Super Air Knife Math – When 72 + 72 = 75

The Super Air Knife is the latest generation of EXAIR engineered air knife that dramatically reduces compressed air usage and noise when compared to other blowoffs.

Super Air Knife Data

From the chart above, the Super Air Knife when supplied with 100 PSIG of compressed air has a sound level of just 72 dBA (A-weighted decibel scale) when measured from 3′ away.  72 dBA is a moderate sound level, and some common comparisons are ‘normal speaking voice’ at 70 dBA and ‘living room music’ at 76 dBA.

For many processes, such as a bottling line drying operation, a pair of the air knives delivers the best performance. When asked, “what is the sound level for (2) of the knives,” a little Acoustic Engineering is in order. Because the decibel scale is logarithmic, the result is not as simple as adding 72 + 72 = 144.  144 dBA is in the range of a jet aircraft take off! Thankfully, both the actual sound level and the numerical value are determined another way.  I’ll spare you a lot of the math but the equation is as below.

Capture

… where SL1, SL2, SL3 are the sound levels in dBA of the each sound makers, for as many that are being combined.

In the case of (2) Super Air Knives operated 100 PSIG, the combined sound works out to be a quiet 75.0 dBA — a powerful, efficient and quiet product ideal for many applications and process within the manufacturing environment.

Super Air Knife

Super Air Knife

As a helpful rule of thumb- combining any (2) items will yield an increase of 3 dBA, combining (3) results in a rise of 4.8 dBA, and combining (4) results in a 6 dBA rise over just (1) of the items.

The Super Air Knives have been successfully used in a wide range of applications, including part drying, sheet and conveyor cleaning, web cooling, scrap removal, pre-paint dust blowoff, and many, many more.

To discuss your application and how an EXAIR Intelligent Compressed Air Product can make your process better and quieter, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Excessive Noise Levels Cost You Health and Money

OSHA and the CDC make these statements about noise exposure. Did you know almost 30 million American workers are exposed to dangerous noise levels almost daily, with over 72% of those reported incidents happening in manufacturing environments? Noise induced hearing loss is the second most self-reported occupational injury and since 2004, over 125,00 workers have experienced some level of permanent hearing loss. Excessive noise levels can also reduce productivity, contribute to increased stress levels, communication errors and an irreversible condition called tinnitus or a constant ringing in the ears. In fact, disability claims associated to occupational hearing loss has risen to over $ 242 million per year.

30mill

Noise Induced Hearing Loss Is One Of The Most Common Occupational Diseases.

In effort to reduce worker exposure and increase safety, OSHA introduced Standard 29 CFR 1910.95(a). As the standard reads, employees that are subjected to sounds levels in excess of 90 dBA, some type of engineered controls should be implemented by either using some form of PPE – Personal Protective Equipment, i.e. – earplugs, earmuffs, etc. or replacing the loud device altogether with an engineered solution that is designed to reduce the sound level. When a company is found to be in violation of the Standard, OSHA hands down costly fines, in some cases nearing almost $5,000. While providing PPE may seem like the inexpensive, “quick” fix, it actually could lead to more overall cost in the form of fines or claims, as now it is the responsibility of the operator to utilize the equipment provided. The better choice of the 2 options mentioned above, would be to replace with an engineered solution that is designed to lower the sound level.

OSHA Noise Level

Noise Level Chart per OSHA Standard 29 CFR 1910.95(a)

Take for example, a section of pipe with drilled holes across the length to cover wide area applications or an open end pipe or tube for more focused blowoff, both of which typically produce sound levels in excess of 100 dBA which would limit work exposure to only a couple hours per the above chart.

EXAIR’s Intelligent Compressed Air Products are designed to meet or exceed this standard. Our products entrain large volumes of surrounding air across the profile of the device which helps to reduce wind shear, ultimately lowering the sound level. When considering replacing drilled pipe, take a look at our Super Air Knife. The Super Air Knife produces a much lower sound level at only 69 dBA which is well under the allowable exposure times set forth by OSHA. Depending on the pipe or tube size, these can quickly and easily be replaced with one of our Super Air Nozzles by just adding a fitting to the existing line. For instance, our Model # 1100 Super Air Nozzle, with a sound level of 74 dBA, again falls well within the OSHA Standard.

sound-level-comparison

Sound Level Comparison

In addition, we offer our Digital Sound Level Meter to measure sound levels ranging from 35 to 130 dBA. The unit features a backlit LCD display, fast and slow response times, Max hold and includes NIST (National Institute of Standards and Technology) certification.

SoundMeter_new_nist225

Model 9104 Digital Sound Level Meter

For assistance in gaining OSHA compliance relating to your compressed air needs, please give us a call.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

 

 

EXAIR’s High Velocity and Adjustable Air Jets – Now Available in Stainless Steel

Newly released, the EXAIR High Velocity Air Jet and Adjustable Air Jet are now available in Type 303 Stainless Steel, providing greater durability, corrosion resistance and a higher maximum temperature rating of 400 °F.  Type 303 stainless steel has good resistance to mildly corrosive atmospheres along with good oxidation resistance at elevated temperatures, making the stainless steel Air Jet a great choice for blowoff or part drying in your harsh environment. Both types of Air Jets are also available in brass, for applications at 275°F and below, and when corrosion resistance is not as critical.

6013ss

Model 6013SS – High Velocity Air Jet

Air Jets utilize the Coanda Effect – wall attachment of a high velocity fluid – to produce air motion in their surroundings. As illustrated above, a small amount of compressed air to the inlet (large black arrow) is throttled through an internal ring nozzle above sonic velocity.  A vacuum is produced, resulting in large volumes of surrounding, or “free” air, being pulled in through the jet (blue arrows.)

air jet How Air Jets Work

Both the outlet and inlet can be ducted for remote positioning applications.

If the end is blocked, flow simply reverses at well below OSHA dead end pressure requirements, ensuring safe operation.

The High Velocity Air Jet comes standard with an .015″ shim, and a Shim Set is offered that includes .006″ and  .009″ shims to provide additional adjustability and control.  The Adjustable Air Jet has a variable gap design, and can be adjusted and locked to meet the required airflow and thrust parameters.

When you are needing a simple solution to reduce excessive air consumption and noise levels on compressed air blowoff operations, EXAIR has a large line of Air Nozzles and Jets to solve your problems. You can contact an Application Engineer to discuss which Air Jet or Nozzle to best fit your application.

Brian Bergmann
Application Engineer

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Compressed Air Gun’s Many Forms Solve Many Problems

Have you just glanced around your manufacturing plant? You usually always see either the “curly” yellow hose or a red rubber hose with an air gun attached to it.  They hang at work stations, machines, packaging areas, and even in obscure places.  The reason that I bring this up is for safety reasons.

Recently we had a medium-sized manufacturing plant that was audited by OSHA. One of the first violations that OSHA found was with their compressed air guns with the typical brass pipe with the hole going through the side (one of the most typical types of nozzle).  It violated code 29 CFR 1910.65(a) for maximum allowable noise exposure.  The company had to make a choice to either purchase hearing protection for the operators or to find an alternative product.  They contacted us because we could reduce their noise level.  I suggested a Super Air Nozzle, model 1100 for their application.  When they attached our Super Air Nozzle into their air gun, they quickly heard the difference with the low noise.  With the added benefits of quality, high force, and meeting all the safety requirements, they decided to purchase the nozzles with our Safety Air Guns.  They ordered 90 pieces of our Soft Grip Safety Air Gun with Chip Shield, model 1210-CS.  This took care of the OSHA violation, and the operators were very happy with the product.

Model 1210-CS

Model 1210-CS

Another company was using compressed air with a ¼ turn valve attached to a 36” (91 cm) copper tubing. They used this device to reach into areas to blow off chips.  The Safety Compliance Officer was familiar with OSHA 29CFR 1910.242(b).  The regulation references chip shields and using pressures below 30 psig (2 bar).  Compressed air can enter the blood stream through the skin with pressures above 30 psig (2 bar) in a dead-end occurrence.  To keep his workers safe, he mandated a maximum supply line pressure of 30 psig (2 bar) throughout the plant.  This increased the cleanup time for an operation as the force was reduced greatly.  The Safety Compliance Officer contacted us about our Safety Air Guns.  I explained that with our nozzles, they are engineered to operate at higher supply line pressures and still be below the dead-end pressure requirement of 30 psig (2 bar).  With our design, it keeps the surface of your skin from blocking the air openings, like you can do with a copper tubing.  They ordered 25 pieces of our Heavy Duty Safety Air Gun with a 36” (91 cm) extension and Chip Shield, model 1310-36-CS.  The operators were happy with the durability of the gun and with the ability to increase the air pressure for faster cleaning.  The Safety Compliance Officer was happy to meet the OSHA standard and to keep his workers safe.

Model 1310-36-CS

Model 1310-36-CS

EXAIR offers a variety of different types of nozzles and Safety Air Guns to fit the requirements of your applications. All of our nozzles are safe, quiet, and powerful.  We offer them in different materials from aluminum/zinc, stainless steel, and PEEK.  They are designed to entrain ambient air to save compressed air and money.  As a note, an air gun is only as good as the nozzle it is using.  Many air guns come with a very inexpensive brand of nozzle.  They are typically very loud and very inefficient.  I always like to use the analogy of a paint sprayer.  No matter how good the spray gun is, if you have a poor nozzle, you will end up with many flaws in your paint.  The same can be said with compressed air guns.

To keep your company compliant and safe, you can always contact an Application Engineers to help pick the correct product for you.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

A Sound Reckoning Of The Super Air Knife

In May of 1976, The Who performed a concert in London that Guiness’ Book of World Records used to certify them as the World’s Loudest Band. A sound level of 126 decibels was recorded and documented at a distance of 32 feet from the stage. That’s right at the boundary of the threshold of pain.  Which I’m sure is what they were going for.

There are a variety of charts available that relate common noises to the decibel levels they could be expected to produce. For instance, a DC-9’s engines produce a sound level of about 120 decibels at takeoff or landing. Now, imagine if such a plane were to land at the aforementioned concert: would the sound level, at a given distance, be equal to those two decibel levels added together?

The answer, of course, is no, because we’re talking about sound pressure level. It’s not EXACTLY the same as fluid pressure, but a decent analogy is that, if you have an air compressor supplying your system with 100psig compressed air, turning on your other, identical air compressor won’t result in 200psig in your system.

I mention this for a couple of reasons. One; I’m a BIG fan of The Who, and I heard one of my favorite songs of theirs on the radio this morning: “You Better You Bet,” from their Face Dances album, which came out in 1981 and hence would not have been played at the 1976 Loudest Band concert, but I digress.

The other reason is because of a conversation I had with a caller about the sound levels produced by our Super Air Knives. The published sound pressure level is 69 dBA. “dB” is short for decibels; “A” means the unit is weighted to express the relative loudness of sounds as perceived by the human ear. Anyway, the caller was interested in knowing how much louder our longer Super Air Knives were than their shorter counterparts. The answer is, of course, they’re not louder…for the same reason that your second air compressor doesn’t double the air pressure in your system, which is the same reason that the fictional jet landing at the rock concert wouldn’t double the sound level.

Now, a couple of things to consider: the sound pressure levels that we publish were measured at a distance of 3 feet to the side of the Super Air Knife. Sound levels at a closer distance, and/or in front of or behind the Air Knife, will be different. Also, the Super Air Knife was blowing into free air. If the air flow is impinging on a surface, there will be a sound level associated with that as well. If it’s in excess of the 69 dBA that the Super Air Knife is producing, then that’s what your ears are going to be subject to.

All things considered, though, the Super Air Knife is INCREDIBLY quiet, considering the amount of air flow it’s producing. The science behind this has to do with what makes them so efficient with their use of compressed air: their entrainment ability. The Super Air Knife’s design allows it to use the primary compressed air flow to entrain enormous amount of air from the surrounding environment. This entrained air not only multiplies the resultant flow rate produced, but forms an attenuating boundary layer, which effectively reduces the sound level produced by the high velocity compressed air.

The Super Air Knife entrains air at a rate of 40:1, relative to its compressed air consumption.

The Super Air Knife entrains air at a rate of 40:1, relative to its compressed air consumption.

If you’d like to find out more about how EXAIR Intelligent Compressed Air Products such as the Super Air Knife can reduce your air consumption AND your sound levels, give me a call.

Russ Bowman
Application Engineer
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Video Blog: Features and Positioning of EXAIR’s Digital Sound Level Meter

This video explains a few of the features on the EXAIR Digital Sound Level Meter. It also illustrates proper positioning of the meter when taking sound level readings. This sound level meter is an important tool to quantify noise exposure of employees and identifying the sources of noise.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Reduce Noise Exposure with Super Air Nozzles

News from the CDC that those of us involved with industrial safety are paying close attention to is the release of their NIOSH (National Institute for Occupational Safety and Health) division’s Hazard Evaluation Program Noise Measurement Database, which contains data obtained through Health Hazard Evaluation surveys performed between 1996 and 2012. It includes hundreds of personal noise exposure measurements (how much noise was received by individuals) and almost as many area noise measurements (how much noise was made.) A comparison of these measurements, of course, is valuable in determining if appropriate measures are being taken to abate the exposure, which is key: there are an awful lot of industrial processes where there’s nothing that can be done about the generation of noise…they’re just simply LOUD. So, they focus on what they can do to limit exposure: Use engineering controls (retrofit open line with engineered nozzles, build sound barriers) , use administrative controls (relocating personnel away from the sound), use personal protective equipment, and spending as little time as possible near the source.

Regardless of what people can get used to, the area noise associated with compressed air use CAN be reduced, while still maintaining the efficiency of the operation. Here’s the deal:

*The most basic form of air blow off is a piece of pipe, tubing, or hose connected to a source of compressed air. When it’s opened to the atmosphere, the compressed air exits with a great deal of force. This makes quite a racket, and the only way to quiet it down is to reduce the air supply pressure. Then you get less force, however, and it might not get the job done.

*Engineered air nozzles, such as EXAIR’s Super Air Nozzles, solve this problem by design:

air nozzle flow

The compressed air supply (black arrow) uses the Coanda effect when it exits the series of holes recessed in the array of fins (dark blue arrows.) This serves to entrain an enormous amount of air from the surrounding environment (light blue arrows,) which not only results in a high volume flow rate at minimal consumption, but also makes the resultant air flow very quiet.

EXAIR Super Air Nozzles are quiet, efficient, and easy to get…we maintain inventory of anything you see in the Catalog, all available for same day shipment. If you’d like to know how EXAIR products can be easy on your ears…and your wallet…give me a call!

Russ Bowman
Application Engineer
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax
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