Air Knives - Air Knife Design

Compressed Air Versus
Air Knives / Air Knife Systems

Effectiveness and Cost Comparison of typical compressed air blow-off systems versus Turbotech HVLP Air Knives and air knife systems.

Because of our application approach we recognize that blower powered air knife systems are not the only solution to every application. Our expertise and development is focused on blower-powered air knife solutions but we appreciate the need for a different solution in some circumstances. We sometimes recommend and sell compressed air devices. Having explained our perspective we don't want to sound biased in this next assessment.

Compressed air blow-off has the following advantages and disadvantages. Compressed air systems are inexpensive to purchase and do not add a huge operating expense if you only need one or two blow off points with intermittent operation and you have enough extra capacity in the companies 300 HP compressed air system so that other plant usage is unaffected. Tight areas require a compressed air solution.

However, if there are more than four blow-off stations and they are used more than a couple hours a day the operating expense begins to grow tremendously. Often this results in other plant systems being starved for air. Additionally, if there are employees spending time blowing material or moisture off product rather than working productively, this also adds to the cost. A typical compressed air blow-off situation has the plant engineer and maintenance man solving a problem by drilling holes in a pipe, and connecting it to the plant air system. They often don't realize their 300 HP compressor now kicks on five additional times each day. The real expense occurs when the plant does this three or four more times because it did the trick the first time. Now, the compressor is running constantly.

The above “application” of compressed air for blow-off represents an un-planned development of plant operations and increased expense. This can represent a huge cost for a plant utility that has just been tripled or worse.

Increased cost aside, there are other things to consider; plant air is wet, and often oiled, so it must be filtered at the point of use because it makes no sense to attempt to dry or clean a part with cold, wet, oiled air. If it is a liquid being blown-off compressed air tends to atomize the liquid into a mist that can actually contaminate a wide area; adding to problems you are trying to solve. There are companies selling compressed air nozzles that indicate that their nozzles multiply the volume of air by five times (some more some less) by pulling surrounding air with the compressed air (Bernoulli principle).

The principle is true, but in actual application it may not effectively add any air to the product. If their claim is true to any degree then high speed air from any air device will do the same. So it is not a unique benefit of compressed air systems. We have often replaced compressed air system with a blower-powered air knives and the customer has gained the following benefits:

1. Most importantly their blow-off is more effective because of volume of clean, dry air, applied to the part. (Usually an air knife system creates 5 to 10 times the volume of compressed air.)
2. They returned their compressed air back to the work it was intended for and did not have to invest in a new additional compressor to operate production machinery.
3. The operational cost of air knives can be 25% of the comparable compressor air cost and often pays for the initial investment within the first year; adding savings from then on.

In summary, replacing your compressed air blow-off operations for cleaning, drying, and cooling with air knives will result in lower utility costs, enhanced compressor capacity, truly clean parts, and improved plant air quality. Make the switch today. Contact a applications engineer at info@air-knives.com.