There’s an old saying that goes “If it isn’t broken, don’t fix it.” Best case, this means it may not be necessary to repair, refurbish, or replace something just because there’s a newer offering on the market. Worst case, it’s used to justify continued use of something when the aforementioned repair, refurbishment, or replacement will result in quantifiable benefits. THAT makes THIS quote all the more applicable:
“The most dangerous phrase in the English language is: We’ve always done it this way. It raises the question, ‘Are we doing this because we always have, or because it’s the right thing to do?’”
-Grace Hopper, Rear Admiral USN & computer pioneer
If you consider “not spending any more than you have to on compressed air” to be “the right thing to do”, then this blog’s for you. Read on, and we’ll calculate not only how much you might save by using engineered compressed air products in place of what you’re using now, but how soon that amount you save will equal how much you spent on those products…that’s called Return On Investment, or ROI. Let’s work through an example:
A popular air gun fitted with a cross-drilled nozzle for OSHA compliance uses 34 SCFM @80psig. These are commonly replaced by our Model 1210 Soft Grip Safety Air Guns fitted with our Super Air Nozzles, which consume only 14 SCFM @80psig. It’s not likely that the trigger on an Air Gun used for blowing, cleaning, drying, etc., will be pulled continuously, but we can assume that two hours of “trigger time” per day (for an eight-hour shift) is reasonable. Here’s how to calculate annual savings:
(34-14 SCFM) X 60 min/hr X 2 hrs/day X 5 days/wk X 50 wks/yr=600,000 Standard Cubic Feet saved
Now, we need to determine the cost of your compressed air. The calculation for that, per the U.S. Department of Energy, is as follows:
Cost ($) = {bhp X 0.746 X # of operating hours X $/kWh X % time X % full load bhp}/motor efficiency
Where:
bhp = motor full load horsepower
0.746 = conversion from hp to kW
% time = percentage of run time at this operating level
% full load bhp = brake horsepower as percentage of full load bhp at this operating level
Motor efficiency = motor efficiency at this operating level
For simplicity, you could also get a fairly accurate answer by applying an “industry standard” thumb rule which states that a typical industrial air compressor generates ~4 SCFM per HP. If you know your electricity cost ($/kWh), you can calculate the cost of compressed air generation as follows. To keep most of the digits to the left of the decimal point, it’s commonly calculated as $ per 1,000 Standard Cubic Feet:
$/kWh X 0.746 hp/kW ÷ 4 hp/SCFM ÷ 60 min/hr X 1,000 = $ per 1,000 SCF
For EXTRA simplicity, you can use ANOTHER thumb rule, also endorsed by the Department of Energy, which states that compressed air costs about $0.25 per 1,000 SCF. It uses the above formula, and a typical estimate for electricity cost of $0.08 per kWh which my buddy Brian Farno did the math and provided a detailed explanation on that one here. So:
600,000 SCF X $0.25/1,000 SCF = $150.00 saved by switching to the EXAIR Safety Air Gun
Given the cost (current 2023 List Price) of $115.00 for the Model 1210 Soft Grip Safety Air Gun, we can calculate Return On Investment as a function of time…how long it takes before you end up saving the amount you spent:
$115.00 saved ÷ $150.00 spent X 12 months in a year = 9.2 months
At EXAIR (if you hadn’t figured it out already), we LOVE to do the math, but if you don’t (no judgment), we’ve got calculators on our website for that. Just fill in a few blanks, and get your answer. If there’s anything I can help with, though, give me a call.
Russ Bowman, CCASS
Application Engineer
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