Tag: air curtain

Understanding Air Entrainment or Amplification Ratios and Air Knives

Published on by EricKuhnash@EXAIR.comLeave a comment
Super Air Knife has 40:1 Amplification Ratio, entrainment is illustrated as the curved blue arrows.

EXAIR’s Super Air Knife is the top performer among our engineered air knives and it dramatically reduces compressed air usage and noise when compared to other blow-off systems. The Super Air Knife delivers a uniform sheet of laminar airflow across the entire length of the air knife. Even at high pressure of 80 PSIG (5.5 BAR), the sound level is surprisingly quiet at 69 dBA for most applications.

One feature of the Super Air Knife is its Amplification Ratio, or the ratio of ambient air to compressed air within the forceful blast of air from the Super Air Knife. The design of the Super Air Knife entrains ambient air at an amplification ratio of 40:1 (ambient air to compressed air). Entrainment is defined in the simplest of terms as: to draw in and transport (something, such as solid particles or gas) by the flow of a fluid. The Super Air Knife design produces two low pressure areas where surrounding air is pulled into the primary compressed air stream and is delivered to your target. EXAIR’s Intelligent Compressed Air® products use the principle of entrainment to give you more air volume than just the compressed air being introduced from your air compressor.  This will maximize the force value for your application with the minimum amount of compressed air. Any pipe, manifold, or fitting can be modified to blow compressed air, however, these homemade blow offs will be very noisy and perform poorly when it comes to air entrainment, or amplification ratios. In contrast EXAIR’s intelligent compressed air solutions are engineered to be very quiet and use conservative amount’s of compressed air while maximizing the output volume through entrainment. 

Furthermore, the table below demonstrates the differences between blow-off systems and the efficiency of EXAIR’s Super Air Knife. You can see that the Super Air Knife outperforms all or most other options when comparing purchase price, sound level, maintenance, horsepower required and electrical costs.

The use of EXAIR’s Super Air knife not only save air consumption but you can notice the lower decibel rating which meets or exceeds OSHA Standard 29 CFR-1910.95(a) for maximum allowable noise exposure. If you have questions or need help with EXAIR’s Super Air Knife or any of our Intelligent Compressed Air Products please contact us and let us help you.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@exair.com
Twitter: Twitter: @EXAIR_EK

Adjust Force and Air Consumption with Super Air Knife Shim Sets

Published on by Tyler DanielLeave a comment

EXAIR’s industry leading Super Air Knife dramatically reduces compressed air usage and noise when compared to other blowoff methods. The Super Air Knife is available in lengths ranging from 3”-108” and in Aluminum, 303 Stainless Steel, 316 Stainless Steel, and PVDF for corrosive applications. Even at high pressures of 80 psig, the Super Air Knife is able to maintain a sound level of just 69 dBA for most applications! Air is entrained from the ambient environment at a rate of 40:1, maximizing the force and flow from the Super Air Knife. In addition, these knives meet or exceed OSHA maximum dead-end pressure and noise requirements.

completeAirknifesets
From left to right – plastic shims, SS shims, PTFE shims.

Adjustability of both the force and flow from the Super Air Knife has a huge range of adjustability. Right out of the box from the factory the Super Air Knife comes stock with a .002” thick shim installed. This sets the gap between the body and cap of the knife and determines how much compressed air can flow through the precise, slotted orifice. An accessory that EXAIR has available for the Super Air Knife is the shim set. For the aluminum knives, a .001”, .003”, and .004” plastic shims come in the shim set. To reduce the flow and force, a .001” can be used. If more force is required, a thicker shim can be installed. For the stainless steel and PVDF knives, (3) .002” shims are included in the set. Stainless steel shims for the stainless knives and a PTFE shim for the PVDF. These, as well as the plastic shims, can be stacked on top of one another to create an even larger gap. One thing that is important to keep in mind however, the larger the air gap the greater the air consumption. Installing a .004” shim in a Super Air Knife will double the flow and consumption of the knife when compared to the stock .002” shim.

Installing a new shim in your Super Air Knife is very simple to do. Check out this quick video from Neal Raker that walks you through the steps:

While the different shims are available for you to make gross adjustments to the force and flow of your Super Air Knife, there is one additional method. By using a pressure regulator, you can fine-tune the input pressure that is supplied to the Super Air Knife. This will also greatly impact the force and flow. At 40 psig, the Super Air Knife will consume 1.7 scfm/inch and provide 1.1 oz/inch of force. At 80 psig, it will consume 2.9 scfm/inch and provide 2.5 oz/inch of force. EXAIR offers pressure regulators in a variety of different sizes to accommodate any of our Super Air Knives from 3” all the way up to 108”.

If you’re wasting air in your facility using cheap nozzles, drilled pipes, or any other inefficient solution give us a call. An Application Engineer will gladly investigate your application and help to design a better, safer, and more cost-effective solution!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

Why Use Compressed Air Knives – Super Air Knives and their Options

Published on by Jordan T ShouseLeave a comment

EXAIR has been manufacturing Intelligent Compressed Air® products since 1983.  In the beginning, the Standard Air Knives and Full Flow Air Knives were very effective at that time.  But as leaders in this market, EXAIR did not want to stop there.  We were able to engineer a more efficient, more powerful, and safer air knife, the Super Air Knife.  In this blog, I will discuss the features and benefits that the Super Air Knives can offer. 

Bernoulli’s principle explains how a high velocity fluid can generate a low pressure.  The Super Air Knife creates that high velocity air stream to produce a low pressure above and below the opening to entrain ambient air.   What does this mean for you?  The low pressure entrains the surrounding ambient air, adding it into the total airflow, and uses less compressed air.  The mass of the free ambient air is added into the air stream to give a strong blowing force.  The Super Air Knife has an amplification ratio of 40:1. For every 1 part of compressed air, 40 parts of ambient air is drawn into the blowing air stream.  Ambient air is free, and compressed air is definitely not.  EXAIR was able to engineer a design, using Bernoulli’s principle, to make the most efficient air knives in the marketplace.   

Super Air Knife

Another benefit is they blow a laminar air stream which reduces noise levels and create a consistent force along the entire length.  An even force will give you tighter control for blowing applications which will cut compressed air usage unlike the inconsistent and turbulent air flows caused by drilled pipes, manifolds of nozzles or blower-type systems.  Some other interesting features for the Super Air Knives are that they have a compact design to fit into tight places for blowing and cooling.  The footprint is very small as compared to blower-air knife systems.  They do not have any moving parts to wear or maintenance to do.  They only need clean compressed air to work. 

What else makes the Super Air Knives unchallenged?  We manufacture and stock the widest range in lengths and materials.  To start, Super Air Knives range from 3” to 108” (76mm to 2,743mm) in three different materials; aluminum, 303 stainless steel, and 316/316L stainless steel.  There is no-one else in this industry that can manufacture to those lengths.  EXAIR also offers Super Air Knives in PVDF material with Hastelloy hardware for chemical resistant applications from 3” to 54” (76mm to 1,372mm).  Depending on the temperature requirement, chemical resistance, OSHA and FDA regulations, or application details, we are confident there is one on the shelf for your application. IF you order by 2pm, EXAIR will ship same day.  

If EXAIR does not stock it, we make special air knives in different lengths and materials to best fit your application.  In some confined areas, the Super Air Knives may have to fit inside a specific width or footprint.  Well, EXAIR can make it to that specific width in a short period.  We have also made special designed Air Knives that were very thin, curved, double-sided, and with distinct mounting holes to easily attach to specific machines or operations.  And if you need a special material, like the PVC Super Air Knife below, we can do that.  EXAIR has a team of Application Engineers that can help you with the design, configuration, and details for special types of Super Air Knives. 

PVC Super Air Knife
Double-sided Super Air Knife

We also offer the Super Air Knives in kits as a more complete system.  The kit includes a filter, regulator and a Shim Set.  The filter removes the debris and water from the compressed air line to optimize the performance of the air knife as well as keeping your product clean.  The regulator is used to make the “fine” adjustment to the blowing force while the shim set is used as the “coarse” adjustment.  EXAIR sells this kit as one model number for simple ordering, and the accessories are properly sized to not hinder the performance of the Super Air Knife.

Super Air Knife Kits include a Shim Set, Filter Separator, and Pressure Regulator.

With the today’s cost to make compressed air, it is important to do it as efficiently as possible.  The EXAIR Super Air Knives are the most efficient as well as safe and effective.  And if you need a specific design for your application, you can contact an Application Engineer at EXAIR.  We will be glad to help you. 

Jordan Shouse
Application Engineer

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Replace Homemade Blowoffs with Engineered Solutions for BIG savings

Published on by Brian FarnoLeave a comment

Saving money on compressed air is as simple as replacing current, inefficient products with engineered products which are made to be efficient and OSHA safe (for noise and dead end pressure).

Sections of pipe with drilled holes along the length are a common find in industrial environments as they are made of relatively inexpensive materials and simple to make.  Where the cost begins to add up is on the operation side as these types of homemade blow-offs waste a ton of compressed air offsetting their cheap purchase price and making them expensive to operate.

For comparison, lets look at a 12″ section of pipe with (23) 1/16″ diameter drilled holes. Referencing the table below, each hole will flow 3.8 SCFM @ 80 PSIG for a total of 87.4 SCFM.

With an average cost of $ 0.25 per every 1,000 SCF used (based on $ 0.08/kWh), it would cost $ 1.31 to operate this blowoff for 1 hour. (87.4 SCFM x 60 minutes x $ 0.25 / 1,000)

Now let’s run the numbers as if we look at replacing the drilled pipe with our 12″ Super Air Knife. A 12″ Super Air Knife will consume 34.8 SCFM (2.9 SCFM per inch) when operated at 80 PSIG. Using the same figure of $ 0.25 per every 1,000 SCF used, it would cost $ 0.52 / hr. to operate this knife. (34.8 SCFM x 60 minutes x $ 0.25 / 1,000)

Just to better lay these out, let’s review the operating costs.

Drilled pipe operating costs:
$ 1.31 per hour
$ 10.48 per day (8 hours)

12″ Super Air Knife costs:
$ 0.52 per hour
$ 4.16 per day (8 hours)

Cost Savings:
$ 10.48 per day (drilled pipe) –  $ 4.16 per day (Super Air Knife) = $ 6.32 savings per day

Over the course of one year, one shift per day, and 250 working days per year – the Super Air Knife saves $1580 annually. Obviously, that will increase if you are running more than one shift, or have multiple blow-offs in place.

While the drilled pipes always appear to be a quick an easy solution that carry low cost of ownership, remember to look at the total cost of operation. This is where engineered solutions surpass their drilled hole alternative.

If you would like to discuss drilled pipes within your facility or want to see how an engineered solutions may fit the needs you see, contact an application engineer today.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF