Tag: sound level

Measuring and Adding Sounds

Published on by John BallLeave a comment

My colleague, Russ Bowman, wrote a blog about “Sound Power vs Sound Pressure vs Sound Pressure Level”.  He discussed the logarithmic equations around sound.  I will be discussing what happens when you have more than one sound source, as often heard within manufacturing plants.  Sounds can be added together to determine the overall sound level that you hear.  This is very important when it comes to minimizing hearing loss.

In looking at a single source of sound, sound pressure is created by the loudness of a noise.  The units are measured in Pascals.  The lowest pressure perceived by human hearing is 0.00002 Pa, and we can use this value as a reference point.  From sound pressures, we can arrive at a sound pressure level which is measured in decibel, dB.  This correlation between sound pressures and sound pressure levels are calculated by Equation 1:

L = 20 * Log10 (P / Pref)

L – Sound Pressure Level, dB

P – Sound pressure, Pa

Pref – reference sound pressure, 0.00002 Pa

As an example, the sound pressure from a passenger car as heard from the roadside is 0.1 Pa.  With Equation 1, we can get the following decibel level:

L = 20 * Log10 (0.1Pa/0.00002Pa) = 74 dB

Because human ears are sensitive to different frequencies, the sound pressure levels can be modified, or weighted, to indicate an effective loudness level for humans.  This adjustment is done in two different ways; A-weighting and C-weighting.  The C-weighting is for very loud noises with high peaks or sharp impacts like gunfire. The A-weighting is the most used value as the sound pressure levels are adjusted by the frequency level.  For higher and lower frequencies, the change in the sound value is much greater than the mid-level frequencies that are within our hearing range.  Sound measurements for safety are measured on an A-weighted scale.  OSHA created a chart in the standard 29CFR-1910.95(a).  It shows the noise levels over exposure times for an operator.  To use the OSHA chart accurately, the total noise level in dBA should be calculated.

Hearing loss is the best known, but not the only, ill effect of harmful noise exposure. It can also cause physical and psychological stress, impair concentration, and contribute to workplace accidents or injuries.

To determine the total sound level, we can add all the sound pressure levels together by Equation 2:

Equation 2:

Where L1, L2… represents the sound pressure level in dBA for each sound source.

As an example, a manufacturing plant had an operator using a machine that had four copper tubes to blow off a cutting operation (reference photo below).

Blow off station

The decibel level for a copper tube was measured at 98 dBA.  The total amount of sound that the operator was exposed to was determined by Equation 2 with four values.

L = 10 * log10 (109.8 + 109.8 + 109.8 + 109.8)

L = 104 dBA

In looking at the OSHA chart above, the operator would only be allowed to operate the machine only a little over one hour without hearing protection.  In this same example, we replaced the copper tubes with an EXAIR Super Air Nozzle, model 1100SS.  The noise level for each nozzle is 74 dBA at 80 PSIG (5.5 bar).  By replacing all four copper tubes with Super Air Nozzles, Equation 2 becomes:

L = 10 * log10 (107.4 + 107.4+ 107.4 + 107.4)

L = 80 dBA

The total sound level is now in accordance with OSHA regulations for the operator to work all 8 hours at the machine without hearing protection.

A commonly used acronym for hearing safety is NIHL, or Noise Induced Hearing Loss.  To keep your operators safe and reduce NIHL, it is important to measure the total sound level in that area.  As a protocol in safety, it is a requirement to use engineering standards before purchasing personal protective equipment or PPE.  For the customer above, they followed that protocol with our Super Air Nozzles.  If you need to reduce noise levels in your facility, EXAIR offers a large line of blow-off products that can meet the safety requirements.  You can contact an Application Engineer for more information. 

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

Photo: Ear by PublicDomainPictures  Pixabay License

The Hierarchy of Controls and How It Applies to EXAIR Compressed Air Solutions

Published on by Jordan T ShouseLeave a comment

In industrial environments, safety teams rely on the Hierarchy of Controls to reduce workplace hazards. Rather than relying on personal protective equipment (PPE), this process prioritizes eliminating risks at their source or engineering them out of the process. For manufacturers, maintenance teams, and engineers, applying the hierarchy of controls can significantly improve safety, reduce downtime, and increase efficiency.

Many compressed air applications—blow off, cooling, conveying, and static elimination—present opportunities to implement safer and more effective solutions using products from EXAIR.

What Is the Hierarchy of Controls?

The Hierarchy of Controls is a widely accepted framework in occupational safety used to minimize or eliminate exposure to hazards. It is commonly promoted by organizations like the Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health.

The hierarchy ranks safety controls from most effective to least effective:

  1. Elimination – Remove the hazard entirely
  2. Substitution – Replace the hazard with a safer alternative
  3. Engineering Controls – Isolate people from the hazard
  4. Administrative Controls – Change the way people work
  5. Personal Protective Equipment (PPE) – Protect the worker with gear

While elimination and substitution are ideal, they are not always feasible in manufacturing environments.

Applying the Hierarchy of Controls to Compressed Air Systems

1. Elimination

The most effective control is removing the hazard entirely. In compressed air systems, this can mean eliminating unsafe blow-off methods like open pipes or drilled tubing that create excessive noise, dangerous dead-end pressure, and flying debris. Replacing these setups with engineered solutions from EXAIR Corporation removes many of these hazards while maintaining performance.

2. Substitution

Substitution replaces hazardous equipment or processes with safer alternatives. In many facilities, this involves switching from improvised blow-off devices to engineered products like air nozzles or air knives. These solutions reduce noise, improve airflow efficiency, and significantly lower compressed air consumption.

3. Engineering Controls

Engineering controls isolate workers from hazards through equipment design. Many EXAIR products function as engineering controls by improving safety and reliability in compressed air systems. Devices like safety air nozzles, cabinet coolers, and air knives help control airflow, reduce noise levels, and prevent unsafe pressure conditions.

EXAIR Electronic Flow Control

4. Administrative Controls

Administrative controls focus on improving procedures and training. This includes compressed air safety training, pressure guidelines, and routine system audits. While helpful, these controls rely on human behavior, so they are most effective when combined with engineered solutions.

5. Personal Protective Equipment (PPE)

PPE—such as safety glasses or hearing protection—is the last line of defense. It protects workers from hazards but does not remove the risk itself. Implementing engineered compressed air solutions can reduce many hazards before PPE becomes necessary.

Compressed air is one of the most widely used utilities in manufacturing—but it’s also one of the most misused. Improper blow off setups, excessive noise, and inefficient airflow can introduce safety hazards and energy waste.

With the right approach and the right equipment, companies can create safer, quieter, and more efficient processes—while maximizing the performance of their compressed air systems.

Solutions from EXAIR, help organizations move up the hierarchy by replacing unsafe methods with engineered products designed specifically for industrial environments.

Jordan Shouse, CCASS

Application Engineer / Sales Operations Engineer

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Hierarchy of Controls Image courdsey of CDC.Gov

Noise In The Workplace

Published on by Russ BowmanLeave a comment

The Center for Disease Control (CDC) estimates that 22 million workers are exposed to potentially dangerous levels of noise at work every year. That’s “only” about 15% of the total number of people who are employed in the United States, but if you’re one of them, you should absolutely know the risks, and how to protect yourself. Obviously, high noise levels can cause hearing loss, but do you know what else it causes?

  • Cardiovascular disease. Constant noise exposure causes stress, and stress triggers the release of hormones that increase your blood pressure, which can lead to ischemic heart disease, strokes, and arrhythmia.
  • Sleep disruption. Studies show chronic noise exposure during the day can cause difficulty falling asleep, shortened sleep cycles, and frequent wake-ups during the night. All this leads to chronic fatigue and a host of long-term health issues.
  • Immune system suppression. While the exact nature of the relationship is unclear, recent studies have indicated that noise can cause changes in our immune systems.
  • Cognitive impairment: Continued noise exposure causes memory impairment, attention deficits, and reduced concentration.
  • Mental health issues. Not only does continued noise exposure release hormones like cortisol & adrenaline (causing the chronic stress that’ll literally break your heart; see above), it directly influences anxiety, depression, and irritability.
Don’t let this happen to you.

So, how do we protect ourselves? If you said “ear plugs,” you’re not wrong…but did you know that hearing protection in the form of personnel protective equipment (PPE) is considered the LEAST effective method of mitigating noise exposure? The National Institute for Occupational Safety and Health (NIOSH, a sister agency of the Occupational Safety and Health Administration, or OSHA) developed a hierarchy of controls…a “good, better, best” framework, if you will, of methods to address workplace hazards:

Even though hearing protection (the PPE in this case) is least effective, the intent of the hierarchy graphic is not to dismiss it, but to categorize it as a last resort. If all else fails (or, more often, comes up short,) ear plugs are your – and your hearing’s – best friend.

If the source of the noise cannot be eliminated (and let’s face it, an awful lot of industrial processes are necessarily loud), the next best thing to do is to substitute a quieter method or device. That’s where EXAIR comes in: the design of our engineered Air Knives, Air Nozzles, and Air Amplifiers exploits certain principles of fluidics to mitigate the noise levels associated with the rapid depressurization of compressed air when it’s blown for cleaning, drying, cooling, etc. The key to this is entrainment:

EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier are engineered to entrain enormous amounts of air from the surrounding environment.

While this entrainment makes EXAIR products EXTREMELY efficient (the compressed air consumption ends up being a fraction of the total developed flow), it also creates a low velocity boundary layer around the primary high velocity & forceful airflow. This layer attenuates the sound level of that high velocity flow.

Compressed air use can be loud, wasteful, and dangerous, but it doesn’t have to be. If you’re looking for a quiet, safe, and efficient solution for your use of compressed air, give me a call.

Russ Bowman, CCASS

Application Engineer
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Sound Level of Cicadas

Published on by Jordan T ShouseLeave a comment

At the time of writing this blog, Cincinnati is experiencing our usual 17-year brood of cicadas. Millions, if not billions, of 17-year cicadas have emerged in Cincinnati and Southwest Ohio, making spending any amount of time outside unbearable. My four-year-old’s favorite part of the day is swinging on the back porch, and he even wants to go right back inside after just a few minutes.

I stuck the EXAIR 9104 Digital Sound Level Meter inside of one of our bushes here at the office. Within a 3′ radius, I counted 10–15 cicadas crawling around pretty casually. And they were producing a whopping 90 dBA! And if i shook a branch and really got them worked up, it peeked over 101 dBA.

Now while it takes repeated exposures of sufficient duration to cause hearing loss. And in a few weeks these cicadas will be gone; you probably don’t need to worry about the 2025 cicadas affecting your hearing. Noise exposure is, however, a real issue for most manufacturing facilities. Due to this risk, OSHA strictly enforces standard 29 CFR-1910.95(a).

This directive outlines the effects of noise and limits exposure based on the dBA. The table below indicates the maximum allowable exposure time to different noise levels. Sound levels that exceed these levels should first be addressed by proper engineering controls, such as isolating the source of the sound from personnel or replacing the cause of the sound with something like an engineered compressed air nozzle. When such controls aren’t feasible, proper PPE must be worn to protect the operator.

Hearing loss is the best known, but not the only, ill effect of harmful noise exposure. It can also cause physical and psychological stress, impair concentration, and contribute to workplace accidents or injuries.

Hearing loss can occur in as little as 30 minutes when exposed to sound levels of 110 dBA or greater. Operators have a tendency not to use PPE as directed. If an OSHA inspector comes to your facility and notices that the sound levels exceed the maximum allowable level without PPE protection being worn, hefty fines will soon be following. In this example from the United States Department of Labor, a company was fined a total of $143,000 for failing to protect their employees.

EXAIR 9104 Sound Level Meter

In order to identify the places or processes in your facility that are causing the problems, you’ll need a tool to measure the sound level. EXAIR’s easy-to-use Digital Sound Level Meter allows you to measure and monitor the sound level pressure in a wide variety of industrial environments. The source of the loud noise can then be identified and isolated so that corrective action can be taken. For compressed air-related noise, EXAIR manufactures a wide variety of engineered compressed air products that can reduce the sound level dramatically. In many cases, EXAIR products are capable of reducing noise levels by as much as 10 dBA. Since the dBA scale is logarithmic, this equates to cutting the sound level in half!

If there are processes within your facility that are above these limits, and you’d like to eliminate relying on proper PPE, give an Application Engineer a call. We’ll help walk you through the selection process and make sure that when the OSHA inspector comes knocking you’re prepared! Sorry, but we will not be able to help you with your Cicada problems. We just have to let nature do its thing, and they will be gone in a few weeks. Until 2027, that is, when we get hit with the 10-year brood!

Jordan Shouse, CCASS

Application Engineer

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