Tag: occupational health and safety

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

More And More Award Winning Products From EXAIR

Published on by Russ BowmanLeave a comment

As you might expect, a LOT of things have changed at EXAIR Corporation since 1983. Most of our current senior management had yet to graduate high school, and a fair number of current employees had yet to BE BORN. According to our computer system (another BIG change since 1983), our first ten customers were here in southwest Ohio (#11 was in Michigan), and now, we sell direct across the US & Canada, and our worldwide distributor network offers representation on six continents. One thing that hasn’t changed, though, is our founder’s vision of manufacturing quiet, safe, & efficient compressed air products for process improvement in just about any industry that uses compressed air. And THAT, dear reader, continues to gain high profile attention. The photo above shows the seven awards that our products have recently won, which were announced in 2021 or early 2022. Here’s a rundown:

Plant Engineering 2020 Product of the Year (Fluid Handling) GOLD AWARD:
1/2 NPT No Drip External Mix Air Atomizing Spray Nozzles

No Drip External Mix Atomizing Spray Nozzles

The 1/2 NPT models are the latest addition to our newest product line. The External Mix version offers the highest liquid flow rate, and largest pattern coverage. Among the applications where they’ve excelled so far are:

  • Snack food provider – applying flavoring to bulk snack materials.
  • Commercial bakery – spraying cooking oil onto pans used in a conveyor oven.
  • Sporting goods manufacturer – applying adhesive to the tops of skateboard decks to glue the grip tape on.

Plant Engineering 2020 Product of the Year (Material Handling Systems) GOLD AWARD:
2-1/2 NPT 303SS Threaded Line Vac™

EXAIR's Threaded Line Vac Family
EXAIR Threaded Line Vac + Your Pipe + Compressed Air = Instant Conveyor System

For bulk material conveyance, it really doesn’t get any simpler than EXAIR Air Operated Conveyors. Stainless Steel models are especially popular when the environment – or the product – is corrosive, or hot…they’re good to 400F (204C), and can even be modified with High Temperature components for exposure up to 900F (482C). The Threaded versions have been successfully used to:

  • Recycle sprinkles applied to wafers into a return hopper in a candy production facility.
  • Replacing an auger conveyor to allow for homogenous mixing of grains & supplements in feed stock at an agricultural mill.
  • Providing a low cost solution to convey product into a hopper at a grain processing plant.

Plant Engineering 2020 Product of the Year (Maintenance Tools & Equipment) SILVER AWARD
Occupational Health & Safety 2021 New Product of the Year (Industrial Hygiene-Dust Control) WINNER
Occupational Health & Safety 2021 New Product of the Year (Health & Safety/Cleanup) PLATINUM
EasySwitch® Wet-Dry Vac

Like our Spray Nozzles product line, our Industrial Housekeeping Products line has also grown considerably over the years. The Deep Hole Vac-u-Gun and Heavy Duty HEPA Vac were real game changers when they came along, and the EasySwitch® Wet-Dry Vac Systems are likewise making an impact. Switching from wet to dry operation is, as advertised in the name itself, INCREDIBLY easy. Among our satisfied customers are:

Occupational Health & Safety 2021 New Product of the Year (Lab Safety) WINNER
Intellistat® Ion Air Gun™

The newest innovation in a long line of EXAIR static elimination solutions, the Model 8500 Intellistat® Ion Air Gun is made for laboratories, clean rooms, medical & electronic applications, and carries an ISO 14644-1 Class 5 rating for clean room use. Because of their rapid decay rates and lightweight construction, they’re used in a diverse range of applications and areas, including:

  • A supplier of fiberoptic parts uses an Intellistat® to remove dust and static charge from product prior to packaging.
  • A medical device manufacturer has one in a Class 7 clean room for silicone parts cleanliness.
  • A nutritional supplements maker uses their Intellistat® to remove static charge & powder residue from the tops of plastic bags before sealing them. The excess/residual powder causes them not to seal correctly.

Machine Design 2021 Big Idea! (Electrical Components) BRONZE AWARD
Gen4® Static Eliminator Power Supply

All EXAIR Gen4 Static Eliminators use one of two Power Supplies – your choice of the 2-port Model 7960, or the 4-port Model 7961.

EXAIR Static Eliminators produce ionized air via a Corona discharge, which requires high voltage, low current electricity. The Gen4® Static Eliminator Products feature armored & shielded cables with an internal ground, for safety and reliability. The ground path is completed through the cable and the Power Supply port, eliminating the need for an external ground connection. Faults in external ground connections result in the majority of the problems with those devices, so the internal ground is a “Big Idea!” indeed. The Gen4® Static Eliminator Power Supplies are switchable for 115VAC or 230VAC voltages, and are offered in 2, or 4 outlet designs, which can power any 2, or 4 EXAIR Static Eliminator Products. Like most EXAIR Intelligent Compressed Air Products, they’re used for a wide range of applications, in a wide range of industries:

If you’d like to find out more about these, or any of our other engineered compressed air products (we’re pretty proud of them all), give me a call. I can talk about them all day long…and sometimes I do!

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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