Tag: engineering

EXAIR and the Hierarchy of Controls

Published on by Jordan T ShouseLeave a comment

The CDC (Center for Disease Control) published a useful guide called “Hierarchy of Controls” that details (5) different types of control methods for exposure to occupational hazards while showing the relative effectiveness of each method.

NIOSH_Hierarchy_of_Controls
Hierarchy of Controls

 

The least effective methods are Administrative Controls and Personal Protective Equipment (PPE). Administrative Controls involve making changes to the way people perform the work and promoting safe practices through training. The training could be related to correct operating procedures, keeping the workplace clean, emergency response to incidents, and personal hygiene practices, such as proper hand washing after handling hazardous materials. PPE is the least effective method because the equipment (ear plugs, gloves, respirators, etc.) can become damaged, may be uncomfortable and not used, or used incorrectly.

In the middle range of effectiveness is Engineering Controls. These controls are implemented by design changes to the equipment or process to reduce or eliminate the hazard. Good engineering controls can be very effective in protecting people regardless of the the actions and behaviors of the workers. While higher in initial cost than Administrative controls or PPE, typically operating costs are lower, and a cost saving may be realized in the long run.

The final two, Elimination and Substitution are the most effective but can be the most difficult to integrate into an existing process. If the process is still in the design phase, it may be easier and less expensive to eliminate or substitute the hazard. Elimination of the hazard would be the ultimate and most effective method, either by removing the hazard altogether, or changing the work process so the hazard is no longer part of the process.

EXAIR can help your company follow the Hierarchy of Controls, and eliminate, or substitute the hazards of compressed air use with relative ease. 

Home of Intelligent Compressed Air Products

Engineers can eliminate loud and unsafe pressure nozzles with designs that utilize quiet and intelligent compressed air products such as Air Nozzles, Air Knives and Air Amplifiers. Also, unsafe existing products such as air guns, can be substituted with EXAIR engineered solutions that meet the OSHA standards 29 CFR 1910.242(b) and 29 CFR 1910.95(a).

In summary, Elimination and Substitution are the most effective methods and should be used whenever possible to reduce or eliminate the hazard and keep people safe in the workplace. EXAIR products can be easily substituted for existing, unsafe compressed air products in many cases. And to avoid the hazard altogether, remember EXAIR when designing products  or processes which require compressed air use for cooling, cleaning, ejection, and more. 

If you have questions about the Hierarchy of Controls and safe compressed air usage from any of the 15 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Jordan Shouse
Application Engineer

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Hierarchy of Controls Image:  used from  Public Domain

The Bernoulli Principle

Published on by Brian FarnoLeave a comment

When catapults would hurl stones and projectiles at castles there weren’t thinking of how the stones flew or what could make them fly better, often they went with the “Tim Taylor method” of MORE POWER.  It wasn’t until thousands of years later that mathematicians started to talk about gases and liquids and how they react to different scenarios. Things like how does air react to a stone being launched through it. Johann Bernoulli played a significant role and calculated a lot of this out throughout his life and discovered what is now called the Bernoulli Principle.

Bernoulli discovered that when there is an increase in the speed of a fluid, a simultaneous decrease in fluid pressure occurs at the same time. This is what explains how a plane’s wing shape matters. It also can showcase how a curveball coming into the strike zone can fall out and cause an outlandish “STTTeeerriike Three” from the umpire. It is also sometimes confused with the Coandă effect. While both effects have a tremendous impact on our modern lives, the best way I have learned these effects is through videos such as the one below.

As mentioned within the video, there are numerous effects that can closely relate to the Bernoulli effect, the best example I see is the curveball which when implemented correctly can cause a very upset batter, while the pitcher has the game of his or her career.

If you would like to talk about some scientific discoveries that have you puzzled, or if you want to figure out how we can use one of these effects to help your application, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Video Source: Fizzics Organization – 10/8/2014 – retrieved from https://www.youtube.com/watch?v=-c_oCKm5FLU&list=PLLKB_7Zd6leNJmORn6HHcF78o2ucquf0U

Torque Values and Tapered Threads – Do They Go Together?

Published on by Brian FarnoLeave a comment

IMG_20200202_155004_377.jpg

Over the past few weeks, I have been working on various cars in the garage with some good friends. We generally get together and help each other out to make the jobs go easier as well as help each other learn more about keeping our family’s vehicles safe and even helping out some others that don’t have the means to work on their own vehicles. Throughout these repairs, we always end up in some type of discussion over something fairly technical. Sometimes it is the proper installation of a part such as take the bolts to snug, back them out, then torque to half the total torque value, back off again, then finally tighten to the complete torque.

We also share different ways of doing the jobs, such as how to lessen the amount of hot oil you are about to pour all over your hand, or how to get that rusted bolt out without a torch and without breaking it. One discussion that comes up quite frequently is torque specs and then the torque spec for a tapered thread.

In case you were not aware, the NPT or BSPT (male) inlets on EXAIR products are both a tapered thread. Tapered threads are generally used on pipe fittings under pressure to seal better and provide a secure engagement. When comparing this to a standard bolt, or straight thread, one is generally accustomed to receiving a torque spec on just how tight to get the fitting or threaded product. For example, the 1/4-20 bolts used in our Super Air Knives are torqued to 7.5 ft-lbs. in order to properly seal the cap, shim, and body together. These are straight threads and thus a torque spec is often driven by the material, size, and thread of the bolt. Torque on tapered threads such as NPT or BSPT fittings is not as easy to find, and not really reliable.

For tapered threads, the engagement of the thread is not always at the same point due to differing tolerances on thread dimensions. These differences create different points of thread engagement with the corresponding thread it is tightening into. For these scenarios, the torque specification is not always best suited as a numeric value. If you search hard enough you can find a table like the one shown below, but again, not the best value to use when installing a tapered thread.

Size in-lbs N-m
1/16″ 5 0.57
1/8″ 7 0.79
1/4″ 16 1.81
3/8″ 23 2.6
1/2″ 30 3.39
3/4″ 54 6.1
1″ 78 8.81

I personally would not use a straight numeric torque when tightening something with stainless steel thread into a brass fitting, or other dissimilar materials together. For this scenario, I would recommend using something like the table below. The TPFT value is, turns past finger tight. This means you would snug the super air nozzle, vortex tube, or other fittings by hand to finger tight. Then using a wrench or two if needed, turn the fitting to the correct number of revolutions for the given thread size. By utilizing this method and the correct amount of thread sealant, see John Ball’s video blog below, you can ensure there will not be a concern on whether or not the joint will leak and also if the fitting is tight enough.

NPT Size TPFT
1/8″ 2-3
1/4″ 2-3
3/8″ 2-3
1/2″ 2-3
3/4″ 2-3
1″ 1.5-2.5

If you would like to discuss torque settings, installation of your engineered compressed air solution, or even what might be wrong with your minivan, contact us.

Brian Farno
Application Engineer/Garage Mechanic Extraordinaire
BrianFarno@EXAIR.com
@EXAIR_BF

Sound: What Is It … More Importantly, Weighted Scales of Frequencies

Published on by Brian FarnoLeave a comment

We’ve blogged about sound and what exactly it is before, see the link. Understanding that sound is vibration traveling through the air which it is utilizing as an elastic medium.  Well, rather than me continue to write this out, I found a great video to share that is written in song to better recap how sound is created.

Now that we have that recap and understand better what sound is let’s dig a little deeper to better understand why some sounds may appear louder to a person when they may not appear different on a sound scale that is shown by something like a Digital Sound Level Meter.

Loudness is how a person perceives sound and this is correlated to the sound pressure of the frequency of the sound in question.  The loudness is broken into three different weighing scales that are internationally standardized. Each of these scales, A, C, and Z apply a weight to different frequency levels.

  1. The most commonly observed scale here in the USA is the A scale. A is the OSHA selected scale for industrial environments and discriminates against low frequencies greatly.
  2. Z is the zero weighting scale to keep all frequencies equal, this scale was introduced in 2003 as the international standard.
  3. C scale does not attenuate these lower frequencies as they are carrying the ability to cause vibrations within structures or buildings and carry their own set of risks.

To further the explanation on the A-weighted scale, the range of frequencies correlates to the common human hearing spectrum which is 20 Hz to 20kHz. This is the range of frequencies that are most harmful to a person’s hearing and thus were adopted by OSHA. The OSHA standard, 29 CFR 191.95(a), that corresponds to noise level exposure permissible can be read about here on our blog as well.

When using a handy tool such as the Digital Sound Level Meter to measure sound levels you will select whether to use the dBA or dBC scale.  This is the decibel reading according to the scale selected. Again, for here in the USA you would want to focus your measurements on the dBA scale. It is suggested to use this tool at a 3′ distance or at the known distance an operator’s ears would be from the noise generation point.

Many of EXAIR’s engineered compressed air products have the ability to decrease sound levels in your plant. If you would like to discuss how to best reduce sound levels being produced within your facility, please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

1 – Fun Science: Sound – @charlieissocoollike – https://youtu.be/xH8mT2IQz7Y