VFD or not, it might make sense to add a ~5HP disposable/cheapo compressor to keep up with leakage and occasional use so you don't pay for starting a 200HP motor just to top up a bicycle tire.

Mike Halloran
Pembroke Pines, FL, USA

My experience in this area is 10+ years old. BOTH are strong companies, but I chose Ingersoll. I think my decision process was based on (1) product features and (2) their support organization: location service centers, locations of parts warehouses, relationship with their Applications Engineering guys who helped educate me of how to effectively manage my consumption of that outrageously expensive commodity called "compressed air."

My experiences:
Retrofitted compressors at one plant. Two compressors (a newer Low Vol/High Pressure unit and an ancient High Vol/Low Pressure unit) were both being used by the Maintenance Department for some reason to supply plant capacity. Our plant needs were LP/HV. IR performed a paid analysis and determined the LV/HP compressor was running constantly but not contributing to the plant consumption load. I retrofitted the LV/HP to a HV/LP screw, used it for primary since it was newer vintage, turned off the older HV/LP and kept it for backup. I found a Dept of Energy website that gave me the formula for compressor run time = $$ of electrical energy cost, and showed The Boss that the act of turning the unit off saved the company about $80K per year.

The other was a new installation for a 2nd plant, I went with the VFD drive. I had the luxury of specifying distribution piping and accumulator tanks to give me good load & supply balance all over the facility. IR Engineers helped me with that.

After all of that, we started a campaign of reducing our compressed air consumption:

• Eliminated all leaks & hissing noises. Told by multiple sources that anytime one hears leaking compressed air, it should be assigned a cost of $0.25 to $5 per minute of electricity. Compressed air is precious and expensive: don't waste it.
• Eliminated the use of open line pressure usage like using full line pressure (90 psi) as a floor sweeping tool. Besides the safety issue, this is a terrible waste. All blow offs were set at 30 psi unless special variance was granted.
• All pneumatic power uses were configured for 60 psi max unless given variance. Air tools, cylinders, etc.
• Training & education of workers and staff as to why this was being done.
• Started looking for opportunities to reconfigure distribution piping & adding accumulator tanks for better load balance.

It took a while, but compressed air consumption finally got under control, reduced costs, & manageable.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com