SUMMARY Cover of Hydraulics & Pneumatics magazine shows Suppressor installed on IMP pump.     To get a handle on the magnitude of the noise reduction at Eagle Precision, Sabine points out that a conventional 40-hp power unit mounted on the machine structure generated about 88 to 92 dBA of noise 3 ft from the source. Now, with a 60-hp IMP running at the same pressure and flow as the conventional power unit, noise has dropped to 78 to 80 dBA. "We attribute most of this to the IMP However, we mount the IMP differently than we did a conventional power unit. We also installed a pulsation dampener and put a 90° hose-and-tubing assembly at the pump outlet line. While these practices have some effect, the end result is a 10-dB reduction in noise, which makes a huge difference." To illustrate, Sabine mentioned that after adopting these techniques for their machines, the hydraulic power unit no longer is the greatest source of noise. "Our return line filtration is accomplished in a kidney loop tapped into the reservoir. A circulating pump routes fluid from the reservoir into a filter, through a heat exchanger, and back into the reservoir. Interestingly, the motor on the kidney loop's circulating pump makes more noise than the power unit. A conventional power unit makes so much noise that you can't even hear the circulating pump. On machines using the IMP, we might even start looking for quieter circulating pumps." Quiet operation sells "Any of these machines is basically a horizontal press," continues Sabine, "so we must ward off competition by continually developing ways of improving our products and services. We believe we have an edge over the competition right now with the quiet package we offer." Overbeeke adds, "Our quiet package using the IMP is less expensive and more effective than an equivalent package from our competitors. "Quieter operation of machines has become an issue not on North America, but especially in Europe, where our machines are manufactured and marketed through our facility in England. The health and safety requirements over there seem to be more stringent than in North America. Even so, many customers are beginning to incorporate specifications for noise as a basic application requirement."