Tag: noise level

Reducing Pneumatic Exhaust Noise with EXAIR Mufflers

Published on by Jordan T ShouseLeave a comment

In many manufacturing facilities, compressed air systems are one of the largest contributors to workplace noise. Pneumatic cylinders, valves, vacuum generators, and cooling devices all exhaust compressed air, often creating sound levels high enough to require hearing protection. OSHA Standard 29 CFR 1910.95 outlines permissible workplace noise exposure levels, making noise reduction an important part of maintaining a safer and more comfortable work environment.

To help solve these issues, EXAIR offers several different styles of Silencing Mufflers designed for specific applications. Choosing the correct muffler can improve operator safety, reduce exhaust noise, and even help eliminate oil mist from compressed air systems.

Reclassifying Mufflers – Maximum Noise Reduction and Oil Removal

Reclassifying Mufflers are EXAIR’s most advanced muffler option. These mufflers are designed not only to reduce noise, but also to remove oil mist from exhausted compressed air. In pneumatic systems where lubricated air is used, exhausted oil mist can create slippery surfaces, contaminate products, and affect air quality.

EXAIR Reclassifying Mufflers can reduce sound levels by up to 35 dB while separating oil from the exhaust stream through a removable filter element. The collected oil drains into an integrated reservoir, helping facilities maintain cleaner and safer operations.

These mufflers are ideal for:

  • Pneumatic cylinders
  • Air valves
  • Lubricated compressed air systems
  • Applications where oil mist must be controlled

Sintered Bronze Mufflers – Simple and Cost Effective

Sintered Bronze Mufflers are a popular low-cost solution for reducing exhaust noise from pneumatic equipment. Their porous bronze construction allows compressed air to pass through with minimal back pressure, helping maintain proper equipment performance.

These mufflers are:

  • Easy to install
  • Available in a wide range of sizes
  • Ideal for standard cylinder and valve exhausts
  • Designed for minimal airflow restriction

Unlike Reclassifying Mufflers, Sintered Bronze Mufflers do not remove oil mist from the exhaust air. However, they remain an excellent option when a simple and economical noise reduction solution is needed.

Straight-Through Mufflers – Ideal for Remote Exhaust Applications

Straight-Through Mufflers are designed for applications where exhaust air needs to be piped away from operators or sensitive areas. These mufflers feature a corrosion-resistant aluminum shell lined with sound-absorbing foam and can reduce noise levels by up to 20 dB.

Their threaded inlet and outlet design makes them especially useful for:

  • Vortex Tubes
  • E-Vac Vacuum Generators
  • Cabinet Cooler Systems
  • Remote exhaust routing

Because the airflow passes directly through the muffler body, Straight-Through Mufflers are also less susceptible to clogging in certain applications.

Selecting the Right Muffler

Each EXAIR muffler style is designed to solve a different challenge:

Muffler TypePrimary BenefitTypical Use
Reclassifying MufflersBest noise reduction and oil removalPneumatic cylinders and lubricated systems
Sintered Bronze MufflersLow cost and easy installationGeneral pneumatic exhaust applications
Straight-Through MufflersRemote exhaust routing and lower clogging riskVacuum generators, vortex tubes, cabinet coolers

Reducing compressed air exhaust noise is often a simple upgrade that can have a major impact on workplace safety and operator comfort. Whether the goal is maximum sound reduction, oil mist filtration, or economical silencing, EXAIR offers a muffler solution designed for the application.

Jordan Shouse
Application Engineer
E: JordanShouse@exair.com
O: (513) 671‑3322
F: (513) 671‑3363
A: 11510 Goldcoast Dr Cincinnati OH 45249
www.exair.com

Find time on my calendar by scheduling a meeting here.

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

Reducing the Noise with EXAIR Mufflers

Published on by John BallLeave a comment
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.

Many manufacturing plants have a strong focus on safety for their workers.  One major safety concern that is overlooked is noise.   The Occupational Safety and Health Administration has a directive, 29 CFR 1910.95a, that defines noise exposure levels over time.  For an eight-hour day, the maximum noise level is 90 dBA.  Hearing loss is irreversible, but it can be prevented.  The CDC, Center for Disease Control, and NIOSH, National Institute for Occupational Safety and Health, report that “approximately 18% of all manufacturing workers have hearing difficulty”1. 

EXAIR manufactures intelligent compressed air® products to reduce noise levels in the work environment with our Super Air Nozzles, Super Air Knives, and Safety Air Guns for blow-off applications.  But there is another culprit that can be heard; discharge exhaust.  In this blog, I will cover the different types of mufflers that we offer to help reduce these sound levels.

Reclassifying Mufflers are designed to have two functions. They can cut noise levels by 35 dB and remove oil mist from the exhaust air.  Cylinders and valves that exhaust pressurized air may have oil in the line to keep the seals from sticking.  When exhausted, it can create a fine mist, which is dangerous for operators.  Reclassifying mufflers can reduce loud noise while also collecting any contaminants in the exhaust air.

Sintered Bronze Mufflers are simple in design, cost-effective, and easy to install. They have minimal back pressure to not restrict the operations of the pneumatic device.  They come in sizes from #10-32 thread to 1-1/2” NPT.  For a quick and simple way to reduce noise, the Sintered Bronze Mufflers are in stock for fast delivery.

Straight-Through Mufflers offer a way to reduce noise levels without worrying about clogging. They have an aluminum shell lined with sound-absorbing foam, and they can reduce the noise level by 20 dB.  EXAIR offers them with ports of ¼” NPT, 3/8” NPT, and ¾” NPT.  One side has a female thread, while the opposite side will have a male thread.  This can allow you to connect other items like hose kits to reduce noise.

In harsh environments, Heavy Duty Mufflers are used.  They have an outer aluminum shell with an internal stainless-steel screen.  They protect components like valves and cylinders from contamination entering the part.  And, the Heavy Duty Muffler can keep contaminants like rust from being ejected at high speed into the work area. They have a typical noise reduction of 14 dB.

Here is a test for you.  If you go and stand in your plant, you can probably hear loud noises coming from your pneumatic system.  EXAIR has engineered products to solve most of them.  In the Hierarchy of Controls from NIOSH, Personal Protection Equipment, or PPE, is the least effective.  A better control from this chart would be to isolate your operators from the hazard with an engineered product.  EXAIR can offer these solutions for many of your blow-off and pneumatic discharge applications.  If you wish to discuss in further details about the safety improvements that EXAIR can provide, you can contact an Application Engineer.  We will be happy to help. 

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

Note 1: https://www.cdc.gov/niosh/topics/ohl/manufacturing.html

The Trick To Adding Sound Levels Of Multiple Sources

Published on by Russ BowmanLeave a comment

If I put a 10 pound weight on a scale, the scale will read 10 pounds. If I put another 10 pound weight next to it, the scale with now read 20 pounds.

If I have $10 bill in my pocket…well, that’s a LOT more cash than I usually carry. But if I somehow come into possession of another $10 bill and put it in my pocket, now I have $20. And it probably won’t be for long.

If there’s an EXAIR Model 1100 Super Air Nozzle supplied with compressed air at 80psig, and my Sound Level Meter is reading a level of 74 dBA, and I hook another one up right next to it, my Sound Level Meter now reads about 78 dBA.

Wait, what? Did we just break math there? You, and your ears, will be happy to know that there’s perfectly valid math behind the third (as well as the first two) statements above. The third one’s just a little different, that’s all.

See, sound power (that’s “how loud” sound is, as measured at the point of generation) and sound pressure (“how loud” it is, as measured at the point where it’s heard) are both quantified in units called decibels. And, unlike mass or wealth (the first two examples above), which are linear & additive, measurement of sound power & pressure is done on a logarithmic scale. That means simple arithmetic won’t work…we have to use a logarithmic equation to ‘add’ those sound levels together. It looks like this:

Combined Sound Level (dBA) = 10 x log10[10SL1/10 + 10SL2/10 + 10SL3/10 …]

Where “SL1”, “SL2”, “SL3”, etc., are the sound levels, in decibels, for the “noisemakers” in question. So, for the two Model 1100 Super Air Nozzles, generating 74 dBA each:

10 x log10[1074/10 + 1074/10] = 77.65 dBA

And just to prove the math works, we made a video of a real live test:

All EXAIR Intelligent Compressed Air Products are engineered & manufactured to be safe, efficient, and as quiet as possible. If you’d like to find out more, give me a call.

Russ Bowman, CCASS

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