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Tubular Conveying is Not So Obvious Until You Look Inside

February 25, 2019
Cable and chain considered in tubular drag conveyors
Cable and chain considered in tubular drag conveyors

The list of industrial conveyor options is long. Aeromechanical, pneumatic, vacuum, screw auger—all are good choices depending on your application. But, if you’re looking for a gentle, dust-free way to transport your materials, the tubular drag variety is your best bet. Tubular conveyors have moved materials in a safe, clean, and efficient manner for over 50 years. Using both chain and cable systems, they’re ideal for moving delicate bulk materials and mixes through all phases of production and packaging. 

The food processing industry in particular has taken advantage of this system. As their name suggests, tubular conveyors move dry bulk products such as powders, cereals, snack foods, specialty grains, etc. to discharge points in enclosed, dust-free tubes. These prevent foreign substances from contaminating the product while keeping dust from the product itself from escaping into the environment. They also transfer blended materials of different sizes, shapes, and bulk densities without separation.

Product Contamination
Maintaining system sanitation and barring foreign matter from the process stream are critical objectives at every step. However, safety and product reliability issues have been an escalating concern in the food processing sector. More stringent track and trace requirements by the U.S. Food and Drug Administration (FDA) have elevated product safety procedures to eliminate food contamination and cross-contamination of allergens. This is to avoid tragedies like Peanut Corporation of America’s (PCA) 2008 recall, the largest in U.S. history. PCA peanuts contaminated with salmonella were directly tied to nine deaths and more than 700 food-poisoning cases across the country. The recall eventually helped lead to President Barack Obama’s passing of the 2011 Food Safety Modernization Act (FSMA), one of the largest reforms in food safety laws in the last 70 years.

Today’s FDA measures enforce sanitary conditions in processing facilities to ensure safe public consumption. Tubular drag conveyors have proven to be one of the most reliable methods for accomplishing this. Consequently, demand for these systems has continued to increase, especially as consumer awareness and expectations have also increased in the wake of these actions.

Cleaning Abilities
Most production facilities use bucket elevators to handle all types of bulk materials. Unfortunately, the machine’s interior and exterior require extensive cleaning, resulting in downtime during which the conveyor can’t operate.

Tubular cable conveyors for food-grade applications are designed to be more efficient while meeting the FDA’s modern sanitation specifications. For instance, solid discs are attached directly to the cable without screws or bolts, and stainless steel connectors are used throughout the conveyor. The system also eliminates right-angle creases that cleaning agents may miss during full wash-downs.

Similar to their cable counterparts, chain conveyors are designed to meet FDA requirements. At their core is a polished stainless steel conveyor link chain or roller chain that is rated acid- and corrosion-resistant. The entire chain is directly immersed within the food being conveyed. So, cleaning the chain—and the tubing itself—does require more care than what’s needed for a cable conveyor. This is particularly true with the roller chain, where food particles can find crevices or water can remain trapped resulting in potential contamination.

Regardless of cable versus chain, each facility develops its own cleaning protocols based on its individual equipment and products. Different methods are available to clean and sanitize a tubular drag conveyor depending on the material being moved.

Line Changeovers
Line changeover sanitation and speed has become a focal issue in food production. Companies are increasingly running different product lines within a single shift or day. They are nevertheless expected to maintain clean and allergen-free operations.

This isn’t always easy. Processing plants know that every minute spent disassembling a conveyor system for cleaning consumes valuable production time. Yet, if not cleaned properly, product may end up discarded because of contamination, which means lost profit. This could also endanger consumers, resulting in potential injury, costly recalls, and damaged reputation.

“Cross-contamination and the ability to clean are the most important aspects of line changeovers,” says Bob Owen, service engineering manager of Cablevey Conveyors. Although speed in line changeovers is important, thorough cleaning is crucial when dealing with materials containing allergens. Owen also recommends the following considerations when dealing with line changeovers:

  • Does the system have the correct discharges?
  • Are you able to clean your system in between changeovers?
  • Are you wet or dry cleaning?
  • What are you using to clean it?
  • Does your material contain allergens?

Material Breakage
Material faces multiple opportunities for degradation as it moves through a conveyor. Poor inlet design, product shearing, conveyor speed, temperature changes, friction-induced separation, and so on can all come into play. Other areas of concern include discharge and liberated product impact. These represent direct threats to the material quality and cause material loss through breakage and waste.

A slow conveying tubular drag system offsets these risks. While it may seem counterintuitive for an industry that prizes speed for maximum production, faster doesn’t always mean better when it comes to conveyors. Special care is needed for conveyor systems moving specialty foods like roasted nuts, malted barley, or delicate cookies and crackers. Just like the right sizing, the right speed in a controlled environment designed specifically for this purpose minimizes the chances for product degradation (and associated degradation costs).

Guidelines for Choosing a Conveyor
Tubular cable and chain conveyors reduce the incidence of health hazards and potential for dust explosions. That’s why they’re great options for conveying bulk materials in an industry like food processing. Various factors go into assessing which tubular drag system would be best suited for your application. At minimum, these should include the following:

1) Can the conveyor be configured to operate within the facility’s physical layout? Make sure the system can maneuver the plant’s turns, inclines, declines, flights, and lifts.

2) Does the conveyor system permit flexible configuration? Some can be designed to be highly modular with easy reconfiguration, but what about others that are designed to be relatively fixed? How easy or difficult would it be to modify their configuration, and at what cost?

3) Is the conveyor designed for easy cleaning and line changeovers? Maximizing production time should never come at the expense of thorough cleaning. An oversight here can cause product contamination that’s far costlier in the long run than any time saved from negligent sanitation. Systems that permit quick changeovers while maintaining 100 percent cleanliness ultimately offer a better return on investment.

4) What are the standard preventative maintenance requirements for the conveyor system? Frequency and ease of access ought to be considered. A system that requires continual maintenance and parts replacement will affect production throughput and cost of operation.

5) How easy and timely are repairs? System failures need to be anticipated even for the most reliable automation. Getting equipment back up and running quickly is critically important for throughput. So, assess failure probability along with turnaround time for everything from technician support to replacement-part delivery to full repair and production restoration.

6) What are the operational energy requirements for reducing your company’s carbon footprint? Compare different types of conveyors (even tubular cable versus tubular chain) for the amount of horsepower required to move the desired product capacity. A 25 percent reduction here can significantly reduce your energy bills.

Morgan Bailey is communication specialist, Cablevey Conveyors, Oskaloosa, IA. Cablevey is a worldwide tube conveyor manufacturer that engineers, installs, and services tubular drag and cable conveyor systems in over 65 countries. For more information, call 641-673-8451 or visit www.cablevey.com.

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