Compressed Air

Compressed air systems are used in a variety of processes within the food production environment. These systems supply compressed air for processing and packaging equipment functions, as well as for cleaning of the facility and equipment. Since compressed air systems can be used in a variety of food plant applications, the system design needs to consider possible food safety aspects of how the compressed air will be used. A compressed air system is comprised of three basic components: air compressors, air dryers, and air filters.

Air Compressors

Compressed air that contacts food in any way must be free of contaminants. Contaminants include water vapor, moisture, solid particulates (including spores), oil aerosols and vapors. Two basic types of air compressors are used in a food facility:

Oil-injected compressors 

Oil-injected compressors are less expensive and require less maintenance. They also tend to tolerate warmer and cooler operating environments better. Food-grade lubricants must be used with these compressors.

Oil-free compressors

Oil-free compressors reduce the risk of oil entering a food product. These units require careful maintenance and a temperature-controlled environment. They are also more costly compared with oil-injected units.

Air Dryers

Compressed air contains trapped water vapor as part of the compression process. This vapor will condense in the air lines after exiting the compressor. To reduce the moisture in the air lines, an air dryer is required. Two basic types of air dryers are utilized:

Refrigerated air dryer

A refrigerated air dryer will reduce the compressed air dew point to approximately 36 °F by cooling the air and condensing the water vapor. It is not possible to achieve dew points below freezing with a refrigerated air dryer.

Desiccant air dryers

Desiccant air dryers remove the vapor by flowing the compressed air through a desiccant material bed which absorbs the water vapor. These systems contain two “towers” containing the desiccant bed. The bed in the first tower will eventually reach its maximum absorption capacity. When that occurs, the air is switch to the second tower located alongside the first. The first bed is then regenerated to remove the absorbed water by heating the bed. Desiccant dryers can deliver air at consistently low dew points: typically, -40 °F or less. This technology is a good choice when the compressed air is subject to freezing conditions.
Our engineers are familiar with the air dryers available, as well as the energy and costs associated with each option.

Air Filters

A filter should be installed at the point of use for each compressed air line. This filter will remove any remaining water that may have accumulated in the line, as well as any oil or other contaminates. Our team understands the various filtration products and associated maximum micron ratings that may be necessary for the removal of solid particles, oil (coalescing filters) and oil vapors (activated carbon filters).

When compressed air enters a food prep, production, packaging, or storage area—but does not meet food directly—it is considered non-contact, yet high-risk. This situation occurs with processes such as blow molding, where air is used to create packaging prior to filling (or in blow-off applications in bakeries to remove dust from equipment). Compressed air is also used in sanitation system for the creation of foam at cleanup stations.

All website contents and information © Food Plant Engineering, LLC. All rights reserved.