Category: Safety

Decibels and How to Calculate

Published on by Al WooffittLeave a comment

Most of us are familiar with the term decibels. We know that it is a measure of sound, and that a larger decibel value means a larger sound. But the details of how they are calculated, or how different values compare to one another are not as widely known.

The first thing to note about sound levels is that they are not measured on a linear scale. Rather, they are measured on a logarithmic scale. This means that decibel values are not as intuitive as maybe we would like. A sound of 20dB is actually 10 times more powerful than a sound of 10dB, and 30dB would be 100 times more powerful than 10dB. If the scale was linear, 20dB and 30dB would be 2 and 3 times more powerful than 10dB (like with mass, for example, 20kg is twice as much mass as 10kg).

You can see why this is the case with the formula for calculating sound levels, which is as follows:

Image courtesy of OSHA Technical Manual (OTM)
Section III: Chapter 5 Appendix B5

It is important to note that the sound pressure levels calculated with this formula are unweighted. When we want to know how loud something will sound to us, we need to take into account how the human ear perceives different frequencies. The basic effect of this is that low and very high frequencies are given less weight than on the standard decibel scale, but the exact weighting can be seen in the chart to the left. This weighted measurement is denoted as dBA or sometimes dB(A) as opposed to the standard dB for sound pressure levels. Some common sounds and their dBA level can be seen on the chart below:

Due to this logarithmic scale, adding two sounds together can also be quite counter-intuitive as well. Our Model 1100 Super Air Nozzle will produce a sound level of 74 dBA, but two side by side will produce a sound of 78dBA. The specifics of this calculation are explained in this blog here, but OHSA provides a quick and easy way to calculate, as shown in the table below:

Difference Between Two Levels to Be AddedAmount to Add to Higher Level to Find the Sum
0-1 dB3 dB
2-4 dB2 dB
5-9 dB1 dB
10 dB0 dB
From <https://www.osha.gov/otm/section-3-health-hazards/chapter-5>

Now that you know how to calculate sound levels, it is important to understand the dangers inherent in prolonged exposure to high levels of noise. OSHA Standard 29 CFR-1910.95 (a) shows the Maximum Allowable Noise Exposure:

If you would like to find out if you need to address the sound level in your facility, you first need to take a baseline reading of your various processes and devices that are causing the noise. EXAIR’s Sound Level Meter, Model 9104, can help you out. It is an easy-to-use instrument that provides a digital readout of the sound level (so you don’t have to mess with logarithms!) They come with a NIST traceable calibration certificate and will allow you to determine what processes and areas are causing the most trouble.

If you would like to discuss sound levels in your facility, or any of your other compressed air needs, give us a call!

Al Wooffitt
Application Engineer

Send me an Email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_AW

Photo of Ear auricle Listen by geralt.  Pixabay License

Sound Power vs Sound Pressure vs Sound Pressure Level

Published on by Russ BowmanLeave a comment

A long time ago, in this galaxy right here, a movie called “Star Wars” was released. It was 1977, and, as a 10-year-old boy, the previews (that’s what we called “trailers” back then) grabbed my complete attention. I was fascinated by sound effects like the evil roar of the Empire’s TIE fighters, the sleek whistling hum of the Rebel’s X Wings, the terrifying explosion of Alderaan, and the victorious one of the Death Star. Imagine my surprise when, later that year, in 6th grade science class, we learned that SOUND DOESN’T TRAVEL IN A VACUUM!

Turns out, though, that sound DOES travel quite well through air. You’re almost certainly experiencing some right now – it’s actually quite difficult to eliminate ALL the sounds from any given area. Like anything that travels, it’s got a start and an end point, and we can measure parameters at both to quantify levels of sound power (at the starting point) and sound pressure (at the end point.)

Power is defined as the amount of energy transferred or converted per unit time, and applies to any form of energy…sound included. Philosopher types can debate the question “If a tree falls in the forest and nobody’s there to hear it, does it make a sound?” all day long, but engineers know the answer is “Of course it does!” Whether the sound comes from a hammer hitting a nail, a stereo’s speakers, a tree falling in a deserted forest or whatever, we can quantify the power generated in watts, just like any other generation of power.

Pressure is defined as the amount of force applied to a specified area. When we hear a sound, it’s because a sound wave created by the energy transfer at the source – perhaps by a tree hitting the ground in a forest – causes changes in the relatively low pressure being applied to our eardrums by the low power of the sound being generated in the quiet forest. This is measured in pascals – the SI unit of measure for pressure.

These units of sound power & sound pressure are used all the time by professionals who are calculating acoustic levels. For example, they’ll be used to determine how powerful a PA system has to be in a room of a certain size to hear a lecturer, or a singer, or a symphony. Each of those setups will need different sound power generation values for listeners to get the desired effect of what they’re hearing.

For those of us who are keen on preventing hearing loss, we’re going to concern ourselves with the sound pressure level. This is a logarithmic measure of the ratio of the sound pressure being applied to a reference, or base level, sound pressure. Most of the time, that reference level is the hearing threshold of a typical person without any hearing impairments, and it’s measured in decibels…a unit that most of us are at least somewhat familiar with. There are two ways to determine the sound pressure level: you can do the math, or you can use a measurement device, like EXAIR’s Model 9104 Digital Sound Level Meter.

Identify -and quantify – high noise levels quickly & easily with EXAIR Model 9104 Digital Sound Level Meter.

Compressed air use is LOUD. EXAIR has solutions for that, though. If you’d like to find out more, give me a call.

Russ Bowman, CCASS

Application Engineer
Visit us on the Web
Follow me on Twitter
Like us on Facebook

Air Nozzles and Jets Stay Set Hoses

Published on by Al WooffittLeave a comment

Very few applications are exactly alike. In fact, many applications have very specific needs; only a certain material will work, or a specific amount of force is needed, or the air flow needs to be directed at just the right location. You will have a hard time finding more flexibility and customization than with our Air Nozzles and Jets when combined with our Stay Set Hoses.

 EXAIR’s Air Nozzles come in a variety of materials, including Zinc-Aluminum, Stainless Steel Type 303 and 316, Brass, and PEEK (plastic). Each of the materials will cater to different situations – PEEK is non-marring for working with sensitive products. Stainless steel can withstand high temperatures when that is a concern.
In addition to multiple materials, EXAIR’s Air Nozzles can also produce a wide range of forces from 2oz all the way up to 23lbs. Whether you need a precise blowoff, or a forceful blast, we have you covered. With all of these variations, we have over 70 different nozzles to choose from!


Even with all of these options, there is one thing all of EXAIR’s Air Nozzles and Jets have in common. They are all designed to be compliant with OSHA 1910.242(b), which states “the use of compressed air for cleaning purposes at pressures at or greater than 30 psi is permissible if the outlet or source is fitted with a relief device that drops the pressure to less than 30 psi if the flow is dead-ended”. Our design achieves this by preventing the openings from being blocked off. This also has the added benefit of helping entrain the ambient air, making them very efficient in their compressed air usage.

Once you add in our Stay Set Hoses, the customization increases exponentially. Our Stay Set Hoses have a memory function, so they won’t creep or droop until you physically move them. They are perfect for directing the air flow in a particular direction, or at a specific target. The Stay Set Hoses come in lengths from 6” (15cm) to 36” (91cm), and they have threaded connections with either 1/4” NPT male on both ends or with a 1/8” NPT female X 1/4” NPT male thread.  The hoses are made from reinforced synthetic rubber and have a maximum pressure rating of 250 PSIG.

Flexible and durable, EXAIR Stay Set Hoses come in lengths from 6″ to 36″.

Whatever the specifics of your application are, we are sure to have a great solution. If you would like to discuss options for your application, feel free to contact me.

Al Wooffitt
Application Engineer

Send me an Email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_AW

How Does EXAIR Fit Into the NIOSH Hierarchy of Controls?

Published on by Tyler DanielLeave a comment

The Occupational Health and Safety Act of 1970 established the National Institute for Occupational Safety and Health, also known as NIOSH. This organization was founded with the goal of researching worker safety and health, and providing guidelines for employers to create safe and healthy workplace environments. A division of the Centers for Disease Control and Prevention (CDC), NIOSH has been diligently working to ensure that information is accessible to those who want to improve the safety of their operations.

On the NIOSH section of the CDC website, they’ve published a helpful guide for helping you to control and minimize the risk of exposure to hazards in the workplace. This hierarchy of controls provides a framework from most to least effective in terms of the way you manage these hazards and the exposure to your operators. This hierarchy of controls contains (5) levels of actions that can be taken to reduce or remove hazards from the workplace. In order of most to least effective, these controls are:

  1. Elimination
  2. Substitution
  3. Engineering Controls
  4. Administrative Controls
  5. Personal Protective Equipment (PPE)

 The least effective option for mitigating risks may not have been what you originally thought. PPE, or personal protective equipment, is something I’m sure you talk about often with your operators. Would you believe that this is ranked as the least effective method of preventing risks? This is because equipment can become easily damaged, may be uncomfortable and not always used when necessary, or simply used in an improper manner. We’ve all been guilty of doing something that we know we should’ve likely worn some PPE for, just out of convenience. Since it’s so easy to forget or simply not use, it makes PPE the least effective method when it comes to enhancing safety.

Moving up one notch on the scale we have administrative controls. These are also at the lower end of the effectiveness spectrum. These types of controls are centered around making changes to the way personnel works around the equipment. This can be achieved through implementation of training to correct operating procedures, cleanliness of the workplace, personal hygiene practices (proper hand-washing after handling hazardous materials for example). These, again, rely on the operator to listen and act in the way they’re trained.

Engineering controls reside in the middle of the effectiveness range. These are implemented by design changes to the equipment or process that reduces the risk of hazard. These controls can be very effective in protecting people regardless of the actions or behaviors of the operators. They are higher in cost generally than an administrative or PPE control, but can make operating costs lower and allow for a cost savings over the long-term.

Substitution is where EXAIR’s Intelligent Compressed Air Products come into play. By offering engineered solutions that meet or exceed OSHA Standards 29 CFR 1910.242(b) and 29 CFR 1910.95(a), EXAIR’s line of Safety Air Guns, Air Nozzles, and other engineered blowoffs will ensure your operators are not at risk when using our equipment. Anywhere you’re performing some sort of compressed air blowoff process, it’s important to be using equipment designed with safety in mind.

The most effective, but usually the hardest to implement, is elimination. This involves physically removing the hazard from the process. In many cases, a complete elimination is not going to be possible. That’s when you turn to the substitution method and look to EXAIR for a solution.

With years of industry experience under our belt, we’re well-equipped to help you improve safety in your workplace through a variety of off-the-shelf products. Give us a call today and we’ll be happy to discuss how we fit into your facility’s processes!

Tyler Daniel, CCASS

Application Engineer

E-mail: TylerDaniel@EXAIR.com

Twitter: @EXAIR_TD

Hierarchy of Controls Image:  used from  Public Domain