Thinner Shim Reduces Super Air Knife Compressed Air Usage

It is a typical call to receive from customers looking to replace an inefficient,  commercial grade or homemade compressed air product. Nearly always, customers can save dollars by using their compressed air more efficiently through an engineered product like ours. The performance characteristics of EXAIR products are presented at a pressure and air consumption capable of solving most industrial applications, but these performance numbers can be increased or decreased in a couple of ways. One way is by adjusting the inlet air pressure. The force, flow and volume will increase or decrease with increased or decreased pressure. Secondly, some products like Super Air Wipes, Super Air Knives and Super Air Amplifiers have an internal shim which can be changed to increase or decrease the precision air gap of the product. Applications like the following benefit from changing the shim in these products:

I worked with a customer who was using our 9″ aluminum Super Air Knife to dry a ceramic block with several individual cells. The unit was working great and they were looking to add another machine to their production line but since the Super Air Knife came with the wash coating machine, they were unsure how much air they were using and were concerned the demand on their compressor might be too great. As mentioned above, one way to reduce the air consumption would be to use a pressure regulator to adjust the supply pressure as well as control the output flow and velocity. Another simple way to control the airflow would be to change the shim to a different thickness. (for reference, here’s a video blog showing how to change the shim on a Super Air Knife)


The Super Air Knife is shipped from stock with a .002″ shim installed which is red in color. I asked if they knew what shim was in the knife and they didn’t have the thickness but knew it was green not red. That was all the info we needed, the green shim is .003″ thick and certainly overkill for removing a water based liquid from most surfaces. The performance spec chart below references the air consumption per inch with the .002″ shim installed. With the .003″ shim installed, these values would increase by 1.5 times.

Super Air Knife Performance
Chart showing air consumption (per inch) at various supply pressures.

I recommended the customer order the .002″ shim, which the OEM had removed and replaced with a larger shim. This would cut the current air consumption rate from 39 SCFM at 80 PSIG to 26 SCFM at 80 PSIG. That was what it took to get the application solved and to increase production with a new machine.

Justin Nicholl
Application Engineer



4 thoughts on “Thinner Shim Reduces Super Air Knife Compressed Air Usage

  1. I need a super sharp air stream to be flown over a box. The air stream should not get thicker as it travels. Could you please suggest me which model of 3 inch air knife will do this job ?

    1. Mahavir,

      The airstream out of the Super Air Knife is quite thin and powerful – however, it is not possible to keep the air from expanding once it has exited the air knife. The air will get thicker. Here is a link to a website page showing the airflow pattern, perhaps you can still work with it.

      Thank you,
      EXAIR Corporation

      1. Dear Kirk Edwards,

        Thanks for your reply. Could you please suggest best 3 inch model to serve my purpose of shielding a box (cube) of 60 mm size from ambient environment including operating pressure, shim size etc. Please tell me if you have semi rigid type of mounting for the air knives so that their final position can be adjusted.

        Mahavir Singh

      2. Mahavir,

        Our International Technical support team will respond to you today with details of your request. Thank you for your interest.

        Kirk Edwards
        EXAIR Corp.

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