[Equipment Spotlight] Contamination Control

From multi-million dollar brand-name companies to “mom and pop” bakeries, every sector of the food industry faces a common enemy…contamination. While Salmonella and E.coli are well-known threats, so are allergens like peanut dust that, if mixed with the wrong batch, can cost a company millions in product recalls, lost customers, lawsuits, and fines. And if FDA regulations or strict quality standards to protect consumers weren’t enough, many food manufacturers now have the Occupational Health and Safety Administration (OSHA) on their doorsteps to see if they’re one of the estimated 30,000 facilities at risk for a combustible dust explosion, making contamination control much more than housekeeping, but a matter of life and death.

There are many methods to combat food contamination. While traditional methods like mops, brooms, and compressed air seem like a quick fix, they use valuable staff-time, are limited in what they can clean, and often just move dirt and debris from one place to another.

Shop-style vacuums are perhaps the most popular cleaning equipment found in today’s industrial market. A visit to any food plant will find dozens of vacuums scattered throughout the facility. Although they may be good for ordinary light-duty housekeeping functions, most plant managers would agree that these vacuums can be expensive to operate, noisy, inefficient, and usually very short-lived. Most companies replace several of these vacuums every year, making them less cost-effective than it would seem.

While all of these methods still have a place in today’s industry, food manufacturers looking to bulk up their maintenance plans need to maximize efficiencies and control issues where they can by choosing better quality equipment. Investing in a high-quality, multi-stage industrial vacuum cleaner is a step in the right direction.

Equipped with features and benefits that outweigh mops, brooms, compressed air, and shop-style vacuums, an industrial vacuum cleaner can collect and retain particles inside the machine with little chance of being exhausted back into the atmosphere. They also can be equipped with accessories to clean hard-to-reach areas, including ceiling panels, lighting units, HEPA filtration units, sprinkler heads, walls, glass surfaces, process equipment, and piping systems. But from basic models with a collection container and a motor to vacuums with more options than a Cadillac, purchasing an industrial vacuum cleaner can raise a lot of questions.

VACUUMS 101. The first step in purchasing a high-quality industrial vacuum is understanding the basic specifications. Unlike many motored machines, a vacuum’s power isn’t always measured in horsepower, although many manufacturers of light industrial vacuums (shop-style vacuums) will use HP to make their products appear superior. Although horsepower definitely plays a factor in heavy industrial systems, there are two other components that describe the performance of a vacuum: airflow and water lift.

Airflow
Airflow is the component responsible for moving particles or debris through the hose into the vacuum cleaner. Measured in cubic feet per minute (cfm), there are several factors that affect airflow: diameter of the hose or inlet (the larger the inlet, the higher the airflow), size of the motor fans, and number of motor fans in parallel. A vacuum with high airflow is typically better suited for picking up light/fine powders like flour and dry whey.

Waterlift
Waterlift, also known as static pressure or vacuum, is the ability of a vacuum cleaner to lift a standing column of water a given distance by evacuating the air in the column above the water. As the component important for lifting heavy pieces of debris against gravity, waterlift is measured in inches of water or mercury, and is controlled by orifice size and number of motor fans in series. As an example of fans in series, a motor with a three-stage fan would have more waterlift than one with a two-stage fan. High waterlift is needed in collecting water, cooking oil or other heavier particles.

Fortunately, most vacuum manufacturers don’t expect plant managers to know the details of vacuum performance, so pre-purchase application assessments and demos are a great way to figure out whether airflow or waterlift is needed and if tailored adjustments are necessary.

In addition to the basics of vacuum performance, industrial vacuums come in many different forms for the specific needs of the food industry. From portable, intermittent-duty vacuums for general cleaning to stationary continuous-duty vacuums for process-integrated applications to central vacuums, today’s systems can be quite sophisticated.

Intermittent vs. Continuous Duty
Knowing whether you need an intermittent or continuous duty vacuum is an important step and will greatly narrow your choices. Deciding between the two mostly depends on specific application and electrical requirements. If your application requires constant extraction or collection of very heavy debris, continuous duty is the best option. Continuous three-phase power is also more economical, but not every plant is equipped with it. Single phase power is more prevalent but can limit the power of the vacuum; however, if the vacuum will be used for general cleanup of work areas for about an hour or less a day, an intermittent/single-phase industrial vacuum is your best bet.

Portable vs. Central System
Because of their bigger size and increased suction power, central systems are capable of handling several applications at one time, including local exhaust ventilation and the pickup of fine powders. The machine can also be isolated outside or in a separate room to control noise and used with accessories hooked up to wall inlets. Each system has its pros and cons, but for many manufacturers the decision comes down to the application. If you need to clean very specific areas, such as multiple neighboring rooms, a central system with a drop down hose in each working area may be best; if you need the flexibility to clean the entire plant—including stairwells, corners, and overhead areas—a portable system is most efficient. Naturally, many manufacturers have both a central system and several portable industrial vacuums to meet all their maintenance challenges.

Cleanroom
Although cleanrooms are much more prevalent in the pharmaceutical and electronic industries, many food manufacturers are increasingly using cleanroom technology and modified environments to protect certain products prone to bacterial contamination. If your vacuum will be used in a controlled environment, a High Efficiency Particulate Air (HEPA) or Ultra Low Particulate Air (ULPA) filter is an obvious must, but the location of the filter is also critical. Placed downstream or after the motor, these filters will eliminate the dust created by the motor’s commutator and carbon brushes from being released back into the environment through the exhaust stream. An upstream or after-the-motor filter protects the motor from the potentially harmful debris being collected, prolonging the life of the vacuum.

Simple, smooth construction is also important for a cleanroom vacuum as it prevents contamination by the vacuum and is easier to clean. Non-particle-generating material such as non-porous stainless steel is a preferred material in controlled-environments, and hoses and attachments should also be smooth for fast, simple sanitization and validation.

Wet or Dry?
Don’t forget to take spill response into account when purchasing a vacuum. If you try to collect liquid with your dry-only vacuum you can easily ruin your investment and cause serious injuries. Wet-collection vacuums must have a grounded, by-pass motor to avoid electrical hazards. A stainless steel or polyethylene tank to prevent corrosion is also a good feature to look for, along with an automatic shut-off valve to prevent overfilling.

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The Basics of Vacuum Filtration

Filtration is often what sets apart a high-quality industrial vacuum from a shop-style vacuum. There are four primary factors that affect filtration: particle size, air speed, filter media and running time.

• Particle size – The smaller the particle, the more difficult it is to filter. As particles become airborne, they align themselves with the flow of the air stream, making it easier to penetrate filter media that is too porous. It is this factor that makes a series of graduated filters a critical vacuum component; even tiny particles that make it through the first few layers of filtration will be stopped by the finest filters, ultimately the HEPA or ULPA.

• Air speed – Velocity, or air speed, refers to the pace at which particles move through the hose and into the vacuum cleaner. The faster the particles travel, the deeper they will penetrate into the filter media. A particle traveling at a high speed may build up enough force to go through the pores of the filter material; however, a particle traveling at a slower speed will be caught on or between the fibers (or weave) of the media. A HEPA-filtered vacuum cleaner with a cyclone or paper-bag filtration stage slows the air down as it enters the machine, preventing particles from gathering too much velocity and enabling the other filters to operate at peak efficiency.

• Filter media – Filtering efficiency is affected by the relationship between the surface area of the filter media and the volume of air trying to pass through it. This relationship is known as the “air-to-cloth” (ATC) ratio; the lower the ATC ratio, the more efficient the filtration system will be. The ATC ratio is largely determined by the size of the filter; the larger the filter area, the more efficiently the vacuum can filter debris because there is a larger space in which to trap particles, and less frequent filter clogging. Therefore, the optimum ATC condition is a slow airflow through a large filter.

• Running time – As the vacuum operates, debris will build up on the surface of a filter and embed itself into the filter material, clogging the filter (also known as “blinding” or “loading”). A certain amount of loading is good for the filter; it improves efficiency by making it harder for the particles to penetrate the filter. However, when the filter becomes completely clogged, vacuum suction is reduced and performance suffers. Filters with a low ATC ratio, i.e., with a larger surface area, can operate for longer periods of time without clogging, enabling workers to maintain maximum suction and vacuum performance.

Combustible Dust National Emphasis Program. (11 Mar 2008). Occupational Health and Safety Association. http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=DIRECTIVES&p_id=3830

Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions. (31. Jul 2005). Occupational Health and Safety Association. http://www.osha.gov/dts/shib/shib073105.html

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FILTRATION, FILTRATION, FILTRATION.
No matter what type of vacuum you choose to safeguard against multiple sources of contamination, superior filtration is key, and in most cases, is what sets apart a quality vacuum from an investment that will quickly end up in the trash. For peak operating efficiency, a vacuum should have a multi-stage, graduated filtration system, which uses a series of progressively finer filters to trap and retain particles as they move through the vacuum. Levels of filtration may include cyclonic, paper bag or polyliner, main filter, micro filter, and HEPA/ULPA filters placed before, and/or after the motor. As previously mentioned, HEPA and ULPA filters have become standard in many sectors of the industry, even outside of clean rooms, and a multi-stage system is key in protecting these filters from blockage and excessive wear and tear, maintaining peak performance.

Ideally, a vacuum’s filtration system should use oversized filters, which slow airflow action across a larger surface area to optimize the air-to-cloth ratio. This allows the vacuum to easily collect large volumes of debris over extended periods of time—while  minimizing maintenance. A feature that also increases efficiency and prolongs the life of a vacuum is a main filter purging system. Whether automatic or manual, this allows the operator to regularly shake the filter to dislodge caked-on dust without having to open the vacuum cleaner. Regularly shaking the filter maximizes the vacuum cleaner’s performance and eliminates down-time.

IT’S ELECTRIC. Although workplace blasts are not new, manufacturers have certainly seen more in the last few years. The food industry is particularly at risk for such explosions, working with combustible materials like sugar, coffee dust and cornstarch. In February 2008, a Georgia sugar manufacturer experienced one of the worst workplace explosions in history. In addition to 14 fatalities and numerous injuries, OSHA recently fined the company more than $8 million for workplace safety violations. In response to the recent rise in facility blasts, the agency has made preliminary prevention recommendations that include incorporating an industrial vacuum into maintenance plans, but choosing the wrong vacuum can actually add to the risk.

A vacuum used to collect combustible materials (as outlined in NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids) should be certified explosion-proof to the core. Everything from the outer shell to the internal mechanics, including the motor, switches, filters and inner chambers, should be grounded and constructed of non-sparking materials, such as stainless steel. Some companies offer basic models dressed up with a few anti-static accessories and describe them as suitable for explosive material. These imposters may still create arcs, sparks or heat that can cause ignition of the exterior atmosphere and overheating that can ignite dust blanketing the vacuum. Approval by a nationally recognized testing agency such as the Canadian Standards Association or Underwriters Laboratory is imperative and will clearly define if a particular vacuum model is certified for use in your specific NFPA-classified environment. It also provides legal certification and ensures that every vacuum component meets strict standards for preventing shock and fire hazards.

Although it is rare for a food facility to use pneumatic machinery, there are times when electricity is unavailable or undesirable. For these environments, pneumatic, intrinsically-safe vacuums are a reliable option. Although testing agency certification does not exist for air-operated machines, an intrinsically safe vacuum should meet the same standards required for their electric counterparts.

CONCLUSION. If used properly and consistently, buyers can get a return on their vacuum investment in as little as six months, but like all investments, pre-sale research is key. Visit manufacturer Web sites and talk to sales reps. A company that is knowledgeable about your application will be better able to assess your needs and make recommendations. Naturally, every manufacturer will be responsive to your needs before you buy, so look for a company that will still be there when the dust settles. Excellent post-sale support will make it easier to purchase replacement parts and filters or service your vacuum.
Under the burden of such heavy regulations, the food industry must continuously evaluate housekeeping regimens to ensure that all areas are properly cleaned and maintained. There are many options, but as proven by too many tragedies, a solid maintenance plan is critical and investing in the correct industrial vacuum for your application is more than just a cleaning solution. Purchasing the right vacuum can save money, protect the integrity of the product, increase productivity, and most importantly, safeguard the health of your personnel and loyal customers. AIB

The author is Vice President & General Manager of Nilfisk CFM.