Compressed Air Knives Perform Better than Blower Air Knives for this Bottle Drying Application

Sometimes you need more power.  I spoke with a customer from a beer bottling facility that was using blower operated air knives, not compressed air air knives.  They were needing to increase the amount of force to dry the bottles.  Their production rate was 580 bottles/min, and they were seeing issues in the labeling process due to residual moisture being left on the bottles.  Their operation consisted of a wash cycle, rinse cycle, drying cycle, then labeling.  They determined that the bottles were not getting dry enough before the labels were applied.  They used a blower system, and they were having difficulty when they reached the maximum bottle rate.  This meant that they would have to increase the size of their blower system; and, with the capital cost of blower systems, they decided to call EXAIR to see if we could help them with their drying application at a lower purchase price.  

Compressed air is the best way for establishing a strong blowing force.  Instead of air pressures in the range of inches of water, the compressed air system can generate over 40 times the amount of force than a typical blower system.  EXAIR products use the power of the compressed air system to give a wide range of blowing forces for drying, cooling, or moving products.  With our Super Air Knives, we have a 40:1 amplification ratio which means for every 1 part of compressed air, we bring in 40 parts of ambient air.  This adds mass to the airstream to make our Super Air Knives very efficient and effective. 

For the customer above, their system filled two different sizes of beer bottles.  The first bottle had a capacity of 16.9oz (500ml) with a height of 10 ½” (267mm); and the second bottle had a capacity of 28.7oz. (850ml) with a height of 12” (305mm).  For optimum blowing, we wanted to set the air knife at an angle to force the water to the bottom of the bottle.  We also want to have good contact time and blow in a counter-flow direction.  This will keep the bottles that have been dried, dry.  For Food and Beverage applications, EXAIR offers two types of stainless steel, 303SS and 316SS.  Since this was a non-contact drying application, 303SS was appropriate.  So, I recommended two units of a model 110218SS Super Air Knife kit to place one knife on each side of the bottles.  This would cover the entire bottle height with an appropriate blowing angle. 

110218SS Super Air Knife Kit

The kit includes the Super Air Knife, a filter, a regulator, and a shim set.  They mounted one knife on each side of the bottles to blow off and remove the liquid after the rinse cycle.  Even at the increased bottle speeds, the EXAIR Super Air Knives had no issues in keeping the bottles dry.  With the regulator and shim set, it was easy for them to dial in the correct amount of force without using too much compressed air.  The labels remained glued and the bottling process ran smoothly.  Because this company was impressed by the Super Air Knives, they wanted to comment on the comparisons between the blower knife and the Super Air Knife.

Comparison EXAIR Super Air Knife vs Blower type
  1. Cost:
    1. Blower System – The reason for contacting EXAIR.  Blower-type air knives are an expensive system.  They need a blower, ducting, and knives.  To have any variability in force, a control panel with a VFD will be needed.
    1. Super Air Knife – It is a fraction of the cost.  With their system, we were roughly 1/10 the cost; even with the kit.  No capital expense report would be needed for the two air knives.    
  2. Installation:
    1. Blower System – They stated that it took them a week to install the entire system before they were able to use.  They had to run electrical wires, controls, ducting, and they even had to change the conveying system slightly to accommodate the blower size. 
    1. Super Air Knife – They mounted the filter and the regulator on the conveyor, and ran compressed air line to the Super Air Knives.  Even with a fabricator to make a bracket for the Super Air Knife, they had the system up and running is less than two hours.    
  3. Size:
    1. Blower System – The foot print of the blower is large and it takes up floor space.  The 3” (76mm) ducting had to be ran to oversized air knives.  With the congestion of the bottle system, it made it difficult to optimize the position and the blowing angle to adequately dry the bottles.      
    1. Super Air Knife – With the compact design, the Super Air Knife packs a large force in a small package.  It has a footprint of 1 ¾” (44mm) X 1 ½” (38mm) X 18” (457mm) long.  The air knife only required a ¾” compressed air line to supply the compressed air.  It opened up the floor space as well as the bottling area. 
  4. Maintenance:
    1. Blower System – The blower filter had to be changed regularly, and the system had to be checked periodically.  Being that the blower motor is a mechanical device, the bearings will wear and the motor will fail over time.  These items should be checked quarterly as a PM which increases the cost to run the system.    
    1. Super Air Knife – No moving parts to wear out.  The only maintenance would be to change the filter within the Filter Separator once a year. 
  5. Quiet:
    1. Blower System – With the blower and turbulent air flow, the units are very loud.  It had a sound level near 93 dBA, and with the operators working around the system, they needed PPE for hearing. 
    1. Super Air Knife – These units are very quiet.  At 80 PSIG, the sound level is only at 71 dBA for the Super Air Knife.  This was very nice for the operators to work around as it wasn’t a constant noise nuisance. 

In using compressed air, the EXAIR Super Air Knives are engineered to be very efficient and effective.  But, even with the use of compressed air, the customer still wanted to share the ease of installation, the effectiveness of blowing, and the improvements to their process.  With the five points noted above, the customer wished that they would have contacted EXAIR at the beginning.  Now, they were able to dry the bottles to allow for a strong adhesion of the labels.  If you wish to speak to an Application Engineer about your cleaning, drying, blowing or cooling applications, we will be happy to hear from you. 

John Ball
Application Engineer
Twitter: @EXAIR_jb

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