EXAIR Super Air Knife: Overview

 

Loud and inefficient homemade blowoff

Drilled pipes, like the one shown above, are all too common in industrial settings for processes where a wide surface area needs to be treated. Their popularity can be attributed to how cheap and easy they are to make but in actuality they are very expensive to operate, as they waste large amounts of compressed air, and are very dangerous to operate.

We frequently take calls from customers looking for a more energy efficient, safer solution to replace these types of blowoffs. EXAIR manufactures 3 different styles of Air Knife – the Super, Standard and Full-Flow – that are the ideal solution for wide coverage applications. Today, I would like to provide an overview of our award wining Super Air Knife.

The Super Air Knife

The Super Air Knife is our most efficient air knife in regards to compressed air usage, using only 2.9 SCFM per inch of knife length @ 80 PSIG. It is also the quietest on the market today at only 69 decibels. The Super Air Knife provides the highest air velocity of the 3 styles offered by EXAIR and produces 2.5 ounces of force per inch at 80 PSIG operating pressure. We offer stock lengths from 3” up to 108” in single piece construction with available materials of aluminum, 303ss and 316ss. We also offer PVDF (Polyvinylidene Fluoride) up to 54” for harsh environments.

The Super Air Knife provides a laminar airflow across the entire length with hard-hitting force. They also give a 40:1 amplification rate meaning they entrain 40 parts of the surrounding room air for every 1 part of compressed air used, producing a large volume outlet flow.

Coupling Kit for the Super Air Knives

For applications requiring an air knife length longer than 108″, we offer a coupling bracket kit that allows you to connect two Super Air Knives together for a seamless, uninterrupted flow. Kits are available in aluminum, 303ss or 316ss to match the construction of the knife.

In addition, we also offer plumbing kits as an accessory item. For aluminum Super Air Knives, we offer cut to length nitrile/PVC hose and brass fittings and for stainless steel and PVDF knives we offer 316ss cut-t0-length pipe and fittings.

If you have any questions on how the Super Air Knife might fit into your process, please contact an Application Engineer.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Proper Supply Line Size And Fittings Provide Peak Performance

Many times when we provide the air consumption of an EXAIR product, we get a response like…. “I’ve got plenty of pressure, we run at around 100 PSIG”. While having the correct pressure available is important, it doesn’t make up for the volume requirement or SCFM (Standard Cubic Feet per Minute) needed to maintain that pressure. We commonly reference trying to supply water to a fire hose with a garden hose, it is the same principle, in regards to compressed air.

When looking to maintain an efficient compressed air system, it’s important that you use properly sized supply lines and fittings to  support the air demand (SCFM) of the point-of-use device. The smaller the ID and the longer the length of run, it becomes more difficult for the air to travel through the system. Undersized supply lines or piping can sometimes be the biggest culprit in a compressed air system as they can lead to severe pressure drops or the loss of pressure from the compressor to the end use product.

Take for example our 18″ Super Air Knife. A 18″ Super Air Knife will consume 52.2 SCFM at 80 PSIG. We recommend using 1/2″ Schedule 40 pipe up to 10′ or 3/4″ pipe up to 50′. The reason you need to increase the pipe size after 10′ of run is that 1/2″ pipe can flow close to 100 SCFM up to 10′ but for a 50′ length it can only flow 42 SCFM. On the other hand, 3/4″ pipe is able to flow 100 SCFM up to 50′ so this will allow you to carry the volume needed to the inlet of the knife, without losing pressure through the line.

Pipe size chart for the Super Air Knife

We also explain how performance can be negatively affected by improper plumbing in the following short video:

 

Another problem area is using restrictive fittings, like quick disconnects. While this may be useful with common everyday pneumatic tools, like an impact wrench or nail gun, they can severely limit the volumetric flow to a device requiring more air , like a longer length air knife.

1/4″ Quick Connect

For example, looking at the above 1/4″ quick disconnect, the ID of the fitting is much smaller than the NPT connection size. In this case, it is measuring close to .192″. If you were using a device like our Super Air Knife that features 1/4″ FNPT inlets, even though you are providing the correct thread size, the small inside diameter of the quick disconnect causes too much of a restriction for the volume (SCFM) required to properly support the knife, resulting in a pressure drop through the line, reducing the overall performance.

If you have any questions about compressed air applications or supply lines, please contact one of our application engineers for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Video Blog: Super Air Knife with Plumbing Kit Installed

 

This short video features our new Stainless Steel Plumbing kits. Ordering a Super Air Knife with the Plumbing Kit installed, provides the best performance and makes for an easy installation.

 

 

Please contact an application engineer for assistance @ 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Plumbing Kits Simplify Air Knife Installation

Incorrect plumbing is an all too common problem we deal with on a regular basis here at EXAIR. Many times we receive calls from a customer saying that their Air Knife isn’t producing a high velocity or they are seeing an uneven airflow. In fact we have written many blogs touching on this subject, such as the one I posted a few weeks ago titled, Proper Air Supply & Installation Provides Best Performance or the one titled Typical Compressed Air Plumbing Mistakes by our International Application Engineer John Ball.

Using undersized supply lines can cause excessive pressure drops because they aren’t able to carry the volume of air necessary to properly supply the compressed air device. We commonly reference trying to supply water to a fire hose with a garden hose, it is the same principle. Using restrictive fittings, like quick disconnects, will also contribute to this effect as the ID of the fitting is much smaller than the NPT connection size. Example: Say you are seeing 80-100 PSIG upstream of  an air knife at the pressure gauge, by the time the air passes through a quick disconnect or small ID line and fitting, the actual pressure being delivered to the unit will be much less, possibly as low as 20-30 PSIG depending on the installation. One way to measure the actual pressure being delivered to the air knife would be to install a pipe tee with a pressure gauge right at the inlet of the air knife.

All of our products are shipped with an installation guide referencing the proper recommended pipe sizes for various lengths of supply pipe. When dealing with our Air Knives, since we offer lengths up to 108″, you need to plumb air to multiple inlets for knives that are 24″ and larger. To simplify the installation process, we offer our Air Knife Plumbing Kits. The Plumbing Kits include properly sized nitrile/PVC compressed air hose and brass fittings for our aluminum units. In addition, we now offer 316ss pipe and fittings for our stainless steel and PVDF Super Air Knives for applications requiring superior corrosion resistance. Using the plumbing kits eliminates pressure loss and the need for searching for the proper fittings or possibly using incorrect pipe size.

Aluminum Plumbing Kit
Plumbing Kit for aluminum Super Air Knife

 

SS Plumbing Kit
Plumbing Kit for Stainless Steel and PVDF Super Air Knife

 

If you think you are experiencing less than expected performance from one of our products, please give us a call so we can help.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

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(Im)Proper Infeed Pipe Size For The Super Air Knife

Last week I took a call from a customer stating their 54” Super Air Knife was, “Barely producing any output flow or increase in velocity”, thus they wanted to adjust the gap in the air knife by adding shims to try and increase their output. I explained that by adding more shims, they were only going to increase their air demand (which was already exceeding supply) and lessen the output velocity.

I decided to take another approach, so instead of just taking the sale for more shims, we began to troubleshoot the issues they were experiencing. 

After a brief discussion with the customer, I asked if they could take a picture of the process application and send via email. Below is the image that was sent…

 Hudson Ranch SAK 54inch installation

After reviewing the image it was determined there were a few issues with the installation of the Super Air Knife, with the main concern being the in-feed pipe size and connection. The customer was using ¼” O.D. tubing and a quick disconnect which was actually “starving” the Super Air Knife and causing severe pressure drops. You can also explain in this way, it’s like feeding a fire hose with a garden hose, the smaller hose just can’t provide enough volume of water for the larger hose to spray the water out at a high volume and velocity. 

 

Super Air Knife recommended input air line size

 

EXAIR provides a chart explaining what size we recommend for compressed air supply lines into our products within our installation and maintenance guides. Per the above chart, for our 54” Super Air Knife we recommend a 3/4” in-feed pipe size for a 10’ length of run, 1” pipe size for 50’ and 1-1/4” pipe size for 100’. Also, you should not use restrictive fittings, such as quick disconnects, which will cause excessive air volume lost, resulting in pressure loss through the Knife.

If you are having a similar issue or believe you are getting sub par performance from your EXAIR product, please do not hesitate to contact an Application Engineer at 1-800-903-9247 for assistance, we are confident that we can get it up and running to solve your application. 

Justin Nicholl
Application Engineer
justinnicholl@EXAIR.com
@EXAIR_JN

 

 

 

Dude, Where’s My Air Pressure?

The question comes up every so often. “I have 10 BARG plant pressure, but can only get 2 BARG pressure on the gauge at your Chip Vac.  What is the problem?”

We call the problem “pressure drop”. And pressure drop is attributed to many things. All of them have to do with the delivery of the compressed air supply up to the point of use or product.  In this case, the product was EXAIR’s 5 Gallon Chip Vac Model 6193-5. We found that actually having a pressure gauge installed right at the inlet of the Chip Vac vacuum generating part itself help greatly for the customer to realize the nature of their problem. The sources of such problems are usually to do with the diameter of the compressed air line feeding the “device” being too small. You will probably note in the photo that the customer has installed a 6 mm inside diameter line with a quick connect fitting. Upon further questioning of the customer, this supply line was 10 meters (33 ft) long. The Chip Vac requires 33 SCFM @ 80 PSIG (934 SCFM @ 5.5 BARG) to operate as advertised. Note this is the requirement at the inlet. Where you measure pressure in a compressed air system is of utmost importance. And for any compressed air consuming device, that value is going to be as used at the inlet, not at the wall or wherever the compressed air drop may be located.

Once the customer was able to increase to a 12 mm ID line and cut the length down to about 5 meters, the Chip Vac performed as intended. This was because it was no longer starving for compressed air through the smaller line.

We notice that many customers will try to get away with using too small a diameter of compressed air line. Perhaps it is what they had on hand or it was cheap to get. The problem is they end up shooting themselves in the foot when it comes to performance of the product connected out at the point of use.

By taking the time to practice proper plumbing technique, one can save themselves a lot of headache when setting up any pneumatic equipment. Of course, if you need advice on what the proper line size needs to be for any given installation, give us a call. We’ll be glad to assist you.

Neal Raker, Application Engineer
nealraker@exair.com