How Air Knife Systems Work

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Air Knife System

Air Knives are simple and highly efficient devices for drying and cleaning products. An Air Knife System uses a high intensity, uniform sheet of air which is used to effectively:

  • Remove liquids
  • Control the thickness of liquids
  • Dry liquid coatings
  • Remove foreign particles
  • Cool product surfaces
  • Create a hold down force to assist in the mechanical bonding of materials to the surface

Air Knives are often the most efficient and effective method of removing or controlling foreign substances for any surface. Most Air Knives are stationary with products passing through them on a conveyor however there are also systems where the product is stationery and the Air Knives move around it. The potential that Air Knives provide for many different kinds of industries is therefore enormous.

Step by Step guide through an Air Knife System

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Overview of a typical Air Knife System

 

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1

Air compressed by high speed Centrifugal Blower.

 

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2

Pressurised air delivered to the Air Knives through the connecting pipework.

 

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3

Air is discharged through the Air Knives as a high impact linear flow of air. This air collides with the product and shears the liquid from the surface.

 

Air Knives Technical Information

An industrial air knife is a pressurized air plenum with a continuous slot through which pressurised air exits in a laminar (uniform) flow pattern. The exit air velocity creates an impact air velocity onto the surface of whatever product the air is directed to. This impact air velocity can range from a gentle breeze to greater than Mach 0.6 = 454 mph = 731 kph = 40,000 fpm = 203 m/sec. Therefore an air knife alters the surface of a product without mechanical contact.

Air knives on a production line usually range from 100 to 3048 mm (4 to 120 inches) in length with a discharge air slot ranging from 0.40 to 2.0mm (0.015 to 0.08 inches). A stationary air knife configuration can require from one to ten or more air knives depending on the application criteria. Air is blasted through the air knife slots via a high speed centrifugal blower to deliver the predetermined exit air volume and velocity needed. Electrical currents from anti-static bars can also be injected into the exit air knife stream to neutralize the static electricity charge on some surfaces.

Video: Air Knife Drying Close Up