Precise air-pressure control is required to test hydraulic components machined at The Lee Company."Our decisions to buy new air compressors have been based on energy efficiency and operating costs savings, as well as the need to provide sufficient capacity to meet expanding production requirements," Rabideau says. The company's first variable-speed-drive (VSD) compressor replaced three older constant-speed modulating screw machines at its Industrial Micro-Hydraulics Group plant. This plant operates 24/7 making check valves for antilock braking systems."In the past, we had to overpressurize the system receiver and route the air through a pressure-regulating valve to provide the 117 psi that our test equipment requires," Rabideau says. Although two of the three older compressors have load/no-load control capability, the narrow pressure range virtually ensured that all three compressors ran continuously, even under part-load conditions."Now we can use the variable-speed drives to provide the exact pressures we need," Rabideau says. "The savings in energy and operating costs, coupled with the power company's energy efficiency incentive payment, resulted in a simple payback of just over a year on this VSD installation."During the past two-and-a-half years, the company has purchased five Atlas Copco compressors for four of its seven Connecticut plants. One is an oil-free constant-speed compressor, another is a constant-speed lubricated compressor, and the other three are VSD lubricated compressors.The new oil-free machine at the company's Electro Fluidic Division plant replaced four oil-free reciprocating compressors that had become a maintenance "nightmare." Among the company's most recent compressor purchases were the constant-speed lubricated screw compressor coupled with a VSD unit for its new 90,000-sq.-ft. Restrictor Group plant."The GA VSD compressors are very energy efficient," Rabideau says. They reduce energy consumption by completely eliminating unloaded power consumption, saving up to 22% on the total life-cycle cost. He adds, "The reason we selected the later versions of the Atlas Copco VSD machines is we had such good success with the first GA50 VSD machine we purchased."