## Opportunities to Save On Compressed Air

To start, what is an air compressor and why does it cost so much in electricity?  There are two types of air compressors, positive displacement and dynamic.  The core components for these air compressors is an electric motor that spins a shaft.  Like with many mechanical devices, there are different efficiencies.  Typically, an air compressor can put out anywhere from 3 SCFM per horsepower to 5 SCFM per horsepower.  (EXAIR settles on 4 SCFM/hp as an average for cost calculations.)  Equation 1 shows you how to calculate the cost to run your air compressor.

Equation 1:

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

where:

Cost – US\$

hp – horsepower of motor

0.746 – conversion KW/hp

hours – running time

rate – cost for electricity, US\$/KWh

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

As an example, a manufacturing plant operates a 100 HP air compressor in their facility.  The cycle time for the air compressor is roughly 60%.  To calculate the hours of running time per year, I used 250 days/year at 16 hours/day.  So operating hours equal 250 * 16 * 0.60 = 2,400 hours per year.  The electrical rate for this facility is \$0.08/KWh. With these factors, the annual cost to run the air compressor can be calculated by Equation 1:

Cost = 100hp * 0.746 KW/hp * 2,400hr * \$0.08/KWh / 0.95 = \$15,077 per year in just electrical costs.

There are two major things that will rob compressed air from your system and cost you much money.  The first is leaks in the distribution system, and the second is inefficient blow-off devices.   To address leaks, EXAIR offers an Ultrasonic Leak Detector.  The Ultrasonic Leak Detector can find hidden leaks to fix. That quiet little hissing sound from the pipe lines is costing your company.

A University did a study to find the percentage of air leaks in a typical manufacturing plant.  For a poorly maintained system, they found on average that 30% of the compressor capacity is lost through air leaks.  Majority of companies do not have a leak preventative program; so, majority of the companies fall under the “poorly maintained system”.  To put a dollar value on it, a leak that you cannot physically hear can cost you as much as \$130/year.  That is just for one inaudible leak in hundreds of feet of compressed air lines.  Or if we take the University study, the manufacturing plant above is wasting \$15,077 * 30% = \$4,523 per year.

The other area to check is air consumption.  A simple place to check is your blow-off stations.  Here we can decide how wasteful they can be.  With values of 4 SCFM/hp and an electrical rate of \$0.08/KWh (refence figures above), the cost to make compressed air is \$0.25 per 1000 ft3 of air.

One of the worst culprits for inefficient air usage is open pipe blow-offs.  This would also include cheap air guns, drilled holes in pipes, and tubes.  These devices are very inefficient for compressed air usage and can cost you a lot of money.  As a comparison, a 1/8” NPT pipe versus an EXAIR Mini Super Air Nozzle.  (Reference below).  As you can see, by just adding the EXAIR nozzle to the end of one pipe, the company was able to save \$1,872 per year.  That is some real savings.

By following the Six Steps to optimize your compressed air system, you can cut your energy consumption, improve pneumatic efficiencies, and save yourself money.  With the added information above, you can focus on the big contributors of waste.  If you would like to find more opportunities to save compressed air, you can contact an Application Engineer at EXAIR.  We will be happy to help.

John Ball
Application Engineer
Email: johnball@exair.com

## One Air Nozzle Saves \$960 per Year – How Many Nozzles Could You Use?

A cardboard manufacturing facility was using a 3/8” outside diameter (OD) open tube to blow scrap cardboard off a conveyor. This scrap cardboard would occasionally be blown inside the roller area at the end of a conveyor creating a maintenance nightmare that required hours to disassemble and remove. To prevent this from occurring they installed another 3/8″ OD open compressed air tube to divert any cardboard headed toward the conveyor roller. The 3/8″ open tubing eliminated the scrap problem, but introduced a few new ones. The open hose is extremely noisy over (100 dBA). It does not comply with OSHA standard CFR 1910.242(b), which requires that a compressed air blow off device may not be dead ended at more than 30 PSIG. The most costly problem though is a 3/8″ open tubing uses a tremendous amount of compressed air.

They were using so much air in the facility that they were draining the system pressure in their facility. Obviously, they were going to replace the open tube with EXAIR 2” Flat Super Air Nozzle. Replacing this open blow off with an intelligent compressed air product, like the HP1125 High Powered Flat Super Air Nozzle or the 1104 Super Air Nozzle, would lower the noise level below 83 dBA. Also, those nozzles use significantly less air. They decided to use the model HP1125 for its thin profile to fit into the tight location. The only question was how much air and energy cost would they save. They could have easily installed a Digital Flow Meter on the supply pipe of the open tube to measure the change in flow once the EXAIR nozzle had been installed, but they wanted to try and estimate the air usage.

Using EXAIR’s test data, we know a 3/8″ OD open tube that is 18″ long will flow 68.5 SCFM at 80 PSIG. An HP1125 2″ Flat Super Air Nozzle utilizes 37 SCFM when fed with 80 PSIG inlet pressure. By removing one 3/8″ OD tube the cardboard manufacturer saved 31.5 SCFM of compressed air. With an electrical cost of \$0.08 per kWh, compressed air costs \$0.25 per 1000 SCF. Saving 31.5 SCFM reduces the manufacturers electrical bill by \$0.48 every hour, \$3.48 for every 8 hour shift, and \$960 per year (250 working days, eight hours a day). If the manufacturer runs two shifts, the savings will double. The simple return on investment for this nozzle is 130 hours! How many projects can you measure a return on investment in hours?

Take advantage of our free service – the EXAIR Efficiency Lab. Our Application Engineers will test any nozzle or device you choose to send in to the Lab using our calibrated testing equipment. We’ll compare the performance of your existing product (air consumption, noise, force, etc.) with an EXAIR Intelligent Compressed Air product. The results will be published in a comprehensive report, including a cost savings analysis with simple ROI. For most applications, EXAIR products can help you improve compressed air efficiency AND pay for themselves in a matter of weeks!

EXAIR intelligent compressed air products are easy to install, safe, and efficient. By installing these products instead of using unsafe open blow offs, your company can save thousands of dollar every year with minimal investment. While saving electrical expenses, we decrease the noise level which makes your production force a nicer place to work. We also comply with OSHA’s standards. Finally, we may be able to design the blow off better to consistently produce the quality product you expect. Call EXAIR today to discuss your application.

Dave Woerner
Design Engineer at EXAIR Corporation
DaveWoerner@EXAIR.com