Tag: reduce noise

What is Sound and Interesting Facts About Sound

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In physics, sound is a wave of pressure. It occurs in a medium, which can be a solid, liquid or gas. Sound cannot travel through a vacuum, such as in space. The wave of pressure reaches our ears and causes the ear drum to vibrate, which then goes through a complex process to ultimately be perceived as audible sound.

There are several characteristics of sound waves that can be measured and help define the sound. A sound wave can be visualized as a repeating sinusoidal wave (see below), and can be described by these properties – frequency and wavelength, amplitude, and speed.

Sound Wave
Sound Wave
  • Frequency is the number of cycles in 1 second, and is measured in Hertz (Hz)
  • Wavelength is the distance over which 1 cycle occurs, and for audible sound is  between 17 m and 17 mm long
  • Amplitude is the measure of its change over a single period, and normally a measure of sound loudness
  • Speed is the distance traveled per unit time

The speed of sound in air can be found using the equation:  a = Sqrt (γ•R•T)

where for air:
γ = ratio of specific heats = 1.4,
R = gas constant = 286 m²/s²/K
T = absolute temperature in °K (273.15 + °C)

At room temperature, 22°C (71.6°F), the speed of sound is 343.8 m/s (760 mph)

Some interesting facts about sound:

  • Sounds generally travels faster in solids and liquids than in gases.
  • You can estimate the distance from a lightning strike by counting the seconds that pass between seeing the lightning flash and hearing the thunder.  Take this duration an divide by 5 to get the distance away, in miles.
  • Humans normally hear sound frequencies between 20 Hz and 20,000 Hz.
  • Sound waves above 20,000 Hz are known as ultrasound, and sound waves below 20 Hz are known as infrasound.
  • Sound travel through water close to 4 times faster then through air.
  • The sound of a cracking whip occurs because the speed of the tip has exceeded the speed of sound.

Sound that is too loud can be a problem. The Occupational Safety and Health Administration (OSHA) has set limits on the noise exposure that an employee can be subjected. Exceeding these values can cause permanent damage to your ears and cause noise induced hearing loss. So, knowing and reducing the sound levels within a manufacturing operation is important.

OSHA Chart

EXAIR has many products that can help reduce the sound levels in your processes.  With products such Air Knives, Air Wipes, Air Amplifiers, Air Nozzles and Jets, and Safety Air Guns, strong, quiet and efficient blowoff, drying, and cooling can be performed.

Quiet Products

If you have questions about sound and keeping your sound levels in check or 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.

Brian Bergmann
Application Engineer
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“Go Green” in 2019 With EXAIR’s Super Air Nozzles & Jets!

Published on by Tyler DanielLeave a comment

If one of your New Year’s resolutions for 2019 is to help improve your impact on the environment, look no further than EXAIR’s Engineered Air Nozzles & Jets. By upgrading your blowoff, cooling, and drying operations to use one of our Super Air Nozzles or Jets you can save as much as 80% of your compressed air usage when compared with an inefficient solution.

open tubes
Example of a manifold of open pipes

An open copper pipe or tube, even if “flattened” as we’ll commonly see, wastes an excessive amount of compressed air. This wasted compressed air can create problems in the facility due to unnecessarily high energy costs and the pressure drop that can be experienced affecting other processes. In addition to simply using too much compressed air, an open pipe or tube will often produce sound levels in excess of 100 dBA. At these sound levels, according to OSHA, permanent hearing damage will occur in just 2 hours of exposure.

OSHA Chart

By simply replacing the open tubes and pipe with an EXAIR Super Air Nozzle, you can quickly reduce air consumption AND reduce the sound level. Sound level isn’t the only thing an OSHA inspector is going to be concerned about regarding an open pipe blowoff, in addition OSHA 1910.242(b) states that a compressed air nozzle used for blowoff or cleaning purposes cannot be dead-ended when using with pressures in excess of 30 psig. I don’t know if you’ve ever tried to use an air gun with 30 psig fed to it, but the effectiveness of it is dramatically reduced. This is why there needs to be a device installed that’ll prevent it from being dead-ended so that you can operate at a higher pressure.

nozzle_anim_twit800x320
EXAIR Super Air Nozzle entrainment

EXAIR’s Super Air Nozzles are designed with fins that serve two purposes. They help to entrain ambient air from the environment, allowing us to maximize the force and flow from the nozzle but keeping the compressed air consumption minimal. In addition, these fins are what prevents the nozzle openings from being completely blocked off. Using an OSHA compliant compressed air nozzle for all points where a blowoff operation is being performed should be a priority. Each individual infraction will result in a fine if you’re subject to an OSHA inspection. Inspections are typically unannounced, so it’s important to take a look around your shop and make sure you’re using approved products.

sag-osha-compliant
The fins along the outside of the Super Air Nozzle prevent it from being dead-ended

So, go ahead and make 2019 the year of energy savings, increased efficiency, and improving worker safety. You’ll find all of the tools you need in EXAIR’s 32nd edition of the catalog. Click here if you’d like a hard copy sent directly to you! Or, get in touch with us today to find out how you can get saving with an Intelligent Compressed Air Product.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

 

OSHA 29 CFR 1910.15(a) – Occupational Noise Exposure Limits

Published on by Tyler DanielLeave a comment

Hearing loss due to high noise levels is a common problem in many industrial facilities. Without the use of proper PPE, hearing loss can occur quickly. This is a serious concern as hearing loss is permanent and once the damage is done there’s no way to reverse it. Due to this risk, OSHA strictly enforces standard 29 CFR-1910.95(a).

This directive discusses 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.

OSHA Chart

Hearing loss can occur in as little as 30 minutes when exposed to sound levels 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 protection hefty fines will be soon to follow. 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.

SoundMeter_new_nist225
Model 9104 Digital 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!

sound-level-comparison
Drilled pipes and open ended tubes are the common culprit for excessive noise levels. Replacing them with an engineered solution often eliminates the need for hearing protection.

If there’s 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!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

Safety, Efficiency, and Production Improvements

Published on by Dave WoernerLeave a comment

Last week, I received an email from a satisfied customer, after he had already purchased our product.  Come to find out this customer had not spoken to an application engineer during the planning stage to make their purchase. With our excellent resources listed at EXAIR.com, the customer was able to fulfill his application without even speaking to us. After his initial email of thanks, he also shared with me some details of his application that I want to share with you today.

The customer works as a machinist at a large aircraft part manufacturer. The parts require a very tight tolerance. A sample of each part needed to be gauged and measured in an automatic thread gauging machine or a coordinate-measuring machine (CMM). Their machining process required a water based flood coolant, so each part would be coated in water based coolant and chips, which needed to be remove before gauging. Before visiting EXAIR’s site, the company used a variety of homemade and commercial blow offs, as safety air gun tips. Here is a photo of (20) of the (25) nozzles the customer was using.

Aircraft manufacturer's obsolete nozzles

As you can see, the nozzles vary in design purpose, flow and safety. Most of the nozzles feature a cross drilled hole or a secondary escape path, but not all of the nozzles do. Any nozzle without a secondary relief port violates OSHA standard CFR 1910.242(b), so replacing some of the nozzles increased the safety in the plant. Secondly, these nozzles are wasteful in their use of compressed air because some were designed as liquid nozzles and have large exit holes. A hole that is 1/8″ in diameter at the nozzle outlet can consume up to 21.4 SCFM of compressed air at 80 PSIG. For comparison, the model 1103 Mini Super Air Nozzle with a 1/8″ NPT inlet will flow 10 SCFM at 80 PSIG, which would be a 53% compressed air savings. In 24 running hours, the 1103 nozzle will save 16,416 Standard Cubic Feet, which the plant spent $4.10 for a standard industrial compressor to produce (The standard for compressed air cost is $0.25 per 1,000 SCF). Replacing just one 1/8″ drilled hole with 1103 Mini Super Air Nozzle saves the aircraft company $1,026 over 250 working days running 24 hours a day.

Neither of these were the real reason that the customer emailed to thank us though. He was actually an office employee just entering the work force.  Starting in June until after the company finally acquiesced to his request to buy a better, quieter nozzle near the end of July, he had left work needing an aspirin to relieve the headache he acquired due to the noise from these other nozzles. The nozzles the machining center had been using would create noise levels between 88-100 dBA at 80 PSIG of inlet pressure. For reference OSHA mandates that employees are required to wear hearing protection, if they are exposed to noise levels over 90 dBA over an 8 hour work day.  The employees doing the machining wear hearing protection, but the employees in the office were still exposed and affected by the noise level.  This is just one anecdotal example, but everyday more and more research shows that noise exposure has a negative effect on our health and productivity in the workplace.  If you are interested in more information here are some links to a number of studies/research – please read this, here or this.

Anyway, that’s enough of my soapbox. The company purchased 25 of EXAIR’s 1103 Mini Super Air Nozzles and utilizing the same guns they were currently using saw between a 10-15 dBA decrease in noise levels near the work stations. Here is a photo of one of their setups with the model 1103 installed on one of their current air guns.

Nozzle Replacement
The 1103 Super Air Nozzle is an engineered solution to replace a plethora of commercial nozzles. It was a simple and cost effective retrofit which increased the comfort of employees.

 

We know that every time they squeeze that air gun trigger they will be using less compressed air than before, and we know they are now in compliance with OSHA. But the best benefit for EXAIR is we know that the engineer took the time to email us to thank us for taking away his headache everyday.  That’s enough for me.

Dave Woerner
Application Engineer
DaveWoerner@EXAIR.com
@EXAIR_DW