Sound Power Vs Sound Pressure

sound-level-comparison
EXAIR Intelligent Compressed Air Product dBA ratings as compared to other sounds

When trying to explain or state a number associated with how loud a sound or noise is it can be somewhat confusing or at the very least, ambiguous.  This blog will help to make it clear and easy to understand the difference between Sound Power and Sound Pressure.

Sound Power is defined as the speed at which sound energy is radiated or transmitted for a given period of time.  The SI unit of sound power is the watt. It is the power of the sound force on a surface of the medium of propagation of the sound wave.

Sound Pressure is the sound we hear and is defined as the atmospheric pressure disturbance that can vary by the conditions that the sound waves encounter such as furnishings in a room or if outdoors trees, buildings, etc.  The unit of measurement for Sound Pressure is the decibel and its abbreviation is the dB.

I know, the difference is still clear as mud!  Lets consider a simple analogy using a light bulb.  A light bulb uses electricity to make light so the power required (stated in Watts) to light the bulb would be the “Sound Power” and the light generated or more specific the brightness is the “Sound Pressure”.  Sound just as with the light emitting from the bulb diminishes as the distance increases from the source.  Skipping the math to do this, it works out that the sound decreases by 6 dB as the distance from the sound source is doubled.  A decrease of 3dB is half as loud (Sound Pressure) as the original source.  As an example sound measured at 90 dB @ 36″ from the source would be 87dB at 54″ from the sound source or 84dB at 72″.

We at EXAIR specialize in making quiet and efficient point of use compressed air products, in fact most of our products either meet or exceed OSHA noise standards seen below.

OSHA Noise Level

EXAIR also offers the model 9104 Digital Sound Level Meter.  It is an easy to use instrument for measuring and monitoring the sound level pressures in and around equipment and other manufacturing processes.

If you have questions about the Digital Sound Level Meter, or would like to talk about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR or any Application Engineer.

Steve Harrison
Application Engineer

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EXAIR Products: Silencing Mufflers Overview

OSHA Standard 29 CFR 1910.95(a), relating to permissible noise exposure levels, states that when employees are subjected to sounds in excess of 90 dBA, some type of control should be used to reduce the sound level. In an industrial setting, it’s very common to find the exhausting air from air operated devices such as actuators, diaphragm pumps or cylinders for example, to produce sound levels well above the allowable limits set forth in the Standard. EXAIR offers a variety of different Silencing Mufflers that help to reduce this  noise level, while also increasing operator safety.

 

Reclassifying Mufflers are available in 1/8″, 1/4″, 3/8″, 1/2″, 3/4″ and 1″ NPT sizes

EXAIR’s Reclassifying Mufflers offer noise reduction up to 35 dB and are available in sizes ranging from 1/8″ to 1″ NPT. These types of mufflers are often considered”dual-purpose” as they not only reduce the noise level but also remove oil from the exhaust airflow by incorporating a removable filter element.  The exhausting oil mist is reduced from 50 PPM (parts per million) to only 0.015 PPM, when the device is operated at 100 PSIG. In addition, there is a bowl on the bottom to capture any residual oil and a 1/4″ tube adaptor to allow for easy draining.

Sintered Bronze Mufflers are available in #10-32, 1/8″, 1/4″, 3/8″, 1/2″, 3/4″, 1″, 1-1/4″ and 1-1/2″ NPT sizes, as well as 1/2-20 UNF female for use with solenoid valves
Straight Through Mufflers are available in 1/4″, 3/8″ and 3/4″ MNPT x FNPT

Sintered Bronze Mufflers are a relatively low cost option, commonly used with air cylinders as they can be installed quick and easy. We offer 1o different sizes, ranging from #10-32 for small installations, up to 1-1/2″ NPT for larger scale applications. The noise reduction depends on the size of the muffler and back pressure, which can occur from dirt or particulate clogging the muffler, restricting the exhausting airflow from passing through the porous sintered bronze.

Our Straight Through Mufflers are made of corrosion resistant aluminum and are lined with a sound absorbing foam, capable of reducing noise levels up to 20 dB. We offer 3 different sizes, 1/4″, 3/8″ and 3/4″ NPT, with a male thread on one end and female thread on the other. We incorporate this muffler design into our Cold Guns and Adjustable Spot Coolers and they are commonly used with our Vortex Tubes, Cabinet Cooler® Systems and E-Vac® Vacuum Generators as well.

Heavy Duty Mufflers are available in 1/4″ and 3/8″ FNPT

Lastly, the Heavy Duty Mufflers feature an internal, 50 mesh stainless steel screen, to protect against contaminants in the airflow,  and a corrosion resistant aluminum outer shell. In most cases, the sound reduction can be as high as 14 dB and we offer 2 different sizes, 1/4″ and 3/8″ FNPT. These types of mufflers are regularly used on the hot air exhaust of our Vortex Tubes.

For help with product selection or to discuss a particular process, please contact one of our application engineers at 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Award Winning Compressed Air Nozzle Saves Hundreds of Dollars Annually

awards2013_1126_400wide

 

EXAIR’s 1 Inch Flat Super Air Nozzle won the Gold Award for Compressed Air from Plant Engineering in 2014. We won the award for the immense savings that our customers reap by using this nozzle to replace open blow offs. While saving compressed air, we also reduce noise level and comply with an OSHA regulation 192.242(b).  Do not leave that blow off open. It is costing you everyday in dollars; it may cost you more in OSHA fines later, and it will cost your employees hearing later.

A 1/4″ copper tube can use 33 SCFM at 80 PSIG of inlet pressure. This homemade blow off will use 1,980 standard cubic feet per hour. Typical industrial compressed air cost $0.25 per 1,000 standard cubic feet.  That 1/4 copper tube is costing you $0.50 every hour to run. Each year, one 1/4″ copper tube costs $2,970*.

The 1 inch Flat Super Air Nozzle, model 1126, uses 10.5 SCFM or 22.5 SCFM less than 1/4″ Copper tube.  Saving your company 22.5 SCFM, is the same as saving $0.34 every hour or $2,025 every year.*  Saving 22.5 SCFM also, means that your compressor system doesn’t have to work as hard.  A 5 HP compressor will put out 20 SCFM, so replacing one 1/4″ Copper Tube with a model 1126 will save you from upgrading compressor system as your company expands.

Regardless of the $2,025 you just saved by replacing the homemade blow offs with engineered nozzle, it is also an industry best practice because it can lower the noise exposure for personnel and prevent any harm from dead end pressure.  OSHA standard 29 CFR – 1910.95(a) requires that if an employee is exposed to greater than 100 dBA for 2 hours, he or she needs to wear hearing protection.  A 1/4″ copper tube will easily exceed 100 dBA.  The model 1126 will lower the noise level to 77 decibel, 13 dBA lower than the OSHA requirements for an 8 hour day.

Finally, the 1″ Flat Super Air Nozzle cannot be dead ended, which protects your employees from serious injury. In the event, that a compressed air orifice is blocked with no means of escape, air may enter the bloodstream from an open cut or wound in the skin. Compressed air must be kept below 30 PSIG to eliminate this danger when using an open pipe, tube or many commercial air nozzles. With EXAIR nozzles, pressure to the nozzle  can remain at line pressure and produce the maximum velocity and force for a successful application.

*Assuming 24 hours a day and 250 working days

Dave Woerner
Application Engineer
Davewoerner@EXAIR.com
@EXAIR_DW