1. MillerCoors – Albany December 4, 2008
Identify drying challenges
Demonstrate correct installation and maintenance of all components

2. Drying Challenges
Drying the top and sides of containers using a standard 3 air knife system does not remove all moisture under the crown.
Installing air knives outside of conveyor guide rails without cutting the rails creates turbulent air flow upon contact with rails and increases the distance from the air slot to the product. This distance can be insufficient for drying.
Improper orientation of the air knives will lead to improper drying.

3. Drying Challenges
Inconsistent air slot gaps will create inconsistent flows and pressures along the air slot length.
Failure to adhere to recommended plumbing diameters, distances and bend radii increases friction loss which decreases pressure/exit velocity at the air knife.
Improper or inconsistent maintenance of all system components will lead to poor quality.

4. Proper installation of air knife drying system components.
Conveyer guide rails must be cut to provide room to mount air knife air stream within ½” of the container surface to be dried. The following pictures indicate improper air knife installation at various points in production lines.

7. Angle and distance from product is inefficient and increases blower size in order to remove water.

8. Blowing through guide rails creates turbulent air and decreases system drying ability.

9. The air knife must be installed with the leading end at the top of the container and the trailing end at the bottom of the container perpendicular to the container +/- 3º of rotation on one side air knife to attenuate noise.
Proper orientation of air knives provides the most efficient drying available. The following pictures illustrate improper orientation as noted at various installations in production runs.

10. Contamination being introduced to dry product.

12. Inefficient use of air stream

13. Orientation incorrect. Air stream can not shear water at this angle.
Correct angle
Orientation incorrect. Air stream can not shear water at this angle.

15. A properly designed air knife drying system encompasses many factors such as the dimensions of the product being dried, the speed the product is moving, the material to be removed i.e. water, soap, solvents etc. One of the most important design characteristics is the gap of the air knife slot. As the gap is increased, the flow increases and pressure decrease. After installation, an air knife drying system must not have the vital characteristics changed such as the air gap, total length of air knives, motor size etc. In doing so, you will diminish the ability of the system to perform as designed. The following pictures show several examples of improperly installed and/or maintained components.

16. Adjustment screw missing allowing gap to increase, pressure decrease and creates unstable laminar flow along entire air slot.

17. Insufficient bend radius

18. Air knife can not dry at this distance and orientation

19. Reducing diameter after a 90º creates pressure loss.
Insufficient bend radius increases friction loss.

20. Corrosion on aluminum knives can lead to the degradation of the original gap size. This of course will lead to improper drying. Stainless steel should be used in extremely wet areas. The blower intake must be positioned so as not to allow water, soap or lubricants to be drawn into the system and forced through the air slot causing internal corrosion as well as depositing contaminants on the product to be dried. The following picture illustrates a breach in the intake assembly that should be repaired.