Cleaning A Super Air Knife? Know Your Materials.

IMG_5227
An Aluminum Super Air Knife, disassembled and showing how a clean unit should look

While having dinner with some friends a few days ago, another engineer in the room asked what I did for a living and where I work.  When I told them I work for EXAIR, they immediately knew the name and commented on our Super Air Knives.  This gentleman was an automation engineer and has used our Super Air Knives for automated blow off.

The ability to automate and control an instantaneous blow off makes the Super Air Knife a versatile tool in an automation application.  But, how do they stand up to cleaning over time?

The answer, is that when properly configured for the application a Super Air Knife can last indefinitely.  If the temperatures are below 82C (180F) and there is no caustic chemical used for wash-down, an aluminum knife can usually fit the bill.  But, when a caustic chemical is to be used for wash-down, a stainless steel knife, or specially configured aluminum knife must be used.

This advice was not heeded by one of our overseas customers, and the results of what happens over time are shown below.

SAK with deteriorated shim 3
Polyester shim of an aluminum Super Air Knife after the unit was cleaned with Sea Foam
SAK with deteriorated shim 4
Cap of an aluminum Super Air Knife after the unit was cleaned with Sea Foam
SAK with deteriorated shim 2
Body and cap of an aluminum Super Air Knife showing the results of improper cleaning

This customer coated the exterior of an aluminum Super Air Knife with a product by the name of Sea Foam.  The surfaces and air slot of the knife were completely covered with Sea Foam, and then the exterior was wiped down.  Over time, the Sea Foam entered into the plenum chamber of the knife and caused the polyester shim to deteriorate.

Sea Foam is a wonderful product that has found a home in many shops and maintenance departments, and for many applications it presents an excellent cleaning agent.  But, for an Aluminum Super Air Knife, it poses a problem.  But why?

Sea Foam is a combination of Isopropyl Alcohol (10%-20%), Naphtha (25%-35%), and Pale Oil (40%-60%).  Isopropyl alcohol is a solvent, naphtha is petroleum distillate that is highly flammable, and Pale Oil is a heavy distillate naphthenic oil refined from wax-free crude oil.  These characteristics make the product a “go-to” cleaner for carbon/dirt buildup, especially on metal surfaces.  But, these same characteristics are “bad news” for polyester (Aluminum Super Air Knifes use polyester shims), and over time will cause the polyester to break down (as shown in the photos above).

So, what is the solution?  First and foremost, the solution is to follow the cleaning instructions found in our Installation and Maintenance (I&M) guide.  We provide an I&M guide with every product we sell, and have free downloads available on our site here.  But, to remedy the current condition in this application we recommended one of two actions.  The first is to use a Stainless Steel Super Air Knife which will be able to handle Sea Foam.  And, the second is to make a stainless steel shim for this aluminum knife made of 0.002″ stainless steel shim stock.  Either of these solutions will not only correct the present condition, but will prevent such a problem from occurring in the future.

For our end user in this case, a short, thorough discussion with an EXAIR Application Engineer could have saved them downtime and headache.  If you have an application involving EXAIR products, never hesitate to give us a call.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

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