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

 

Celebrate Earth Day 2018!

Earth Day is one of those days not everyone is aware happens, even with all of the news and notable facts about our resources and pollution. EXAIR is committed to raising awareness of Earth Day and encourages everyone to find an activity which produces action in the spirit of Earth Day. For example, could you help clean up a riverbank in your town, or plant some trees in a park, or recycle your household plastic/glass/aluminum/cardboard? The Earth Day website has a bunch of great suggestions for you to make a difference.

Volunteers help cleanup

At my home, we recycle our glass, metal, plastic and cardboard. At EXAIR we continue to make progress in reducing our overall footprint as well.

Sunday, April 22nd marks the 48th annual Earth Day and it will be observed in 192 countries. For EXAIR, this year marks our 35th year helping compressed air users save compressed air energy and electrical resources. It is also another year that we continue to focus on manufacturing our products with minimal impact and doing our part to help protect our planet. We are proud to manufacture efficient products, implement processes and programs throughout our facility to help use our resources wisely and recycle everything we possibly can.

First and foremost, we manufacture and sell Intelligent Compressed Air Products that are specifically designed to reduce the use of compressed air throughout facilities. On top of that, when you purchase an EXAIR product it will arrive in fully recyclable packaging and, in most cases, is made from a material that will be recyclable should it reach a point it is no longer useful.

In the past year we have improved the efficiency of our computers and computer servers which require fewer Kilowatt hours (KWH) per day . We have been able to reduce KWH/day by over 56%! This reduces our impact on the local electricity provider and further shrinks our impact upon precious resources.

EXAIR recycles 100% of the metal scrap from our machining processes, which equates to 6.5 tons. Our cardboard and mixed paper products are also recycled 100%. Of the waste we place into our trash dumpsters – 80% is recycled and 20% is sent to the landfill. The paper products even get down to all of paper towels that are used and all the scratch paper that the office utilizes. In total, EXAIR recycled 35.4 tons of paper and cardboard in 2017. We focus on more ways to improve this percentage every year.

Another waste reducing factor that has proven to work out well for EXAIR is asking every customer if they accept digital invoices rather than requiring them to be printed and mailed. Thanks to our wonderful customers we have been able to eliminate 91% of all printed and mailed invoices which helps to reduce our resources used as well as the amount of materials that are possibly turned into solid wastes at their facilities. This also prevents the gas and vehicles necessary to deliver all of these invoices by mail.

To get back to what EXAIR products have done to help reduce waste, we were also able to optimize our own compressed air system by eliminating air leaks and have saved 1 million cubic feet of compressed air. We have also utilized our very own Chip Trapper Systems in our manufacturing areas and extended the water soluble coolant life from 6 weeks per changeover to 6 months per changeover. Keeping our coolant clean allows us to minimize the total amount of wastewater we recycle each year.

We continued to reduce our wastewater for reclamation – in 2017 we recycled 795 gallons, a reduction of 213 gallons compared to 2016, due to extending the life of our coolant.

On top of all the efforts above, we also continue to maintain RoHS compliance on all electronic products, as well as actively track our supply chains to ensure no Conflict Minerals are being sourced from the Democratic Republic of Congo.

If you have any questions on how we can help your facility reduce their use of compressed air or why we continue to reduce our wastes and increase our recycling efforts, contact us.

To see our full Sustainability Plan follow this link.

Enjoy Your Weekend,
EXAIR Corporation

 

Thank you to Kate Ter Haar for the Happy Earth Day image. Creative Commons License.
Thank you to AFS-USA Intercultural Programs for the volunteer image. Creative Commons License. 

More Efficient Compressed Air Use Could Lead To Energy Rebates

The use of compressed air can be found in almost any industry and is often referred to as a “fourth utility” next to water, gas and electric. The generation of compressed air accounts for approximately 1/3 of all energy costs in an industrial facility, in many cases, it’s the largest energy user in an industrial plant. With an average cost of $ 0.25 per every 1,000 SCF used, compressed air can be expensive to produce so it is very important to use this utility as efficiently as possible.

Utility companies recognize the benefit of using engineered products to reduce compressed air usage, like the ones manufactured by EXAIR, and offers rebate incentives for making a switch. Our local utility provider here in Cincinnati, Duke Energy, offers a $ 20 incentive for each replacement engineered nozzle.

 

Our Model # 1100SS 1/4″ FNPT and Model # 1101SS 1/4″ MNPT Super Air Nozzles

In their specification, the nozzle must meet a certain volumetric flow rate (SCFM) at 80 PSIG operating pressure for a given pipe size. For example, when looking at a 1/4″ nozzle, the flow rate must be less than or equal to 17 SCFM when operated at 80 PSIG. Our most popular nozzles for “general” blowoff applications would be our Model # 1100 (1/4″ FNPT) or our Model # 1101 (1/4″ MNPT) Super Air Nozzles. These nozzles require 14 SCFM @ 80 PSIG so this would be the ideal solution to reduce the air demand and take advantage of the rebate.

Here at EXAIR, much of our focus is to improve the overall efficiency of industrial compressed air operating processes and point of use compressed air operated products. If you’d like to contact one of our application engineers, we can help recommend the proper engineered solution to not only save on your compressed air usage but also assist with possible energy rebates available in your area.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

FREE EXAIR Webinar – November 2nd, 2017 @ 2:00 PM EDT

On November 2, 2017 at 2 PM EDT, EXAIR Corporation will be hosting a FREE webinar titled “Optimizing Your Compressed Air System In 6 Simple Steps”.

During this short presentation, we will explain the average cost of compressed air and why it’s important to evaluate the current system. Compressed air can be expensive to produce and in many cases the compressor is the largest energy user in a plant, accounting for up to 1/3 of the total energy operating costs. In industrial settings, compressed air is often referred to as a “fourth utility” next to water, gas and electric.

Next we will show how artificial demand, through operating pressure and leaks, can account for roughly 30% of the air being lost in a system, negatively affecting a company’s bottom line. We will provide examples on how to estimate the amount of leakage in a system and ways to track the demand from point-of-use devices, to help identify areas where improvements can be made.

To close, we will demonstrate how following six simple steps can save you money by reducing compressed air use, increasing safety and making your process more efficient.

CLICK HERE TO REGISTER

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Video Blog: The Monetary Benefits of an Engineered Solution

This video highlights the value and benefits of an engineered blow off solution.  We take a homemade open pipe blowoff and replace it with an EXAIR model 1100 Super Air Nozzle.  This air nozzle is then controlled through our Electronic Flow Controller, allowing for intermittent On/Off of the compressed air flow.  And, these solutions are wirelessly monitored via Zigbee network using our Wireless Digital Flowmeter.  Implementing these solutions results in a compressed air reduction of over 90%!!!

 

Full calculations along with supporting flow values (pulled from the same data shown in the video above) are shown below.

Screengrab of the flow values shown in the video above. Click for larger image.

The open pipe:

The first compressed air flow values to show up on the EXAIR Logger are for the open pipe blow off.  At 1 BAR operating pressure, this “solution” consumes 22.3 SCFM of compressed air.  At a cost of $0.25 for every 1,000 cubic feet of compressed air, this nozzle will cost $695.76 to operate 8 hours per day, 5 days per week, 52 weeks per year.

The engineered EXAIR Super Air Nozzle

Model 1100 EXAIR Super Air Nozzles consumes 4.7 SCFM at an operating pressure of 1 BAR – a reduction of 79% compared to the open pipe.  These savings prove out in terms of operating cost as well – $146.64 per year, compared to $695.76.

The engineered EXAIR Super Air Nozzle with Electronic Flow Control (EFC)

By controlling the “ON” time for this application with an EFC, we are only blowing for 32% of the time for each minute of operation which changes the required compressed air flow from 4.7 SCFM to a peak value of 1.5 SCFM. This control saves an additional 68% of compressed air flow.  And, these savings are compounded by eliminating the need for constant compressed air flow.  Total annual operating cost for the EXAIR 1100 Super Air Nozzle with Electronic Flow Control is just $46.80.

Implementing an engineered solution can have a TREMENDOUS impact on energy costs and operating costs in your facility.  Compressed air is the most expensive utility to produce and consume, making the impact of proper solutions of high value to any business.  Let us help you utilize engineered compressed air solutions in your facility by contacting an EXAIR Application Engineer today.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

ROI – Return on Investment

Return on Investment (ROI) is a measure of the gain (preferably) or loss generated relative to the amount of money that was invested.  ROI is typically expressed as a percentage and is generally used for personal financial decisions, examining the profitability of a company, or comparing different investments.  It can also be used to evaluate a project or process improvement to decide whether spending money on a project makes sense.  The formula is shown below-

ROI

  • A negative ROI says the project would result in an overall loss of money
  • An ROI at zero is neither a loss or gain scenario
  • A positive ROI is a beneficial result, and the larger the value the greater the gain

Gain from investment could include many factors, such as energy savings, reduced scrap savings, cost per part due to increased throughput savings, and many more.  It is important to analyze the full impact and to truly understand all of the savings that can be realized.

Cost of investment also could have many factors, including the capital cost, installation costs, downtime cost for installation, and others.  The same care should be taken to fully capture the cost of the investment.

Example – installing a Super Air Nozzles (14 SCFM compressed air consumption) in place of 1/4″ open pipe (33 SCFM of air consumption consumption) .  Using the Cost Savings Calculator on the EXAIR website, model 1100 nozzle will save $1,710 in energy costs. The model 1100 nozzle costs $37, assuming a $5 compression fitting and $50 in labor to install, the result is a Cost of Investment of $92.00. The ROI calculation for Year 1 is-

ROI2

ROI = 1,759% – a very large and positive value.  Payback time is only 13 working days.

Armed with the knowledge of a high ROI, it should be easier to get projects approved and funded.  Not proceeding with the project costs more than implementing it.

If you have questions regarding ROI and need help in determining the gain and cost from invest values for a project that includes an EXAIR Intelligent Compressed Air® Product, 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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Twitter: @EXAIR_BB

A Digital Flowmeter can Help Improve Your Monthly Electric Bill

No one likes paying their bills at the end of the month.  But, if you can save yourself some money, it helps to make it a little easier.  For this customer, he received a monthly bill for his compressed air.

Monthly Bill

An industrial facility consisting of four separate manufacturing plants and a power company that supplied all of them with utilities, i.e. hot water, natural gas, electricity, and compressed air.  The parent company decided to reorganize and sell the entities.  At the end of it, the power company was controlled by a different organization than the manufacturing plants.  The power plant was contracted to still supply the utilities to the individual plants, but now they would be charged individually on a monthly basis.

Being that compressed air is one of the most expensive utilities, the general manager of a solid-state electronic plant really noticed the charge on his bill.  He did an estimate on the amount of air that his equipment was using, and he compared it to the charges.  There was roughly a 20% difference in the figures.  Because of the excessive amount of money, he contacted EXAIR to see what we could offer.

In discussing their system, the compressed air was supplied through one 6” schedule 40 black pipe.  The pipe came into the facility in the ceiling and it branched off to supply the entire shop with compressed air.  He was looking for something to measure the compressed air flow with the ability to measure a cumulative amount.  He could use this amount to compare to his monthly usage.  He was also concerned about cutting into his compressed air line as this could cause him much downtime and additional costs.  He needed something easy to install, accurate, and versatile.

EXAIR Digital Flowmeter

I suggested our 6” Digital Flowmeter with the Model 9150 Summing Remote Display.  EXAIR Digital Flowmeters are designed to measure flow continuously and accurately.  You do not need to weld, cut, or disassemble pipe lines to install.  With a drill guide, the Digital Flowmeter can be easily mounted onto the 6” black pipe by drilling two small holes.  After that, they just had to insert the Digital Flowmeter into the holes, and tighten the clamp around the pipe.  The total procedure took less than 30 minutes, so downtime was minimal.  The EXAIR Digital Flowmeter measures flow by comparative analysis with thermal dispersion; so, the accuracy is very high and recalibration is not required.

EXAIR Summing Remote

With the option of the Summing Remote Display, they could attach it to the Digital Flowmeter and display the flow remotely up to 50 feet away.  They mounted it on the wall next to his office for the operational functions.  With a simple press of a button, it can show the current flow rates, daily flow rates, and cumulative flow rates.  So, during the billing cycle, he was able to get the cumulative measurement to compare the results, and reset the counter to zero for the next month.

Believe it or not, the power company was correct in their measurements.  But, not to waste an entire blog, I did have him turn the compressed air supply off after business hours to watch the flow rate.  He did find his 20% difference in compressed air leakage.  The Digital Flowmeter was able to measure low flows to target other problem areas in your compressed air system.  Now he had another chore in leak detecting and pipe fixing.

EXAIR Optimization line has different products that can help you to get the most out of your compressed air system.  With the customer above, he was able to measure his compressed air flow with the Digital Flowmeter, as well as detecting other issues.  I will now have to talk to him about our Ultrasonic Leak Detector.

 

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb

 

Picture: Calculator Calculation Insurance by stevepb.  Creative Commons CC0 Public Domain