that will withstand the chemicals and temperatures encountered during processing, cleaning and sanitization, and the inclusion of a proper slope and drainage of the equipment. This list of design considerations increases as the sophistication of the equipment increases. Inclusion of spray cleaning devices opens up design consideration for flow patterns, component placement to eliminate the possibility of shadow areas that will not be properly treated. The attachment of appurtenances, such as valves and sensors and personal access ports, raise more issues that the designer must consider to assure cleanability, as well as the inspectability of the interior product contact surfaces. No matter how efficient a cleaning system is designed, the surfaces have to be inspected periodically. Inspectability and access to the product contact surfaces is a must for assuring continuing cleaning success.
If you want to gain the most efficiency as possible for production and cleaning while increasing your operational cost, equipment boasting hygienic design standards can be a significant benefit.
Schonrock is a consultant and member of the 3A SSI Board of Directors. Reach him at firstname.lastname@example.org.