Robert Boyle And The Scientific Method

How do we know something is true? In grade school, you may remember being taught a process by which an observation elicits a question, from which a hypothesis can be derived, which leads to a prediction that can be tested, and proven…or not) These steps are commonly known as the Scientific Method, and they’ve been successfully used for thousands of years, by such legendary people of science as Aristotle (384 – 322 BC,) Roger Bacon (1219 – 1292,) Johannes Kepler (1571-1630,) Galileo Galilei (1564-1642) and right up to today’s scientists who run the CERN Large Hadron Collider.  The collider is the largest machine in the world, and its very purpose is the testing and proving (or not) of hypotheses based on questions that come from observations (often made in the LHC itself) in ongoing efforts to answer amazingly complex questions regarding space, time, quantum mechanics, and general relativity.

The Scientific Method is actually the reason (more on this in a minute) for the name of a fundamental law of physics: Boyle’s Law.  It states:

“For a fixed amount of an ideal gas kept at fixed temperature, pressure and volume are inversely proportional.”

And can be mathematically represented:

PV=k, where:

  • P = is the pressure of a gas
  • V = is the volume of that gas, and
  • k = is a constant

So, if “k” is held constant, no matter how pressure changes, volume will change in inverse proportion.  Or, if volume changes, pressure will change in inverse proportion.  In other words, when one goes up, the other goes down.  It’s also quite useful in another formulaic representation, which allows us to calculate the resultant volume (or pressure,) assuming the initial volume & pressure and resultant pressure (or volume) is known:

P1V1=P2V2, where:

  • P1  and P2 are the initial, and resultant, pressures (respectively) and
  • V1  and V2 are the initial, and resultant, volumes (respectively)

This is in fact, what happens when compressed air is generated, so this formula is instrumental in many aspects of air system design, such as determining compressor output, reservoir storage, pneumatic cylinder performance, etc.

Back to the reason it’s called “Boyle’s Law” – it’s not because he discovered this particular phenomenon.  See, in April of 1661, two of Robert Boyle’s contemporaries, Richard Towneley and Henry Power, actually discovered the relationship between the pressure and volume of a gas when they took a barometer up & down a large hill with them.  Richard Towneley discussed his finding with Robert Boyle, who was sufficiently intrigued to perform the formal experiments based on what he called “Mr Towneley’s hypothesis.”  So, for completing the steps of Scientific Method on this phenomenon – going from hypothesis to law –  students, scientists, and engineers remember Robert Boyle.

Russ Bowman
Application Engineer
EXAIR Corporation
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IMGP6394 image courtesy of Matt Buck, Creative Commons License

Starting a Leak Prevention Program

Since all compressed air systems will have some amount of leakage, it is a good idea to set up a Leak Prevention Program.  Keeping the leakage losses to a minimum will save on compressed air generation costs,and reduce compressor operation time which can extend its life and lower maintenance costs.

SBMart_pipe_800x

There are generally two types of leak prevention programs:

  • Leak Tag type programs
  • Seek-and-Repair type programs

Of the two types, the easiest would be the Seek-and-Repair method.  It involves finding leaks and then repairing them immediately. For the Leak Tag method, a leak is identified, tagged, and then logged for repair at the next opportune time.  Instead of a log system, the tag may be a two part tag.  The leak is tagged and one part of the tag stays with the leak, and the other is removed and brought to the maintenance department. This part of the tag has space for information such as the location, size, and description of the leak.

The best approach will depend on factors such as company size and resources, type of business, and the culture and best practices already in place. It is common to utilize both types where each is most appropriate.

A successful Leak Prevention Program consists of several important components:

  • Baseline compressed air usage – knowing the initial compressed air usage will allow for comparison after the program has been followed for measured improvement.
  • Establishment of initial leak loss – See this blog for more details.
  • Determine the cost of air leaks – One of the most important components of the program. The cost of leaks can be used to track the savings as well as promote the importance of the program. Also a tool to obtain the needed resources to perform the program.
  • Identify the leaks – Leaks can be found using many methods.  Most common is the use of an Ultrasonic Leak Detector, like the EXAIR Model 9061.  See this blog for more details. An inexpensive handheld meter will locate a leak and indicate the size of the leak.

    ULD_Pr
    Using the Model 9061 Ultrasonic Leak Detector to search for leaks in a piping system
  • Document the leaks – Note the location and type, its size, and estimated cost. Leak tags can be used, but a master leak list is best.  Under Seek-and-Repair type, leaks should still be noted in order to track the number and effectiveness of the program.
  • Prioritize and plan the repairs – Typically fix the biggest leaks first, unless operations prevent access to these leaks until a suitable time.
  • Document the repairs – By putting a cost with each leak and keeping track of the total savings, it is possible to provide proof of the program effectiveness and garner additional support for keeping the program going. Also, it is possible to find trends and recurring problems that will need a more permanent solution.
  • Compare and publish results – Comparing the original baseline to the current system results will provide a measure of the effectiveness of the program and the calculate a cost savings. The results are to be shared with management to validate the program and ensure the program will continue.
  • Repeat As Needed – If the results are not satisfactory, perform the process again. Also, new leaks can develop, so a periodic review should be performed to achieve and maintain maximum system efficiency.

In summary – an effective compressed air system leak prevention and repair program is critical in sustaining the efficiency, reliability, and cost effectiveness of an compressed air system.

If you have questions about a Leak Prevention Program or any of the 16 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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Video Blog: EXAIR’s Efficiency Lab

If you’d like to know how efficient (or not,) quiet (or not,) and effective (or not) your current compressed air devices are, the EXAIR Efficiency Lab can help.  For more details, we hope you’ll enjoy this short video.

If you’d like to talk about getting the most out of your compressed air system, we’d love to hear from you.

Russ Bowman
Application Engineer
EXAIR Corporation
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Ultrasonic Leak Detector: Because Leaks Won’t Find (Or Fix) Themselves

I once worked in an equipment repair shop with a small and simple compressed air system…just a 5HP single acting piston compressor that sat atop a 50 gallon tank, in the corner by “The Big Truck”. The majority of our work was field service, and management was big on maintaining our service trucks, so we checked tire pressures every Monday morning as we rolled out, and kept a tire chuck handy to ensure proper inflation. It was also used to supply a couple of air guns that were used at our drill press and soldering/assembly station. One morning, I noticed the air compressor was running when I arrived…I thought it was odd, because I knew for a fact it hadn’t been used in at least 16 hours, but that compressed air went someplace, right? We had a leak. Well, at least one.

This was mid-December, and the week between Christmas and New Year’s Day was characteristically slow, and typically devoted to a thorough shop cleaning. We also took the opportunity to get some bottles of soapy water and check for leaks at the handful of pipe fittings that comprised the system…for the uninitiated, if you have a leaky fitting, the escaping air blows bubbles in the soapy water (a cheap, messy way in other words). We found some bubbling, undid those fittings, cleaned them, and applied fresh pipe thread sealant (I don’t want to start any arguments, but I was taught that tape is more of a thread protectant than an effective sealing agent) and, in addition to replacing a couple of well-worn hoses, we were up and running.  And we never heard the compressor running first thing in the morning again.

Not all compressed air systems are as simple as that, though.  Many go from a room with several large & sophisticated air compressors, to corners of every building on the grounds.  Through valves & manifolds, to cylinders, machinery and blow offs, with more connections than you could soap-and-water check in a month.

In those cases, the EXAIR Model 9061 Ultrasonic Leak Detector makes short(er) work of finding the leaks.  With both visual (LED’s on the face) and audible (headphones) indications, even very small leaks are easy to detect with the parabola installed.  The precise location can then be found with the tubular extension.

EXAIR Ultrasonic Leak Detector “hones in” on the exact location of a leak in a compressed air line.

You’ll still have to fix the leaks yourself, but finding them is oftentimes more than half the battle.  And, once fixed, it can be worth a million (cubic feet of compressed air, that is.)

EXAIR’s Ultrasonic Leak Detectors are not only useful for finding compressed air leaks; they’re popular in a variety of other areas:

Additionally, they can be used to identify faulty bearings, brake systems, tire & tube leaks, engine seals, radiators, electrical relay arcing…anything that generates an ultrasonic sound wave.  If you’d like to find out more, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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How to Estimate Leaks and the Impact upon a Compressed Air System

In today’s age where compressed air is often referred to as the 4th utility in an industrial manufacturing facility, leaks throughout the system can add up to serious financial losses. It has been estimated that leaks can waste as much as 20-30 percent of an air compressor output.

waste

Not only are leaks a source of wasted energy, they can also contribute to other losses such as:

  • Causing a drop in system pressure, resulting in air tools to function less efficiently
  • Increasing the air compressor on/off cycles which shortens the life of it and other components in the system
  • Increased maintenance costs and more planned downtime for the maintenance to be performed
  • A need to install of additional compressors to make up for the inefficiencies caused by leaks

For compressors that have start/stop controls – the below formula can be used to estimate the leakage rate in the system-

Leakage Equation 1

To use the above formula, the compressor is started when there is no demand on the system –  all air operated equipment and devices are turned off.  As the air escapes the system through the leaks, the system pressure will drop and the compressor will turn on and cycle to bring the pressure back up to the operating level. Measurement of the average time (T) of compressor run duration, and time (t) of the system pressure to drop to the set-point can be plugged into the formula and a Leakage Percentage established.

Another method to estimate the leakage rate is shown below-

Leakage Equation 2

The above method requires knowledge of the total system volume, which includes downstream air receivers, air mains, and all piping.  To perform the check, bring the system pressure up the normal operating pressure (P1) and then measure the time (T) it takes for the system to drop to pressure (P2) which is generally around half the operating pressure.  The 1.25 is a correction factor to normal system pressure, since the leakage rate will be less as the system pressure is lowered.

A leakage rate greater than 10% typically shows that there are areas of improvement (leaks that can be identified and repaired)

Any leakage testing and estimating should be preformed regularly, at least each quarter, so as to minimize the effect of any new system leaks. The tests are only one part of a leak detection and repair program. The best way to detect leaks is the use of ultrasonic leak detector (shown below.)  To learn more about the EXAIR model 9061 Ultrasonic Leak Detector, check out this blog that was previously published.

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If you have questions about compressed air systems, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, 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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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

EXAIR Optimization Products: Ultra Sonic Leak Detector Overview

Ultrasonic Leak Detector

The Ultrasonic Leak Detector is a hand-held, high quality instrument that can locate costly leaks in a compressed air system.  When using the Ultra Sonic Leak Detector, you only need to aim it in the direction of the suspected leak and if a leak is present an audible tone can be heard through the supplied headphones and the LED will light.  This can be accomplished from up to 20′ away!

If you are not maintaining your compressed air system you can easily waste up to 30% of your compressor’s output through leaks.  We all know compressed air is expensive, so mitigating wasteful leaks should be high on your to do list!

 

ultrasonic_2
EXAIR Ultrasonic Leak Detector

What is Ultrasound

Since most compressed air leaks emit only Ultra Sonic sound it would be next to impossible to find a leak by listening for them since the sound is above the human thresh hold.   That is where the EXAIR Ultrasonic Leak Detector comes in.  Its sensitivity is is adjustable with 3 settings X1, X10 and X100 along with an on/off thumb wheel for fine sensitivity adjustments.  The Ultra Sonic Leak Detector also comes with both a parabola or tubular extension to aim the unit and block out extraneous background noise.

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.

If you would like to discuss the Ultra Sonic Leak Detector or any EXAIR product, I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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