Extra Shims Give Super Air Knives A Boost

The EXAIR Super Air Knife is the most efficient and quietest compressed air blow off knife on the market. We know this because we’ve tested them, and our competitors’ offerings, for performance, using the same instruments, controls, and procedures. We’re not going to publish data that we can’t back up, and that’s a fact.

We will use the same precision calibrated equipment, by the way, to test your existing products for savings comparison in our Efficiency Lab service.
We will use the same precision calibrated equipment, by the way, to test your existing products for savings comparison in our Efficiency Lab service.

They’re also ideally suited to a wide variety of applications – they come in lengths from 3 inches to 9 feet long (and can actually be coupled together for uninterrupted air flows of even longer lengths,) a variety of materials for just about any environment, and changing performance is as easy as “dialing in” a regulator, or, for gross adjustments, installing a different (or additional) shim.

As the title of this blog suggests, a larger shim gap will give you higher flow and force from your Air Knife. Honestly, the 0.002″ shim that comes pre-installed in all of our Air Knives is perfectly suitable for most blow off applications, and appropriate air supply conditions are the first thing you should check for before going with thicker shims, but if you do indeed need a boost, a thicker shim will indeed give you one…here’s a video to show you how it’s done:

Keep in mind that appropriate air supply is going to be important here as well…by increasing the shim gap, you’re increasing the amount of compressed air flow required.  This means that you may need a larger diameter of infeed pipe to carry that much air, and/or you may have to plumb that air to additional ports on the Super Air Knife.

This is from the Installation & Operation Guide that ships with your Super Air Knife. It's also available from our PDF Library (registration required.)
This is from the Installation & Operation Guide that ships with your Super Air Knife. It’s also available from our PDF Library (registration required.)

For most cases, we can use the above data to determine how to properly supply a Super Air Knife with additional shims.  For example, let’s look at a 12″ Super Air Knife:

*With a 0.002″ shim, you’ll need a 3/8″ pipe, assuming infeed length of 10ft or less, to pass the 34.8 SCFM that this unit will consume when supplied @80psig.

*By installing a 0.004″ shim, you’re doubling the air consumption, which means it’ll consume the same amount as a unit twice this length…we can see from the chart, then, that a 24″ Super Air Knife will need a 1/2″ infeed pipe.

*Also, since you’re using the same amount of air as the 24″ Super Air Knife, the 12″ unit should be treated like the 24″ one, and plumbed to (2) inlets at opposite ends of the knife (see “Compressed Air Supply” notes above.)

This is just one simple case for a small unit. If you’d like to discuss altering the performance of your Super Air Knife, give us a call.

Russ Bowman
Application Engineer
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