The Key To Controlling Airborne Contamination In Food Processing

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Courtesy of Camfil Ltd

In the food and beverage industry, contamination is always a high priority concern. Small mistakes in handling, preparation, and even in the cleaning of the environment where food comes into contact with surfaces can cause disastrous results that can potentially affect hundreds of thousands of people.

Often overlooked is the threat from another source of food contact: air.

Air is an Ingredient in Food

Outdoor air can naturally carry anywhere from 200 to 1500 bacteria per cubic meter. The natural defense mechanisms in our living bodies respond to most potential hazards from these bacteria with ease. However, that’s not always the case with food as anyone who has left meat sitting out on the kitchen counter for too long can surely confirm. Add to this the fact that an air handling system pushing tens of thousands of cubic meters of air per minute can pull 15 million bacteria per minute or more into a building, and you’ve got cause for serious concern.

Proper Filtration can Help Prevent Catastrophic Contamination

Governmental agencies regulating the food industry do not provide a comprehensive list of recommended filtration levels for all the various foods processed in today’s world. While there are some guidelines offered, the ultimate decision as to what level of filtration is required is left up to individual facilities.

Plant personnel should work with qualified professionals to determine the metrics of potentially harmful bacteria in the air outside their plant as well as what’s generated within the facility and recirculated. This identification will guide in selecting the level of filtration efficiency necessary to provide a safe processing environment. Refer to the most recent ASHRAE® Merv rating chart for an understanding of capture efficiency levels.

Equipment and Filter Configuration

While there is a wide variety of air handling equipment in service throughout the food industry, the typical equipment is a rooftop unit which contains a heating or cooling element and two stages of filtration. Often times, the heating element is at the front of the unit while the cooling element is sandwiched between the two filtration stages. These heating and cooling elements can be a source of moisture which must be controlled as well as moisture from the outside environment, rain or snow. A major source of moisture is from exhaust vents located near the air handling unit’s intake hood. If the air handling unit is not equipped with moisture separators, filter performance suffers.  

The first stage of filtration is often referred to as the prefilter. Historically, this has usually been a coarse filter with a lower Merv rating and limited service life. This filter’s main function is to remove large debris and to protect any heating or cooling coils immediately downstream. New advancements in filter technology are allowing higher Merv rated filters with extended service life to both protect the downstream equipment, assist in removing excess moisture and begin the process of readying the air for food contact.

The second stage, or the final filter, is the critical one in terms of food safety. It has two vital functions which it must perform continuously while in service. This filter must both capture the size and percentage of particles identified as harmful to the particular process while at the same time, maintaining a low-pressure drop so airflow is not compromised.

Filter Selection

There are many filters on the market today which are labeled with higher efficiency ratings such as Merv 13, 14 or even 16. However, once put into service, these filters loose capture efficiency and can drop to unacceptably low Merv ratings for a food or beverage facility. To avoid this, select filters which publish their Merv – A rating which is a test standard designed to mimic real life conditions. A simple Merv 14 filter can actually drop in efficiency as low as a Merv 11 while a Merv 14A filter will maintain that Merv 14 efficiency for its entire service life.

Similarly, in order to gain an understanding of a filter’s consistent airflow potential, request the full ASHRAE® 52.2?2007(B) Test Results w/Appendix J report and carefully compare DHC (dirt holding capacity) figures at recommended final pressure drop. This will give insight into the ability of a filter to provide adequate airflow as it begins loading with dirt.

Camfil Products Stop Contamination

Camfil provides a full range of air filtration systems designed specifically for the sensitive needs of the food and beverage industry. Camfil air filters are capable of removing microscopic particles from the air to help ensure the highest level of protection while at the same time, maintaining the lowest average pressure drop to sustain proper air flow.

The superior engineering techniques and raw materials that deliver these critical results also provide increased cost savings over competitive products by providing a significantly longer filtration service life, reduce the quantity of filters that need to be ordered and disposed of, and significantly reduce the power consumption of fans and circulation equipment.

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