Don’t Forget About Operating Cost: How To Calculate Return On Investment

If you have a stock portfolio, or even a retirement account, you’ve likely heard the term “return on investment.” It basically tells you how hard your money is working for you, and, the higher, the better.

The term is also used to determine the financial benefits associated with the use of more efficient products than you’re using right now:

  • The cost of operating industrial pumps, air compressors, and a variety of industrial rotating equipment, can be greatly reduced by using variable frequency drive systems that sense the demand and change the motor’s speed (and hence power consumption) accordingly.  These systems are not cheap, but the reduction in operating costs is often quite noticeable.
  • At home, installing energy efficient windows (spoiler alert: your builder probably used the cheapest ones he could find…mine sure did) or upgrading appliances & HVAC can cost a pretty penny, but you’ll also see your electric bill go down.

EXAIR Corporation has a worldwide reputation for providing highly efficient compressed air products for industry.  Our Engineering Department has a company-wide reputation for being data fanatics…which is key to allowing us to provide our customers with ample information to make the best choices to optimize your use of your compressed air.

It’s not hard at all to calculate your potential savings from the use of an engineered compressed air product, assuming you know how much air your current device is using.  If not, we can tell you if you can send it in for Efficiency Lab testing (free and fast; call me to find out more.)  Here’s an example for a VERY typical situation: replacing an open copper tube blow off with an EXAIR Super Air Nozzle:

  • A 1/4″ copper tube uses 33 SCFM @80psig
  • A Model 1100 Super Air Nozzle uses 14 SCFM @80psig

33 SCFM X 60 min/hour X 8 hours/day X 5 days/week X 52 weeks/year = 4,118,400 SCF

14 SCFM X 60 min/hour X 8 hours/day X 5 days/week X 52 weeks/year = 1,747,200 SCF

4,118,400 – 1,747,200 = 2,371,200 Standard Cubic Feet of compressed air savings

If you know your facility’s cost of compressed air generation, you can calculate the monetary savings.  If not, we can get a good estimate via a thumbrule used by the U.S. Department of Energy that says it typically costs $0.25 to generate 1,000 SCF of compressed air:

2,371,200 SCF X $0.25 ÷ 1,000 SCF = $592.80 annual monetary savings

In 2019, the cost of a Model 1100 Zinc Aluminum Super Air Nozzle is $41.00.  Daily savings (not counting weekends) is:

$592.80 ÷ 260 days (5 days/week X 52 weeks/year) = $2.28 daily savings

Meaning the payoff time for the $41.00 investment in the Model 1100 is:

$41.00 ÷ $2.28 = 17.9 days

Or…just over three weeks.  Now that I’ve shown you the math, I’d like to introduce you to the EXAIR Cost Savings Calculator.  Just enter the data, and it’ll check your math (because I know you’re going to do the math anyway, just like I would.)  It even does the ROI for you too.

Engineered solutions (like EXAIR Intelligent Compressed Air Products) are the efficient, quiet, and safe choice. Does the one on the right look familiar?  It’s literally the example I used for the above calculations.

If you’d like to find out more about how – and how fast – EXAIR Intelligent Compressed Air Products can pay off for you, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Video Blog: How To Calculate Air Consumption At A Pressure Other Than Published Values

The below video shows how to calculate the air consumption when operating at any pressure.

If you want to discuss efficient compressed air use or any of EXAIR’s engineered compressed air products, give us a call or email.  We would enjoy hearing from you!

Steve Harrison
Application Engineer
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How to Calculate SCFM (Volume) When Operating at Any Pressure

If you need to operate at a different pressure because you require less or more force or simply operate at a different line pressure, this formula will allow you to determine the volume of air being consumed by any device.

Volume Formula

Using the EXAIR 1100 Super Air Nozzle as our example:

1100

Lets first consider the volume of the 1100 Super Air Nozzle at a higher than published pressure.  As shown in the formula and calculations it is simply the ratio of gauge pressure + atmospheric divided by the published pressure + atmospheric and then multiply the dividend by the published volume.  So as we do the math we solve for 17.69 SCFM @ 105 PSIG from a device that was  shown consume 14 SCFM @ 80 PSIG.

higher

Now lets consider the volume at a lower than published pressure.  As shown it is simply the ratio of gauge pressure + atmospheric divided by the published pressure + atmospheric and then multiply the dividend by the published volume.  So as we do the math we solve for 11.04 SCFM @ 60 PSIG from a device that was shown to consume 14 SCFM @ 80 PSIG.

lower

When you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call.  Experience the EXAIR difference first hand and receive the great customer service, products and attention you deserve!  We would enjoy hearing from you.

Steve Harrison
Application Engineer
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Consider these Variables When Choosing Compressed Air Pipe Size

Here on the EXAIR blog we discuss pressure drops, correct plumbing, pipe sizing, and friction losses within your piping system from time to time.   We will generally even give recommendations on what size piping to use.  These are the variables that you will want to consider when selecting a piping size that will suit your need and give the ability to expand if needed.

The variables to know for a new piping run are as follows.

  • Flow Rate (SCFM) of demand side (products needing the supplied compressed air)
  • System Pressure (psig) – Safe operating pressure that will account for pressure drops.
  • Minimum Operating Pressure Allowed (psig) – Lowest pressure permitted by any demand side point of use product.
  • Total Length of Piping System (feet)
  • Piping Cost ($)
  • Installation Cost ($)
  • Operational Hours ( hr.)
  • Electical Costs ($/kwh)
  • Project Life (years) – Is there a planned expansion?

An equation can be used to calculate the diameter of pipe required for a known flow rate and allowable pressure drop.   The equation is shown below.

A = (144 x Q x Pa) / (V x 60 x (Pd + Pa)
Where:
A = Cross-Sectional are of the pipe bore. (sq. in.).
Q = Flow rate (cubic ft. / min of free air)
Pa = Prevailing atmospheric absolute pressure (psia)
Pd  = Compressor discharge gauge pressure (psig)
V = Design pipe velocity ( ft/sec)

If all of these variables are not known, there are also reference charts which will eliminate the variables needed to total flow rate required for the system, as well as the total length of the piping. The chart shown below was taken from EXAIR’s Knowledge Base.

Piping
Airflow Through 1/4″ Shed. 40 Pipe

Once the piping size is selected to meet the needs of the system the future potential of expansion should be taken into account and anticipated for.   If no expansion is planned, simply take your length of pipe and start looking at your cost per foot and installation costs.    If expansions are planned and known, consider supplying the equipment now and accounting for it if the additional capital expenditure is acceptable at this point.

The benefits to having properly sized compressed air lines for the entire facility and for the long term expansion goals makes life easier.   When production is increased, or when new machinery is added there is not a need to re-engineer the entire system in order to get enough capacity to that last machine.   If the main compressed air system is undersized then optimal performance for the facility will never be achieved.   By not taking the above variables into consideration or just using what is cheapest is simply setting the system up for failure and inefficiencies.   All of these considerations lead to an optimized compressed air system which leads to a sustainable utility.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF