The Super Air Knife and the Amplification Ratio

Super Air Knife

The EXAIR Super Air Knife has a 40:1 amplification ratio.  So, what does this mean?  The definition of ratio is a relation between two amounts showing the number of times one value is contained within the other.  For the Super Air Knife, it is a value that shows the amount of ambient air that is drawn into the compressed air.  With an amplification ratio of 40:1, that means that there are 40 parts of ambient air for every 1 part of compressed air; which helps make the most efficient air knifes available in the market.

Super Air Knife has 40:1 Amplification Ratio

Most people think that compressed air is free, but it is most certainly not.  Because of the amount of electricity required, compressed air is considered to be the fourth utility for manufacturing plants.  To save on utility costs, it is important to use compressed air very efficiently.  So, the higher the amplification ratio, the more efficient the compressed air product.  Manufacturing plants that use open fittings, copper tubes, and drilled pipes for blowing are not efficiently using their compressed air system.  These types of products generally have between a 5:1 to 10:1 amplification ratio.  When EXAIR began, they knew that there was a better way in saving compressed air by increasing the amplification ratio.

EXAIR initially created a line of air knives called the Standard Air Knife and Full-Flow Air Knife.  They utilize a Coanda effect to blow air at a 30:1 amplification ratio.  These air knives were much more efficient for blowing air than the open fittings, tubes and drilled pipes.  But, EXAIR knew that we could design a more efficient air knife, the Super Air Knife which has a 40:1 amplification ratio.

I like to explain things in every day terms.  For this analogy, the amplification ratio can be represented by gas mileage.  Like your car, you want to get the most distance from a gallon of gas.  With your compressed air system, you want to get the most utilization for blowing.  With an EXAIR Super Air Knife, it has a 40:1 amplification ratio.; or, in other words, you can get 40 mpg.  If you use the EXAIR Standard or Full Flow Air Knife, you can get 30 mpg.  But, if you use drilled pipes, copper tubes, etc. for blowing, then you are only getting 5 to 10 mpg.  If you want to get the most “distance” from your compressed air system, you want to check the “gas mileage” of your blow-off components.

EXAIR can “tune up” your blow-off systems to make them efficient and safe by contacting an Application Engineer.  We will be happy to help you.

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

Return On Investment: Does It Matter, And How Much?

I have a friend who participates in a process known as “extreme couponing.” She has multiple subscriptions to the Sunday edition of our major newspaper, and a couple of local papers that also have coupon inserts. When I see her at the grocery store, she’s got two 4″ binders full of baseball card holders, all stuffed with multiples of clipped coupons, organized by store aisle. The insane amount of money saved is a big factor in her being able to be a stay-at-home mother, which is something else she’s pretty good at.

If you get stuck at step one…or even two…extreme couponing may not be for you!

Now, extreme couponing isn’t for everyone. Even beginners to the process can buy a year’s worth of paper towels for next to nothing. However, that may take up so much room in their house that they need to rent a storage facility for other belongings that folks like you and me simply keep in the garage or basement. It also takes a LOT of time and effort to do it right – as well as discipline. Saving half (or more) on a truckload of stuff you don’t need (or will never use) is a waste of money, time, and space. In fact, I know people who have abandoned extreme couponing for those very reasons…the “return on investment” just isn’t there.

That’s the deal in industry too.  Anyone tasked with finding and exploiting efficiencies – or finding and eliminating inefficiencies – is going to be looking at return on investment.  Like extreme couponing, though, it has to make sense in all aspects of the operation.  For example:

*An OEM taking advantage of a quantity discount for components or subassemblies has to not only have the storage space available, but also has to consider the turnover rate…it costs money to keep product on the shelf.

*A machine shop considering a tooling upgrade has to compare the cost difference with the increased performance and/or lifespan of the “new and improved” product.  A tool that costs 10% more but lasts twice as long is probably a good deal.  A tool that costs twice as much but lasts 10% longer might not provide the “bang for the buck.”

*Any facility, before switching a service or utility provider, will “run the numbers” on promotional rates, contract terms, etc. before making a commitment.

Unlike extreme couponing, EXAIR makes it easy – and beneficial – to evaluate the return on investment:

*Our catalog (if you don’t have the latest, get it here) has complete performance & operational data on all of our products.  This is great if you know what you want it to do.

*If you’re not quite sure, our catalog also has a good number of actual application write-ups for most of our Intelligent Compressed Air Products.  You may be able to find something that’s similar to what you want to do, and further inform your selection from there.

*Once you’ve chosen a product, you can use the Calculator Library on our website to determine actual dollar cost savings associated with replacing a current compressed air powered device with an EXAIR product.

*Application Engineers are available to discuss your application and/or product selection via phone, email, or Live Chat.

*No matter how detailed the discussion, and how confident a plan we may make, the age-old saying about how it “looked good on paper” proves itself every now and again.  When this happens, all catalog products are covered by our 30 Day Unconditional Guarantee.  If you’re not satisfied for any reason within 30 days of purchase, we’ll arrange return for full credit.

*Let’s assume that we’re pretty good at this (because we are) and it actually DOES work out (because it usually does) – we can calculate your new (and improved) operating costs and compare them with the cost of your previous devices.  If you don’t have the instrumentation (flow meters, sound level meters, etc.,) this is a free service we provide in our Efficiency Lab.  Send it in, and we’ll do a full performance test & issue a comprehensive report, all at no charge.  And if you qualify for a Case Study, we can even save you some money on your next order.  Contact me for more details if you’re interested.

Free testing. Verifiable data. EXAIR Efficiency Lab.

Russ Bowman
Application Engineer
EXAIR Corporation
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Coupon Pile Stock Photos courtesy of Carol Pyles  Creative Common License

Compressed Air Uses In Industry

Air Compressor

There are so many uses for compressed air in industry that it would be difficult to list every one of them as the list would be exhaustive.  Some of the uses are the tools used in production lines, assembly & robotic cells, painting, chemical processing, hospitals, construction, woodworking and aerospace.

It is considered as important as water, electricity, petroleum based fuels and often referred to as the fourth utility in industry. The great advantage of compressed air is the high ratio of power to weight or power to volume. In comparison to an electric motor compressed air powered equipment is smoother.  Also compressed air powered equipment generally requires less maintenance, is more reliable and economical than electric motor powered tools.  In addition they are considered on the whole as safer than electric powered devices.

Even amusement parks have used compressed air in some capacity in the operation of thrill rides like roller coasters or to enhance the “wow factor” of certain attractions. Compressed air can be found in your dentist’s office where it is used to operate drills and other equipment. You will find compressed air in the tires on your car, motorcycle and bicycles. Essentially, if you think about it, compressed air is being used nearly everywhere.

Here at EXAIR, we manufacture Intelligent Compressed Air Products to help improve the efficiency in a wide variety of industrial operations. Whether you are looking to coat a surface with an atomized mist of liquid, conserve compressed air use and energy, cool an electrical enclosure, convey parts or bulk material from one location to another or clean a conveyor belt or web, chances are we have a product that will fit your specific need.

Atomizing nozzle
Atomizing Nozzles Can Apply Even Coatings
Super Air Amplifier
Air Amplifiers pull in a large volume of ambient air to increase air flow volume and are great for cooling applications!
Heavy Duty Threaded Line Vac
For conveying heavy or abrasive products the Heavy Duty Threaded Line Vacs have male NPT Threads to make permanent and rigid installation into a piping system a breeze.

If you would like to discuss quiet, efficient compressed air products, I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Estimating the Total Cost of Compressed Air

It is important to know the cost of compressed air at your facility.  Most people think that compressed air is free, but it is most certainly not.  Because of the expense, compressed air is considered to be a fourth utility in manufacturing plants.  In this blog, I will show you how to calculate the cost to make compressed air.  Then you can use this information to determine the need for Intelligent Compressed Air® products.

There are two types of air compressors, positive displacement and dynamic.  The core construction for both is an electric motor that spins a shaft.  Positive displacement types use the energy from the motor and the shaft to change the volume in an area, like a piston in a reciprocating compressor or like rotors in a rotary compressor.  The dynamic types use the energy from the motor and the shaft to create a velocity energy with an impeller.  (You can read more about air compressors HERE).  For electric motors, the power is described either in kilowatts (KW) or horsepower (hp).  As a unit of conversion, there are 0.746 KW in 1 hp.  The electric companies charge at a rate of kilowatt-hour (KWh).  So, we can determine the energy cost to spin the electric motors.  If your air compressor has a unit of horsepower, or hp, you can use Equation 1:

Equation 1:

hp * 0.746 * hours * rate / (motor efficiency)

where:

hp – horsepower of motor

0.746 – conversion to KW

hours – running time

rate – cost for electricity, KWh

motor efficiency – average for an electric motor is 95%.

If the air compressor motor is rated in kilowatts, or KW, then the above equation can become a little simpler, as seen in Equation 2:

Equation 2:

KW * hours * rate / (motor efficiency)

where:

KW – Kilowatts of motor

hours – running time

rate – cost for electricity, KWh

motor efficiency – average for an electric motor is 95%.

As an example, a manufacturing plant operates 250 day a year with 8-hour shifts.  The cycle time for the air compressor is roughly 50% on and off.  To calculate the hours of running time, we have 250 days at 8 hours/day with a 50% duty cycle, or 250 * 8 * 0.50 = 1,000 hours of running per year.  The air compressor that they have is a 100 hp rotary screw.  The electrical rate for this facility is at $0.08/KWh. With these factors, the annual cost can be calculated by Equation 1:

100hp * 0.746 KW/hp * 1,000hr * $0.08/KWh / 0.95 = $6,282 per year.

In both equations, you can substitute your information to see what you actually pay to make compressed air each year at your facility.

The type of air compressor can help in the amount of compressed air that can be produced by the electric motor.  Generally, the production rate can be expressed in different ways, but I like to use cubic feet per minute per horsepower, or CFM/hp.

The positive displacement types have different values depending on how efficient the design.  For a single-acting piston type air compressor, the amount of air is between 3.1 to 3.3 CFM/hp.  So, if you have a 10 hp single-acting piston, you can produce between 31 to 33 CFM of compressed air.  For a 10 hp double-acting piston type, it can produce roughly 4.7 to 5.0 CFM/hp.  As you can see, the double-acting air compressor can produce more compressed air at the same horsepower.

The rotary screws are roughly 3.4 to 4.1 CFM/hp.  While the dynamic type of air compressor is roughly 3.7 – 4.7 CFM/hr.  If you know the type of air compressor that you have, you can calculate the amount of compressed air that you can produce per horsepower.  As an average, EXAIR uses 4 CFM/hp of air compressor when speaking with customers who would like to know the general output of their compressor.

With this information, we can estimate the total cost to make compressed air as shown in Equation 3:

Equation 3:

C = 1000 * Rate * 0.746 / (PR * 60)

where:

C – Cost of compressed air ($ per 1000 cubic feet)

1000 – Scalar

Rate – cost of electricity (KWh)

0.746 – conversion hp to KW

PR – Production Rate (CFM/hp)

60 – conversion from minutes to hour

So, if we look at the average of 4 CFM/hp and an average electrical rate of $0.08/KWh, we can use Equation 3 to determine the average cost to make 1000 cubic feet of air.

C = 1000 * $0.08/KWh * 0.746 / (4 CFM/hp * 60) = $0.25/1000ft3.

Once you have established a cost for compressed air, then you can determine which areas to start saving money.  One of the worst culprits for inefficient air use is open pipe blow-offs.  This would include cheap air guns, drilled holes in pipes, and tubes.  These are very inefficient for compressed air and can cost you a lot of money.  I will share a comparison to a 1/8” NPT pipe to an EXAIR Mini Super Air Nozzle.  (Reference below).  As you can see, by just adding the EXAIR nozzle to the end of the pipe, the company was able to save $1,872 per year.  That is some real savings.

Compressed Air Savings

Making compressed air is expensive, so why would you not use it as efficiently as you can. With the equations above, you can calculate how much you are paying.  You can use this information to make informed decisions and to find the “low hanging fruit” for cost savings.  As in the example above, targeting the blow-off systems in a facility is a fast and easy way to save money.  If you need any help to try and find a way to be more efficient with your compressed air system, please contact an Application Engineer at EXAIR.  We will be happy to assist you.

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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Heat Recovery from an Air Compressor

On the whole most of us are quite aware of the considerable savings that can be accomplished by wise use and recovery of energy.   One way that a plant can save substantially is to capture the energy that an electric motor adds to the compressed air from the air compressor.  As much as 80% to 93% of the electrical energy used by an industrial air compressor is converted to heat.  A properly designed heat recovery system can capture anywhere between 50% to 90% of this energy and convert it to useful energy.

The heat recovered is sufficient in most cases to use in supplemental ways such as heating water and space heating, however generally there is not enough energy to produce steam directly.

IngersollRand_R-series-R110
Ingersoll Rand Rotary Screw Compressor

 

Packaged air cooled rotary screw compressor lend themselves easily to heat recovery, supplemental heating or other hot air uses very well due to their enclosed design.  Since ambient air is directed across the compressors aftercooler and lubricant cooler where the heat can be easily collected from both the compressed air and the lubricant.

Packaged coolers are normally enclosed cabinets that feature integral heat exchangers and fans.  This type of system only needs ducting and an additional fan to minimize back pressure on the air compressors cooling fan.  This arrangement can be controlled with a simple thermostat operated vent on a hinge and when the extra heat is not required it can be ducted outside the facility.

The recovered energy can be used for space heating, industrial drying, preheating aspirated air for oil burners or  other applications requiring warm air.  Typically there is approximately 50,000 Btu/Hr of energy available from each 100 SCFM of capacity (at full load).  The temperature differential is somewhere between 30°F – 40°F above the air inlet temperature and the recovery efficiency is commonly found to be 80% – 90%.

We all know the old saying there is “no free lunch” and that principle applies here.  If the supply air is not from outside the plant a drop in the static pressure could occur in the compressor cabinet thereby reducing the efficiency of the compressor.  If you choose to use outside air for makeup, you might need some return air to keep the air above freezing to avoid compressor damage.

Heat recovery is generally not utilized with water cooled compressors since an extra stage of heat exchange is required and the efficiency of recovering that heat is normally in the 50% – 60% range.

To calculate annual energy savings:

Energy Savings (Btu/Yr) = 0.80 * compressor bhp * 2,545 Btu/bhp-hour * hours of operation.

If we consider a 50 HP compressor:

.080 * 50bhp * 2,545 Btu/bhp-hour * 2080 hrs/year =  211,744,000 Btu/yr

Where 0.80 is the recoverable heat as a percentage of the units output, 2,545 is the conversion factor.

Cost savings in dollars per year = [(energy savings in Btu/yr)/Btu/fuel) x ($/unit fuel)]/primary heater efficiency.

If you would like to discuss saving money by reducing compressed air demand and/or any EXAIR product,  I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Photo courtesy of CC BY 3.0, https://en.wikipedia.org/w/index.php?curid=32093890

 

 

Compressor Control – A Way to Match Supply to Demand

Rarely does the compressed air demand match the supply of the compressor system. To keep the generation costs down and the system efficiency as high as possible Compressor Controls are utilized to maximize the system performance, taking into account system dynamics and storage. I will touch on several methods briefly, and leave the reader to delve deeper into any type of interest.

air compressor

  • Start/Stop – Most basic control –  to turn the compressor motor on and off, in response to a pressure signal (for reciprocating and rotary type compressors)
  • Load/Unload – Keeps the motor turning continuously, but unloads the compressor when a pressure level is achieved.  When the pressure drops to a set level, the compressor reloads (for reciprocating, rotary screw, and centrifugal type)
  • Modulating – Restricts the air coming into the compressor, as a way to reduce the compressor output to a specified minimum, at which point the compressor is unloaded (for lubricant-injected rotary screw and centrifugal)
  • Dual/Auto Dual – Dual Control has the ability to select between Start/Stop and Load /Unload control modes.  Automatic Dual Control adds the feature of an over-run timer, so that the motor is stopped after a certain period of time without a demand.
  • Variable Displacement (Slide Valve, Spiral Valve or Turn Valve) – Allows for gradual reduction of the compressor displacement while keeping the inlet pressure constant (for rotary screw)
  • Variable Displacement (Step Control Valves or Poppet Valves) – Similar effect as above, but instead of a gradual reduction, the change is step like (for lubricant injected rotary types)
  • Variable Speed – Use of a variable frequency AC drive or by switched reluctance DC drive to vary the speed of the motor turning the compressor. The speed at which the motor turns effects the output of the system.

In summary – the primary functions of the Compressor Controls are to match supply to demand, save energy, and protect the compressor (from overheating, over-pressure situations, and excessive amperage draw.) Other functions include safety (protecting the plant and personnel), and provide diagnostic information, related to maintenance and operation warnings.

If you would like to talk about compressed air or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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