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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Cleaning Glass After a Cutting Machine, Super Air Knives to the Rescue

Glass cutting machine

A glass cutting facility was having issues with small shards of glass leaving the cutting machine.  After scribing and breaking individual panes, small pieces of glass would come apart from the edges of the glass.  These glass fragments would go downstream causing cuts on transport wheels as well as creating blemishes in the surface of the glass.  They needed a non-contact way to clean the glass as the panes left the cutting machine.

Their operation started with a 156” (3.96m) wide sheet of glass placed at the front of the cutting machine.  The glass was moved into the machine where it would scribe different dimensions and sizes to minimize any scrap.  As the machine was scribing, a protective separator would close off the cutting machine to protect the operators.  Once finished, the protective separator would open, allowing the glass sheet to exit on the other side of the machine.  As the glass was coming out, a break device would “crack” the glass panes on the scribed lines.  They wanted to clean the surface as the glass sheet was coming out to keep the fragments in the machine.

EXAIR Super Air Knife model 1100108

EXAIR has always been the leader in manufacturing the longest air knives in the industry.  The EXAIR Super Air Knives can be manufactured up to 108” (2.74m) long in one continuous length.  But, for this application, we had to tackle it in a different manner to reach across the entire width of 156” (3.96m).  EXAIR had a solution, the model 110900 Coupling Bracket Kit.  This can combine aluminum Super Air Knives for additional length.  It has all the hardware to securely attach the Super Air Knives end-to-end to get a continuous air flow along the entire length.  With the Coupling Bracket Kit, I recommended a model 110072, 72” (1.83m) long aluminum Super Air Knife with a model 110084, 84” (2.13m) aluminum Super Air Knife.  The customer was now able to clean the entire section of glass just in front of the exit of the cutting machine.  With the air knives directed to blow at a slight angle in the counter-flow direction, this non-contact form of cleaning was able to keep the shards inside the machine without scratching the surfaces.

Air Knife Coupling Bracket Kit

The Super Air Knives are designed to be the most efficient air knives in the market place.  It has a 40:1 amplification ratio which entrains 40 parts of ambient air to every 1 part of compressed air.  So, it will save you compressed air which in turn, will save you money.  Here at EXAIR, we like to go one step further for our customers.  EXAIR offers an Optimization product line to save the customer even more money, to reduce even more waste, and to become even more energy efficient.  For this customer above, I recommended an Electronic Flow Control, EFC.  This uses a photoelectric sensor to turn on a system only when compressed air is needed.  It is a small PLC unit with a timer control.  I recommended the model 9064-2 which has two solenoid valves to operate each Super Air Knife.  The photoelectric sensor can be adjusted for light and dark object, but for glass, we had to look for an alternative way.  I was able to have the customer place it on the protective separator.  Now, the Super Air Knives will remain turned off until after the scribing was completed. When the separator moved up, it would trigger the timing operation of the EFC.  By adding the EFC to their system, they were able to reduce the amount of compressed air by one-half.

click on picture for mor information

If you have a wide area that needs to be blown off, cooled, or dried; EXAIR may have a solution for you.  For the customer above, EXAIR was able to combine Super Air Knives with optimization for an efficient and effective way to clean a wide surface.  If you would like to discuss a solution for your “wide” application, you can contact an Application Engineer at EXAIR to discuss.

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

An Ultrasonic Leak Detector Helps with a Pressure Decay Leak Detector

Ultrasonic Leak Detector

A manufacturing company had a pressure decay leak system to check for leaks in compressed air housings.  Their detector was able to find leaks as small as 0.02 cc/min.  The leak program was designed for recording each housing with a batch/lot number and the corresponding leak data.  If the housing reached or surpassed the leak limit, the part would be marked and quarantined.  The pressure decay leak detector was a sensitive instrument, but it could not tell the operator where the leak was occurring.

How the pressure decay leak detector worked was by pressurizing the housing to a target pressure.  The flow valves would shut, isolating the housing.  After the pressure stabilized, the sensitive pressure sensors would pick up any loss in pressure over time.  If the leak limit wasn’t reached, a green light would indicate a good leak test.  If the limit was reached, a red light would indicate a failed leak test, and the housing would have to be segregated.

Reference Filter Housing

The housing design used a head, a bowl, a drain, and a differential pressure gauge.  The leak paths were numerous.  It could be at the drain, between the drain and the bowl, between the head and bowl, at the differential pressure gauge, and even in the casting of the head.  The heads were made from a die-casted aluminum.  If the process was not done properly, porosity could occur in the head.  The leak detector was sensitive enough to find any voids that would allow air to pass through the head casting.  With these many areas of potential leaks, it could be problematic if the reject rate was high.

For the application above, it is important to find where the leaks are occurring in order to create a corrective action.  In order to find the leaks, they purchased a model 9061 Ultrasonic Leak Detector from EXAIR.  Instead of pressure decay, the Ultrasonic Leak Detector uses sound.  Whenever a leak occurs, it will generate an ultrasonic noise.  These noises have a range of frequencies from audible to inaudible.  The frequencies in the range of 20 Khz to 100 Khz are above human hearing, and the Ultrasonic Leak Detector can pick up these high frequencies, making the inaudible leaks, audible.  The model 9061 has three sensitivity ranges and a LED display; so, you can find very small leaks.  This unit comes with two attachments.  The parabola attachment can locate leaks up to 20 feet (6.1 meters) away.  And the tube attachment can define the exact location.  With this application, they used the tube attachment to locate the leaks.  After retesting the failed housings, they found that 80% of the rejects were from a sealing surface.  They were able to replace or repair the o-rings.  10% of the leaks were coming from the drain.  3% of the rejects were leaking at the differential pressure gage.  Both the drains and the pressure gages could be replaced with new units.  7% of the housings had a porosity problem in the head of the housing.  For these, they were shipped back for evaluation to create a modification for a better casting.  The production manager shared with me that an extra vent hole was required to reduce the void.  This was a huge savings for the die-caster and manufacturing plant.

EXAIR Ultrasonic Leak Detector is a great tool.  It can be used in a variety of applications including compressed air systems, bearing wear, circuit breakers, refrigerant leaks, and gas burners to name few.  For the company above, it was a great tool to improve their assembly and testing process for their housings.  If you have an application where you need to find an ultrasonic noise, you can speak with an Application Engineer to see if the model 9061 Ultrasonic Leak Detector could help.

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

Turn The Pressure Down & Save Money

In the past your typical industrial air compressor was rated to run at 100 psi and it was not often that this pressure was exceeded.  Lately with modern advances pressures have slowly crept up and have surpassed this threshold.  Unfortunately this has proven costly to the industrial user of compressed air.

To clarify this point, if a compressed air system is set to maintain 102 psi it will cost the plant 1% more in electric costs than if the system ran at 100 psi.  Also noteworthy is that unregulated air demands consume about 1% more flow for every psi of additional pressure.

So why is the air pressure getting so high and what can you do about it?  Here are some possible causes and solutions:

Devices that do require more than 100 psi:  It may not be the pneumatic device at all. If these devices are connected with restrictive fittings or there are excessive leaks in the system this can cause up to a 30 psi increase in line pressure just to make up for the poor piping. If this can be corrected it is possible that the pressure can be reduced.

EXAIR offers the Ultrasonic Leak Detector to facilitate tracking down hard to find system leaks and a wide variety of Air KnivesAir Amplifiers, Super Air Wipes, Air Nozzles, Line Vacs, Vacuum Generators and all of them are engineered to provide peak performance at 80 psi and make efficient use of compressed air. Though it is not uncommon for these products to provide a solution at much less pressure.

9061
EXAIR 9061, Ultrasonic Leak Detector

Applications that are believed to be high pressure:  Plant workers sometimes think that a higher air pressure is required than actually necessary.  This can be caused by a lack of training or perhaps the trainers are simply repeating what they have been taught in error.  It is good practice to review all locations that are using a higher pressure to determine if it is really necessary.

Loss due to undersize pipes:  If your plants compressed air supply lines are undersized for the volume demand, this can cause a significant restriction and raise the line pressure.  The EXAIR Digital Flow Meter can assist in recording how much demand is for a given point in time which will clarify usage.

9093
EXAIR Digital Flow Meter

 

Filter/Dryer restrictions:  If the Dryer or Filter/Separators are dirty and/or undersized the compressor operating pressure is typically raised to overcome these restrictions.  EXAIR has six sizes of Filter/Separators to ensure they are properly sized for the SCFM required by the devices that are connected to them.  Five of the models feature an automatic drain system and of course we carry the replacement filter elements and rebuild kits to keep them in top operating condition.

Temporary demands: There may be occasional peak compressed air demands in the plant that may be caused by a different or special compressed air process or machine. If the demand is greater than the supply, the pressure may be pulled down to unacceptably low levels.  In an attempt to make up for the increased demand a plant may raise the operating pressures.  The best way to cope with temporary demands is to install a receiver tank that stores compressed air that can be released when the demand calls for it.

receiver_tank
EXAIR 9500-60, 60 Gallon Receiver Tank

Factory default settings:  It is common for compressor manufacturers to set the air pressure at or very near the maximum pressure rating for that compressor.  There is no reason for this other than to verify that the air compressor will perform at its rated maximum pressure.  To save on air and maintenance costs the compressor should be set only as high as the maximum pressure for approved uses in the facility.

In the compressed air industry, EXAIR provides tools and products with quick payback times.

If you would like to discuss increasing the efficiency of your compressed air usage, quieter compressed air products and/or any EXAIR product,  I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Optimizing Your Current Compressed Air System Is Simple

A few weeks ago, we posted a blog discussing how artificial demand and leaks can lead to poor performance and expensive waste.  Today, I’d like to review how following a few simple steps can help optimize your current compressed air system and reduce compressed air usage.

The first step you want to consider is measuring the air usage in the system. To do this, you want to start at the compressor and check individual leads to each drop point to a blowoff device, record your findings to track the demand. By measuring your compressed air usage, you can locate the source of high usage areas and monitor the usage on each leg of the system. If the demand exceeds the supply, there is potential for problems to arise, such as lowered pressure and force from compressed air operated devices leading to irregular performance.

Digital Flowmeter with wireless capability

EXAIR’s Digital Flowmeters are designed to measure flow continuously and accurately to give you real-time flow measurements of your compressed air system to help identify problems areas.

Step 2 is to locate the source of waste. Again, compressed air leaks can result in a waste of up to 30% of a facility’s compressor output. A compressed air leak detection and repair program can save a facility this wasted air. Implementing such a program can be used as a way for a facility to “find” additional air compressor capacity for new projects. Whenever a leak occurs, it will generate an ultrasonic noise.

Model # 9061 Ultrasonic Leak Detector

Our Ultrasonic Leak Detector is designed to locate the source of ultrasonic sound emissions up to 20’ away. These ultrasonic sound emissions are converted to a range that can be heard by humans. The sound is 32 times lower in frequency than the sound being received, making the inaudible leaks, audible through the included headphones and the LED display gives a visual representation of the leak.

The 3rd step involves finding the source of noisy and wasteful blowoffs, like open pipes or homemade blowoffs, and replacing them with an energy efficient, engineered solution. By replacing these devices, you are not only reducing the amount of waste but also improving operator safety by complying with OSHA safety requirements.

Model # 9104 Digital Sound Level Meter

EXAIR’s Digital Sound Level Meter is an easy to use instrument that measures and monitors the sound level pressure in a wide variety of industrial environments. The source of loud noises can be quickly identified so that corrective measures can be taken to keep sound levels at or below OSHA maximum allowable exposure limits.

The easiest way to reduce compressed air usage and save on operating expense is to turn off the compressed air to a device when it isn’t needed, step 4 in the process. Not only will this save money, in many cases, it can also simplify a process for the operator.

 

Sizes from 1/4″ NPT up to 1-1/4″ NPT are available

A simple manual ball valve and a responsible operator can provide savings at every opportunity to shut down the air flow.

 

120VAC, 240VAC or 24VDC

 

For automated solutions, a solenoid valve can be operated from a machine’s control. For example, if the machine is off, or a conveyor has stopped – close the solenoid valve and save the air.

 

 

Model # 9040 Foot Valve

A foot pedal valve offers a hands free solution to activate an air operated device only when needed, such as being implemented in an operator’s work station.

 

EFC – Electronic Flow Control

For even more control, you can use a device like our EFC or Electronic Flow Control. This helps minimize compressed air usage by incorporating a programmable timing controlled (0.10 seconds to 120 hours) photoelectric sensor to turn off the compressed air supply when there are no parts present. It is suited for NEMA 4 environments and can be easily wired for 100-240VAC.

 

 

Step 5, intermediate storage. Some applications require an intermittent demand for a high volume of compressed air. By installing a receiver tank near the point of high demand, there is an additional supply of compressed air available for a short duration. This will help eliminate fluctuations in pressure and volume.

Model # 9500-60

EXAIR offers a 60 gallon, ASME approved vertical steel tank with mounting feet for easy installation near high demand processes.

Many pneumatic product manufacturers have a certain set of specifications regarding performance at stated input pressures. In many applications, or in the case of using a homemade blowoff device like open pipe, these wouldn’t necessarily require the full rated performance of the device or full line pressure. Controlling the air pressure at the point-of-use device will help to minimize air consumption and waste, step 6.

Pressure Regulators permit easy selection of the operating pressure

By simply installing a pressure regulator on the supply side, you can start off at a low pressure setting and increase the pressure until the desired result is achieved. Not only will this help to conserve energy by only using the amount of air required for the application, it also allows you to fine tune the performance of the point-of-use device to match the application requirements.

If you have any questions, please contact an application engineer at 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

A Unique Application for the Ultrasonic Leak Detector

Here on the EXAIR blog we post a ton of different applications for our products. We typically see similar applications each day and write about them so that you may identify potential points in your various processes that may benefit from an engineered compressed air solution. Many of these are typical blowoff or cooling applications that we see day in and day out. Sometimes, though, we see some applications that are outside the realm of typical operation. This can sometimes require the manufacturing of a specialized part or just getting a little creative with a stock product.

Our distributor in Argentina recently contacted me about a unique application for an Ultrasonic Leak Detector. The Model 9061 Ultrasonic Leak Detector is a hand-held instrument that allows you to locate costly leaks in a compressed air distribution system. As pressurized air exits a small orifice, an ultrasonic sound that is above human hearing is created. The Ultrasonic Leak Detector is able to pick up on these sound emissions and can convert it to an audible range that is able to be heard by the human ear. Typically, this product is used in conjunction with a leak prevention program to help save money and compressed air by identifying leaks in the distribution system.

ultrasonic_2
Model 9061 ULD detecting a leak

The customer is a manufacturer of plastic bottles used to hold a wide variety of different personal care products. The bottles were molded in two separate pieces, then brought together and sealed. After the two pieces of the bottle were sealed, they had to test each one to ensure that they remained watertight. Their current method involved filling the cavities with water and inspecting for leaks.

While this method was effective, when a leak was present water would get all over the machine and floor and needed to be cleaned up. This to them was considered a nuisance and they began to explore alternative methods of checking the seals on the bottles. They found EXAIR’s Ultrasonic Leak Detector and wondered if they could use it to detect leaks on the bottles if they were to pressurize them with compressed air instead of filling them with water. We’ve handled similar applications in the past, this one here a customer used the ULD to detect leaks from poor welds on the roof of buses. They ordered one for testing and were very pleased with the results. The ULD had no problem detecting leaks in the bottles and allowed them to eliminate the mess and annoyance associated with using water.

2
Operator testing for leaks using the ULD

Just because you can’t find a particular application in our Application Database on the website or here on the blog, doesn’t mean that it can’t be done! With our unconditional 30 day guarantee for all stock products you have plenty of time to test it out in your specific application. If for any reason it won’t work for you, just send it back and we’ll try something else.

If you have a unique application that could be served by an Intelligent Compressed Air Product, give us a call. Trust me when I say we absolutely LOVE tackling a new and exciting challenge with a creative solution!

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

Six Steps To Optimizing Your Compressed Air System – Step 1: Measure

“To measure is to know – if you cannot measure it, you cannot improve it.”
-Lord Kelvin, mathematical physicist, engineer,and pioneer in the field of thermodynamics.

This is true of most anything. If you want to lose weight, you’re going to need a good scale. If you want to improve your time in the 100 yard dash, you’re going to need a good stopwatch. And if you want to decrease compressed air consumption, you’ll need a good flowmeter. In fact, this is the first of six steps that we can use to help you optimize your compressed air system.

Six Steps To Optimizing Your Compressed Air System

There are various methods of measuring fluid flow, but the most popular for compressed air is thermal mass air flow.  This has the distinct advantage of accurate and instantaneous measurement of MASS flow rate…which is important, because measuring VOLUMETRIC flow rate would need to be corrected for pressure in order to determine the true compressed air consumption.  My colleague John Ball explains this in detail in a most excellent blog on Actual (volume) Vs. Standard (mass) Flows.

So, now we know how to measure the mass flow rate.  Now, what do we do with it?  Well, as in the weight loss and sprint time improvements mentioned earlier, you have to know what kind of shape you’re in right now to know how far you are from where you want to be.  Stepping on a scale, timing your run, or measuring your plant’s air flow right now is your “before” data, which represents Step One.  The next Five Steps are how you get to where you want to be (for compressed air optimization, that is – there may be a different amount of steps towards your fitness/athletic goals.)  So, compressed air-wise, EXAIR offers the following solutions for Step One:

Digital Flowmeter with wireless capability.  This is our latest offering, and it doesn’t get any simpler than this.  Imagine having a flowmeter installed in your compressed air system, and having its readings continually supplied to your computer.  You can record, analyze, manipulate, and share the data with ease.

Monitor your compressed air flow wirelessly over a ZigBee mesh network.

Digital Flowmeter with USB Data Logger.  We’ve been offering these, with great success, for almost seven years now.  The Data Logger plugs into the Digital Flowmeter and, depending on how you set it up, records the flow rate from once a second (for about nine hours of data) up to once every 12 hours (for over two years worth.)  Pull it from your Digital Flowmeter whenever you want to download the data to your computer, where you can view & save it in the software we supply, or export it directly into Microsoft Excel.

From the Digital Flowmeter, to your computer, to your screen, the USB Data Logger shows how much air you’re using…and when you’re using it!

Summing Remote Display.  This connects directly to the Digital Flowmeter and can be installed up to 50 feet away.  At the push of a button, you can change the reading from actual current air consumption to usage for the last 24 hours, or total cumulative usage.  It’s powered directly from the Digital Flowmeter, so you don’t even need an electrical outlet nearby.

Monitor compressed air consumption from a convenient location, as well as last 24 hours usage and cumulative usage.

Digital Flowmeter.  As a stand-alone product, it’ll show you actual current air consumption, and the display can also be manipulated to show daily or cumulative usage. It has milliamp & pulse outputs, as well as a Serial Communication option, if you can work with any of those to get your data where you want it.

With any of the above options, or stand-alone, EXAIR’s Digital Flowmeter is your best option for Step One to optimize your compressed air system.

Stay tuned for more information on the other five steps.  If you just can’t wait, though, you can always give me a call.  I can talk about compressed air efficiency all day long, and sometimes, I do!