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 Efficiency Lab can Help With your Energy Audit, Quantify Savings and Provide an ROI

I recently received an inquiry from a customer to test their current air guns through our Efficiency Lab service. According to the operators, the handheld blow gun they were purchasing from a commercial retailer was too loud and complaints were rolling in.  They were also hoping to save some compressed air in the process as they were performing an energy audit at the same time.

Commercial Air Gun w/ Cross Cut Hole

Commercial Air Gun w/ Cross Cut Hole

Cross Cut Hole Nozzle

Cross Cut Hole Nozzle

The gun they sent in looked fairly similar to our Precision Safety Air Gun but it did not have an engineered nozzle on the tip of it.   Instead, it was simply a cross cut hole in a piece of material.   The air inlet to the gun was a 1/4″ NPT just like our Precision Safety Air Gun, the extension on the gun was slightly longer, the only significant variance I saw was the tip.

EXAIR Model 1410SS-CS

EXAIR Model 1410SS-CS

The Model 1110SS Nao Super Air Nozzle and Chip Shield

The Model 1110SS Nao Super Air Nozzle and Chip Shield

To try and get as much information as possible I measured the O.D. and I.D. of the extension, the hole size was approximately .140″.  I measured the extension on our Precision Safety Air Gun just to see what is different, it came in at the same size.  So, I flow tested the competitive blow gun with their tip on it and came up with air consumption of 12.69 SCFM, noise level of 92 dBA at 3′ away, and a blowing force of 11.5 oz at 80 psig.   I then measured the same attributes of EXAIR’s model 1410SS-CS Precision Safety Air Gun at 80 psig inlet pressure.  The model 1410SS-CS measured 8.3 SCFM, gave 8.1 ozs of working force, and only produced a 75 dBA sound level from 3′ away.

The sound level reduction was a total of 17 dBA which is below the OSHA standard for allowable noise level exposure, as well as reduced their air consumption by 4.39 SCFM.  That is almost a 35% reduction in their compressed air usage per gun replaced.  After seeing these levels of reduction the customer had more than enough information to provide management with in order to replace the blow guns not just for noise level reduction but also because it will reduce air use and save money. A clear supportive role in their energy audit.

If you would like to discuss how EXAIR can provide some free force, flow, and noise level testing for your facility, please contact an Application Engineer or check out the Efficiency Lab page on our site.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

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

How to Meet the OSHA Compressed Air Standard

Every day we talk to customers who need to comply with OSHA regulations for using compressed air to clean up their shop or product. Back in 1972 on Valentine’s Day, OSHA published Directive Number STD01-13-001 standard 1910.242(b), which strives to provide guidance on how manufacturers can safely use compressed air for cleaning purposes to comply with the Walsh-Healey Act of 1936.  This directive laid out acceptable methods for complying with 41CFR 50-204.8 and 29 CFR 1910.242(b)

The two methods are very simple, but still many people have questions.  The first method (pictured below) is to regulate the line pressure from the compressor to below 30 PSIG.

Regulator Method

Figure 1 Regulator method Photo Courtesy of osha.gov

The second method is to install a nozzle engineered to reduce the static pressure of the nozzle to less than 30 PSIG.

OSHA Nozzle Method

Figure 2 Nozzle method Photo Courtesy of osha.gov

The first method reduces the danger by limiting the energy in the system to less than an amount which can injure a person.  OSHA determined that 30 PSIG was the safe limit for the amount of pressure the human body could withstand without causing severe injury. The problem with this method is that cleaning with compressed air at 30 psig is virtually impossible.  Which means at such a low pressure the operator must pass the nozzle so close to the chips and debris, he might as well use a broom or pick each piece of debris up with his fingers. This first method I will label the regulator method. The second method introduces a relief valve at the nozzle, so that an operator cannot block off all of the openings of the nozzle, and build up any static pressure on their skin. I will call this the nozzle method.

Commonly and cheaply, the nozzle method is done by cross drilling a hole in an open pipe.  This is a sometimes effective method for protecting employees from static pressure, but it also is great at producing a tremendous amount of noise and wasting a lot of compressed air every year. The noise produced by even a ¼ pipe with a cross drilled hole fed with 80 PSIG can easily exceed 90 dBA and consume up to 140 SCFM. The noise can be even louder, if there are burrs or rough edges from drilling out the pipe.  This is also a violation of OSHA standard 29 CFR – 1910.95 (a), if the employee is not using hearing protection.

Air Nozzle work

To meet this OSHA standard, EXAIR’s solution is to engineer features which cannot be dead-ended into a wide variety of compressed air products. We do this a variety of ways depending on the product.  For the Super Air Nozzles, we utilize multiple small orifices which are protected by raised fins.  The multiple orifices offer an escape path for the air in case a single orifice is plugged. The fins protect the orifices so that no one person can block more than one orifice at a time.

So if you are worried about an OSHA inspector knocking on your door, or maybe you aren’t sure if you should be worried, contact us.  The Application Engineering team here will help you determine what engineered solution you need to keep those pesky fines away.

Dave Woerner
Application Engineer
Davewoerner@EXAIR.com
@EXAIR_DW

Air Nozzles Blowoff Guide Available For FREE

Are you looking for an engineered Air Nozzle to replace your existing unsafe open pipe? Maybe you are wanting to reduce the sound level in your facility or decrease your energy costs? EXAIR offers a large variety of Air Nozzles that are ALL OSHA compliant to meet or exceed OSHA Standard 1910.242(b), by eliminating any potential for dead-ending the air flow out of the nozzle and keeping the outlet pressure safe. The design of our Super Air Nozzles ejects the compressed  air behind a series of fins so there is always path for the air to escape, meaning they cannot be dead ended.

OSHA Noise Level

ALL of EXAIR’s Air Nozzles meet or exceed noise exposure levels.

In addition, our air nozzles meet the OSHA Standard 29 CFR – 1910.95(a) for allowable noise exposure levels. Excessive noise in the workplace can cause stress, lack of concentration leading to accidents and potential long term hearing loss (More OSHA Noise Induced Hearing Loss info here). EXAIR’s air nozzles entrain surrounding ambient air up to 25 times for every 1 part of compressed air, producing much less wind shear, reducing the output sound level, while also making our units more efficient, consuming less compressed air.

 

air nozzle flow

How our Super Air Nozzles entrain surrounding air.

We offer nozzles from our smallest offering with a tiny M4 thread up to our largest 1-1/4 NPT unit, with varying force from 2 ounces up to 23 lbs., in zinc aluminum, stainless steel, brass or PEEK plastic.

With such a vast offering, we understand selection can seem difficult. To simplify the process we offer our Air Nozzles Blowoff Guide. Our FREE Blowoff Guide has all the information available in regards to force, dimensions, air flow patterns, air consumption and materials.You will also find detailed information about our full product line of Safety Air Guns as well.

blowoff guide

Order our complimentary Blowoff Guide today!

To order our complimentary blowoff guide, please click here. If you need additional information, please give us a call at 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

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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