Air Knives

CFW Fans manufactures blowers as well as knives and related accessories.

 

air knife assembly

About Air Knives

Industrial Air Knives provide an efficient, cost effective and compact solution to many cleaning, liquid film management and drying applications. A high energy stream of air does the work, hence there is no mechanical contact with the process.

The blower delivers air to one or more plenum chambers through ducts. The air exits through a slot in the plenum which is designed to direct the air into a high-speed jet. Anything in the path of the air gets blasted, so that it is cleaned, dried or otherwise altered. Usually a belt conveyor is used to transport products that are processed in this way, and air knives are also used to clean the conveying mechanisms themselves.

For fast and effective drying or cleaning, heated air can be used when a product contains absorbed moisture or has a complex shape. Some heat is naturally produced by high-pressure air movers. Products that cannot be adequately dried with an air knife may require a drying oven.

Benefits

Air knives are highly efficient for removing contaminants from surfaces and, depending on the product to be dried, often use less power than dryers that apply heating. The lack of mechanical contact with the product makes them easier and less costly to maintain than scrapers, and their high rate of operation and rapid start-up can make production faster and more consistent.

Why Use Blowers?

Air knives may be powered either by compressors or by blowers. The application and factory environment need to be carefully considered to select an air knife and the choice of air mover. Factors to be considered include:

  • The properties of any moisture or solids to be cleaned off from the product
  • The product's shape and surface texture
  • Production throughput and the conveying system

Compressor-driven units use air that is initially produced at a higher pressure and delivered to an air receiver. This air pressure is again reduced at delivery to the air knife system. As a result, the energy required to develop the differential pressure is lost.

On the contrary, blower-powered systems generate air at the required pressure. This means that power consumption is lower for blower-driven air knives, given a similar application.

The maintenance costs of compressors, as well as their size and high noise levels, mean that there are often hidden penalties to adopting this solution. Blowers can often be located closer to the plenum, since they are relatively compact. This makes for lower pressure drops and thus greater efficiency. The need to use separators or refrigerant dehumidifiers with compressed air, and fluctuating performance due to multiple demands made on the compressor in a factory, can also shift the balance in favour of blowers. The air supplied by lateral channel blowers is oil free, pulse free and requires no additional filtering other than the filter at the blower inlet.

 

The following CFW blower types are commonly used for air knife systems:

  • Lateral Channel Blower
  • BC-HT & RB-HT Blowers

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