Sound: What Is It … More Importantly, Weighted Scales of Frequencies

We’ve blogged about sound and what exactly it is before, see the link. Understanding that sound is vibration traveling through the air which it is utilizing as an elastic medium.  Well, rather than me continue to write this out, I found a great video to share that is written in song to better recap how sound is created.

Now that we have that recap and understand better what sound is let’s dig a little deeper to better understand why some sounds may appear louder to a person when they may not appear different on a sound scale that is shown by something like a Digital Sound Level Meter.

Loudness is how a person perceives sound and this is correlated to the sound pressure of the frequency of the sound in question.  The loudness is broken into three different weighing scales that are internationally standardized. Each of these scales, A, C, and Z apply a weight to different frequency levels.

  1. The most commonly observed scale here in the USA is the A scale. A is the OSHA selected scale for industrial environments and discriminates against low frequencies greatly.
  2. Z is the zero weighting scale to keep all frequencies equal, this scale was introduced in 2003 as the international standard.
  3. C scale does not attenuate these lower frequencies as they are carrying the ability to cause vibrations within structures or buildings and carry their own set of risks.

To further the explanation on the A-weighted scale, the range of frequencies correlates to the common human hearing spectrum which is 20 Hz to 20kHz. This is the range of frequencies that are most harmful to a person’s hearing and thus were adopted by OSHA. The OSHA standard, 29 CFR 191.95(a), that corresponds to noise level exposure permissible can be read about here on our blog as well.

When using a handy tool such as the Digital Sound Level Meter to measure sound levels you will select whether to use the dBA or dBC scale.  This is the decibel reading according to the scale selected. Again, for here in the USA you would want to focus your measurements on the dBA scale. It is suggested to use this tool at a 3′ distance or at the known distance an operator’s ears would be from the noise generation point.

Many of EXAIR’s engineered compressed air products have the ability to decrease sound levels in your plant. If you would like to discuss how to best reduce sound levels being produced within your facility, please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

1 – Fun Science: Sound – @charlieissocoollike – https://youtu.be/xH8mT2IQz7Y

 

EXAIR Leads the Way with Product Standards

Standards seem to continually get introduced and updated. There is an ever increasing number of local, regional, federal, and even global standards to comply with.  We pay close attention to these standards and have the largest number of standards upon our products.

meets or exceeds oshaThe standards the every EXAIR product meets or exceeds are the OSHA standards for dead-end pressure as well as allowable noise level exposure.  The dead-end pressure directive is OSHA standard 29 CFR 1910.242 (b).  The standard refers to the fact that compressed air can be dangerous when the outlet pressure of a hole, hose or copper tube is higher than 30 psig (2 BAR).  In the event the opening is blocked by a hand or other body part, air may enter the bloodstream through the skin, resulting in a serious injury.  All of the compressed air products manufactured by EXAIR have been designed for safety.  All are safe to be supplied with higher pressure than 30 psig and still meet or exceed the OSHA standard.

The OSHA standard 29 CFR – 191.95 (a) refers to the maximum allowable noise exposure that an operator is permitted to be exposed to for a given period of time.   The chart of allowable exposure times is shown below.   All EXAIR products are engineered to create the minimum amount of noise while efficiently utilizing compressed air.   Many times blow offs are cross drilled to permit air to escape in order to meet the OSHA standard for dead end pressure, this process increases the noise level generated by that blow off considerably.

OSHA Noise Level

One of the most stringent compliance that EXAIR has upon its products is the UL/CUL listings and recognition.  All EXAIR Cabinet Cooler Systems are UL listed, we were the first to insure your electrical cabinet’s NEMA integrity remained by putting our Cabinet Cooler systems to the UL test. This means that the Underwriters Laboratories have deemed these products safe for operation throughout the US and Canada per their standards that are applicable for each of the product groups.   The products undergo numerous tests and scenarios to ensure that an operator will be safe during the normal operation of the units.   The tests for the Cabinet Cooler Systems includes environmental exposure for the given NEMA type of the enclosure along with many other tests.  The Static Eliminator Power Supplies are also UL listed.

cULlistedcULrecognized

CE is another standard which EXAIR pays great attention to to meet or exceed. CE is a standard that is normally preferred when dealing with countries outside of the US but is gaining popularity within the states as well.  CE being a European standard actually stands for a french phrase, “Confrmité Eurpéene” which is translated to “European Conformity”.  Any EXAIR product displaying the CE mark conforms where there are applicable directives.CE

The RoHS directive is targeted on heavy metals that are generally found within electronics.  Substances like Mercury, Lead, Polybrominated biphenyls, Cadmium, or Hexavalent chromium.  In order to meet the RoHs directive a product must have 100 parts per million or less of mercury and for other substances there must be less than 0.01% of the substance by weight in a raw homogeneous materials level. All EXAIR products which are electronic or contain electronic devices are compliant to the 2002/95/EC RoHS directive, also including the amendment outlined in the European Commission decision L 214/65.  This includes all EXAIR Static Eliminators, Electronic Flow Control, and Electronic Temperature Control products.ROHS_Vector

EXAIR maintains records to be sure our supply chain is providing product which meets the conflict mineral free guidelines of the Dodd-Frank Act.  EXAIR supports Section 1502 of the Dodd-Frank Wall Street Reform and Consumer Protection Act and we are committed to compliance with the conflict minerals rule in order to curb the illicit trade of tin, tantalum, tungsten and gold in the DRC region. EXAIR is using the CMRT 3.02 template to document our supply chain and commitment to conflict free products. When requested we will even provide the needed forms to support our customer’s efforts in complying with the Dodd-Frank Act.

conflictfree

REACH, is another European Community Regulation this time on chemicals and their safe use.  REACH is targeted to ensure personnel and environmental health by identifying the intrinsic properties of chemical substances easily.  REACH stands for Registration, Evaluation, Authorization and Restriction of Chemical substances and was written into law in 2007. EXAIR products are not required to be registered per Title II, Article 7, paragraph 1  of the legislation since they do not contain substances that are intentionally released.   This is to ensure compliance with Regulation (EC) No 1907/2006 Title I, Article 3, paragraph 3, the European Union requires registration of chemicals and substances imported into the EU to ensure a high level of protection of human health and environment.

Reach

 

To conclude, when there is a safety audit, safe sourcing directive or some other form of standard/conformance that you need to meet, consider EXAIR compressed air products. Please contact us to find out if we can help you meet or exceed those standards.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

Safety Air Gun Improves Aluminum Extruding Machining Process

I was doing some work around the house Saturday when I heard my wife shouting out from our laundry room….”Something is wrong with our dryer. This is the 3rd time I’ve restarted it and the clothes are still wet!”. Now having been in this situation before, I knew this meant that the exhaust was probably clogged with lint (again).

See, our laundry room runs parallel to our family room and the exhaust ducting goes up and then across the laundry room, across the family room and then exhausts on the side of the house. (I would like to find the person who thought this was a good idea!). I have thought about re-routing the ducting but the only other option would be to have the exhaust on the front of the house which will “never happen” (per my wife). So I usually end up taking my vacuum and attaching as many extensions as possible to reach as much of the ducting as I can. I have tried a few other methods with no success – like taking my leaf blower and, from the outside of the house, blow the lint back towards the laundry room and into a garbage can. (hint: make SURE your wife is not in the laundry room when attempting this…. They don’t react too well when they get covered in lint!)

This made me think of an application I worked on last week with an aluminum extrusion company. The customer cuts lengths of aluminum siding from 1’ up to 10’ in length and, standing at one end of the material, are using a standard blow gun to try and blow out the chips but are unsuccessful. They reviewed our website but were still unsure what product may fit their needs best, so they gave us a call.

We discussed their application and the customer was able to email pictures. After reviewing the pictures I recommended using one of our Soft Grip Safety Air Guns with our Model # HP1125, 2” Flat High Power Super Air Nozzle and a 72” extension.  The Soft Grip Safety Air Gun is constructed of cast aluminum and includes a hook for hanging in a convenient location. The Model # HP1125, 2” High Power Flat Super Air Nozzle, produces 2.2 lbs. of force @ 80 PSIG and utilizes 37 SCFM with a sound level of 83 dBA. This would also meet or exceed the OSHA standards for safety, per Standard 1910.242(b) for 30 psi dead end pressure, and allowable noise exposure per Standard 29 CFR – 1910.95(a).

HP1230
An EXAIR model HP1230 Soft Grip Safety Air Gun

To discuss your application or help with selecting the right product, contact an application engineer.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN