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Choosing the Right Operator Interface System for Meat Processing Environments

Thu, 04/03/2008 - 10:28am
Bill Fleming, STRONGARM Designs

According to the U.S. Department of Agriculture, in 2007 alone there were 16 serious meat recalls involving E. coli contamination, each costing millions of dollars – a sharp increase from 2005 and 2006. This alarming string of recalls has led to the increased scrutiny of meat plants and their equipment.

While HACCP (Hazard Analysis Critical Control Point) and other regulatory guidelines exist to help meat and poultry processors evaluate the overall cleanliness of their facilities, the burden of equipment evaluation falls squarely on the shoulders of the processors themselves. Ceilings, floors, refrigeration systems, electrical systems, conveyer belts, and floor drains are all well-known threats to a plant’s cleanliness, efficiency, and ability to keep up with multiple product lines.

Plant floor Operator Interface Systems (OIS) are a key component in tracking regulatory guidelines and batch control. However, the OIS itself can harbor bacteria if not properly designed.

When evaluating an OIS and other plant equipment, cleanliness should be at the very top of your evaluation criteria. To maximize your investment, your OIS should also provide maximum protection and adaptability to help keep your business on track. Here’s what you need to know to select an OIS that meets all of these criteria.

Cleanliness

Aggressive equipment washdown is an everyday, every-shift, and every-batch occurrence in a meat plant environment, with the use of powerful cleaning agents a frequent part of the routine. Corrosion resistance is critical, so painted surfaces, which can peel and flake, are out. Stainless steel construction is a must. In addition, any OIS used in beef or poultry processing environments should feature the following:

* Minimal crevices. An OIS should be as crevice-free as possible to minimize the accumulation of hidden, hard-to-reach liquids and contaminants. Common areas of concern are around integrated components such as displays, doors and on any joints or seams. One-piece construction and radius corners are commonly utilized to eliminate these crevices.

* Sloped tops. This will prevent stagnant water (which can harbor bacteria and other wastes) from pooling on top of the enclosure.

* Beveled edges. 90 degree edges, particularly around keyboards and displays, can be difficult to clean thoroughly. By providing a beveled edge, the surface becomes easier to clean and eliminates a common area of particulate accumulation.

* Appropriate keyboards and pointers. There are a variety of choices for keyboards and pointers that can be incorporated into an OIS, but keep in mind that some are better suited for cleaning than others. For example, a membrane-style keyboard provides a smooth surface that can be easily wiped down. A rubber keyboard with raised keys, however, is difficult to keep clean and may dry out and crack due to prolonged exposure to harsh cleaning agents.

Protection

Being in an aggressive washdown environment also means that the OIS must be able to protect the interior components from water and solvents. Look for an enclosure with a NEMA 4X rating; this will ensure that the interior is protected from splashing water, water seepage, falling water, severe exterior condensation, and most importantly, from hose-directed water. In addition, an OIS should incorporate the following features:

* Washdown-optimized doors that channel sprayed water away from the interior of the OIS. Simple gasketing may not be enough; over time, repeated exposure to water can degrade the gasket and compromise its integrity. Enclosure doors that will be used in an aggressive washdown environment should incorporate a channeling system that prevents the water from coming in contact with any interior gaskets. By doing so, you will be assured that your OIS will be water-tight not only upon installation, but for many years to come.

* Sealed components. It’s often not enough that the enclosure itself is NEMA 4X rated; any integrated components (including displays, keyboards, and pointers) must be similarly rated. Look for components that are completely sealed and water-tight.

Adaptability

Though most meat processing plants face similar dangers when it comes to plant cleanliness and contamination, the plant floor designs of meat processing facilities can differ substantially. Because of this variability, there is no one-size-fits-all solution when it comes to OIS design. Once upon a time, this may have meant re-engineering the plant floor to accommodate a specific OIS design. Now, however, manufacturers offer a range of stainless-steel OIS designs that can be incorporated virtually anywhere in the plant or process area space. Options include:

* Vertically Adjustable Systems These systems typically provide up to 30” of counterbalanced vertical repositioning with additional rotational articulation. They can be attached to a wall, floor post, ceiling, or machine top.

* Console Systems Low-height console systems are designed to provide improved process visibility.

* On-Wall Stations These systems mount directly to the wall via tabs or holes in the rear of the enclosure. Not only do they save space, but they are very easy to install.

* In-Wall Stations Similar to On-Wall Stations, these units fit into the confines of a shallow wall, minimizing the protrusion into the room. Front door access permits interior access to the internal components without compromising the wall seal.

* Mobile Systems These specially designed systems allow you to bring the operator interface to the process, eliminating the need for multiple fixed stations. Mobile Systems are idea for Bulk Product, Batch Pre-Weigh or QA applications, and can be outfitted with integrated weigh scales, bar code scanners and label printers.

The vertically adjustable OIS is the most accommodating for different-sized operators and precise positioning of the display. It is also ideal for meat processing environments because it can be repositioned during operation, moved over and around obstructions, and deployed in either side of a conveyer belt.

Functionality

A meat plant’s process and/or automation software is a critical element of the plant’s efficiency. Achieving that efficiency, however, depends on the accurate use of that software – and that’s where OIS design comes in. With countless stainless steel configurations available, OIS design has evolved to a place where plant managers are no longer forced to choose cleanliness over user-friendliness. Additionally, increased attention is being paid to the ergonomic design of these systems, from adjustability and articulation to proper display height and keyboard angles.

Consider the following when selecting an OIS:

Keyboards

Membrane mechanical keyswitch keyboards are completely sealed and easily cleanable, making them the preferred choice for harsh chemical environments.

Pointers

A wide variety of pointer options are available to the user, including trackballs, touch pads, and industrial rubber pointers. A recent innovation is the industrial mouse, constructed of stainless steel and NEMA 4X rated. The use of an industrial mouse provides the operator with a familiar pointing device, greatly improving their comfort and efficiency.

PC Location

PCs can be installed within the system itself or in a remote location where it can be easily maintained without having to access the OIS for upgrades (an important consideration in hazardous environments). The PC can be connected to the OIS via a KVM extender and a simple CAT-5 cable, allowing the PC to be located up to 1000 feet away. This also allows the OIS itself to be more compact, and eliminates the need for additional cooling to maintain the proper operating environment for the PC.

Sanitary, Successful Implementation

As meat plant, safety takes center stage in the American conscience; processors must take a close look at the equipment that comes in contact with their products. By selecting an OIS that meet cleanliness, protection, and functionality requirements, processors can increase the safety of their environment and their operations run smoothly.

(The material in this article is intended to familiarize the reader with types of hazardous area problems and solutions but does not present specific instructions and safety code requirements necessary to install a complete instrument system.)

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