FAQ

Aluminum Air Knife with plastic shim: 180°F (82°C)

Aluminum Air Knife with stainless steel shim: 400°F (205°C)

Stainless Steel Air Knife with plastic shim: 180°F (82°C)

Stainless Steel Air Knife with stainless steel shim: 800°F (427°C)*

*Temperatures that exceed 800°F (427°C) may produce intergranular corrosion that can eventually plug the air gap opening.

No, blowers are not a source of air for Air Knives. Air Knives are designed to use compressed air. Blowers are large, expensive and noisy with 3" to 6" outlet connections. They do not produce enough pressure to operate an EXAIR Air Knife.

The maximum pressure of the Air Knife (Super or Standard) is 250 PSIG. We recommend using the lowest pressure possible for the application. Always use a pressure regulator on the compressed air supply and increase pressure to the point where the application problem is solved.

The flow characteristics of the Air Knife (Super or Standard) have been tested before it was shipped. We suggest that you follow the disassembly instructions and inspect the Air Knife for dirt contamination.  Cleaning instructions can be found on the installation and maintenance sheet shipped with the Air Knife or in Adobe Reader PDF format on our web site. A second possibility is that the Air Knife has been undersupplied. Do not use restrictive fittings, undersized line or filters that may not allow enough airflow into the plenum chamber of the Air Knife.  Air Knives that are 18" or longer must be supplied at two compressed air inlets at opposite ends of the Air Knife. A third possibility is that the screws may have been over tightened during mounting or during reassembly. Screws should be tightened snugly (7.5 ft/lbs).

Yes, EXAIR Stay Set Hoses can be used with smaller sizes of our Air Knives. Please contact an Application Engineer to discuss your specific requirements.

No, field modification is not possible due to the internal machining of an Air Knife. Cutting the Air Knife would expose the internal plenum with no practical means of resealing it. Air Knives may be ordered in any custom length.

No, an Air Knife is not position sensitive. The airflow is effective in any direction.

We offer one-piece lengths from 3" to 108" for our Super Ion Air Knife and 3" to 48" lengths for our Standard Ion Air Knife. Custom lengths are also available - contact an Application Engineer for assistance.

EXAIR’s Super Air Knives are stocked on our shelf in:

• 6061 aluminum
• 303 stainless steel
• 316 stainless steel
• PVDF (Polyvinylidene Fluoride)

We also manufacture non-stock Super Air Knives from PVC upon request.

Standard and Full Flow Air Knives are stocked on the shelf in:

• 6061 aluminum
• 303 stainless steel

You have three mounting options:

1. EXAIR manufactures the Universal Air Knife Mounting System which can be used for all styles of Air Knives and Ion Air Knives.
2. Use existing mounting holes/capscrews.
   1. The Super Air Knife has 1/4-20 tapped holes on 2" centers along the length of the Air Knife which can be used for mounting.
   2. With the Super or the Standard Air Knife you may choose to replace the existing capscrews with longer 1/4-20 threaded fasteners for mounting.
   3. The Full-Flow Air Knife has 10-24 tapped holes on 1-1/2" centers along the length of the knife which can be used for mounting, or you can replace the existing 10-24 capscrews with longer threaded fasteners.
3. For Super and Standard Air Knives, you can hard plumb the air lines to both ends and use the piping to support the Air Knives. Plumbing to both ends is required for Air Knives 24" and longer, but is also perfectly acceptable for shorter lengths.

The Plumbing Kit is an accessory item we offer for Air Knives that are 24" (610mm) in length or longer.  Any Air Knife that is 24" (610mm) or longer should be plumbed with compressed air fed into two or three inlets, depending on the length. The Plumbing Kit will connect the necessary air inlets of the knife with the properly sized hose and fittings. It also results in only one individual connection you will have to supply your air into, simplifying the installation of the knife. You can choose to install the plumbing kit or have EXAIR install it at the factory. The Plumbing Kit is to help ease the installation of the longer Air Knives.

The polyester shims are as listed below:

• 0.001" (0.03mm) - Amber
• 0.002" (0.05mm) - Red (Stock)
• 0.003" (0.08mm) - Green
• 0.004" (0.10mm) - Tan

To achieve a higher force of air flow from the Super Air Knife, Standard Air Knife, or Full-Flow Air Knife you need to increase the volume of air being put through it.  This can easily be done by increasing the supply pressure and/or using a shim set. By increasing the shim thickness within the knife, the air volume and force generated on a target will increase. Please keep in mind this will directly affect the volume of air that is required to properly supply the knife; so proper plumbing techniques should be applied when connecting the Air Knife to the compressed air source.

400°F (204°C)

No, for proper operation, the Vortex Tube cold outlet should not be subjected to any restrictions that would produce backpressure in excess of 5 PSIG. An Air Knife would restrict the flow of a Vortex Tube to the point where the backpressure is excessive and severely limit the cooling capacity of the Vortex Tube. The design of the air knife is to entrain large amounts of ambient air and add it to the airstream reaching your parts. The dilution of 1 part of cold air mixed with 30-40 parts of ambient temperature air will result in air temperatures reaching your part to be not much different than ambient temperature.

No, for proper operation, the Vortex Tube cold outlet should not be subjected to any restrictions that would produce backpressure in excess of 5 PSIG. The hot end exhaust can withstand pressure up to 30 PSIG (depending on the cold fraction). If backpressure exceeds 5 PSIG, then the performance of the Vortex Tube will deteriorate. The hot end exhaust can withstand pressure up  to 30 PSIG (depending on the cold fraction).

An Air Amplifier or Air Knife would restrict the flow of a Vortex Tube to the point where the backpressure is excessive and severely limit the cooling capacity of the Vortex Tube.

If the goal were chilled airflow coming from an Air Amplifier or Air Knife, it would be unrealistic to expect a temperature decrease in the total output flow of either device with chilled compressed air. Compressed air will make up a small fraction of the total airflow output from these devices. The net temperature out will be a mix of compressed and ambient air with ambient air the majority of the volume. The net effect is that the airflow is going to be the same or very close to ambient temperature surrounding an Air Amplifier or Air Knife.

It is important to know that the Air Knife is working properly before increasing the gap opening of the Air Knife (installing thicker shims). Low flow could be the result of restrictive fittings, undersized lines, a clogged filter, an undersized compressor or dirt clogging the slot of the Air Knife (Super or Standard). Using a pipe tee, install a pressure gauge at one of the inlets of the Air Knife to insure that full line pressure is available to it. If full line pressure is available and additional flow is required, shut off the compressed air supply and disassemble the Air Knife. If dirt is present, clean all of the component parts and reassemble without installing a thicker shim (or additional shims). If all parts appear to be clean, we suggest that you install a shim of the next higher thickness since this can produce a dramatic change in air volume and velocity. Be sure to tighten each screw snugly (7.5 ft/lbs). We suggest that the shim thickness be increased by .001" (.03mm) increments until the desired performance is achieved.

The longest one piece Super Air Knife that we stock is 108". For applications requiring Air Knives longer than that, multiple Super Air Knives can be connected end to end with the Super Air Knife Coupling Bracket Kit, which produces a laminar, even, uninterrupted flow of air, from end to end, as long as you need. If you require a non-stock length Super Air Knife, EXAIR will make Air Knives in any length you want. We ship most orders for special length Air Knives in 3 Days after receipt of order.