subject: How Does Air Knife Work [print this page] Air knife is a non-conventional, low-cost and flexible device found useful in various processes and application in many industries.
This mechanical tool, which seems unassuming and simple, is functional enough to be utilized for a variety of applications including cleaning, blow off, cooling and drying. To perform these functions air knives do not require electricity, but only compressed gas which is supplied to the mechanical device.
Typically, air knives or air blades manufactured for commercial use measure 0.25 to 200 inches in length. While the holes across the tools surface have a diameter of 0.001 to 0.25 inches each. The air produced by the device ranges from gentle breeze to up to as great as 40,000 feet per minute.
Air blade used for great volume production line in a stationary operation can be produced by connecting various blades to create greater length. To create air stream, a generator is required to supply the air which can either be an industrial blower or an air compressor.
Various reasons such as environmental and efficiency are considered in choosing which type of generator will be used to power an air knife. The pipe sizes which supply air into the blade can be as small as inch in diameter which is applicable for constrained areas. On the other hand, blower-powered air knives require larger pipe sizes.
Air knives manufactured these days have teardrop shape which is very efficient with a 0.95 coefficient of discharge. The profile of blower-powered air knives with this design usually measure 3.5 inches wide, 5.5 inches height and can be of any length. Depending on the width and velocity of the product, the air knife is capable of performing a blow off at distance 0.5 to 12 inches or even farther from the surface of the product. Moreover, those with nozzles of 1 to 4 inches diameter can still be effective against surfaces several feet away.
To function, air knife draws air surrounding the device as well as the compressed air supplied to it. The device creates a laminar or curtain-like air flow across the length of the blade which is used to clean, dry or cool the product passing through the stream.
Air knives are commonly utilized to remove excess particles, either liquid or solid, from a materials surface. Among the applications include drying and cleaning printed circuit boards after being washed to remove excess adhesive and flux; and drying of bottles and cans after they are filled and rinsed.
