When companies finally decide to make their manufacturing plants more energy efficient, the first targets for cost cutting tend to be their electric motors. Compressed air systems are rarely on their radar, which is amazing considering they represent about 10% of the energy a plant consumes. In the United States, compressed air systems account for $1.5 billion per year in energy costs. There are a variety of strategies to improve compressed air savings:
Oversizing valves wastes energy and takes up valuable space in machine and system designs. Using valves with solenoid air pilot and low watt coil designs also can reduce electrical costs. Using straight fittings, rather than 45° or 90° elbow fittings, wherever possible, minimizes pressure drop. Properly applying thread sealant also helps prevent leakage and system contamination.
Repairable actuators last longer, leak less, and reduce maintenance costs. Typically, cylinders can be sized at 60 psig to provide a safety margin. Using regulators to pressure down can reduce air costs. Installing reverse flow regulators, piped between the valve and the cylinder, provides independent pressure control for extend and retract. The non-relieving design of these regulators saves air, as well as wear, on components and mechanical devices.
Smart air preparation systems that ensure adequate airflow by servicing filtration and pressure controls are especially valuable for plants without proactive maintenance programs or resources. Drip leg assemblies (to protect equipment against water and contamination), primary and coalescing filters and pressure drop indicators and sensors can complement and support maintenance programs. And visual and electrical sensors detect pressure drops as filters clog. Clogged filters reduce flow, increasing both air and maintenance costs.
High-pressure air should only be specified where absolutely necessary. Reducing pressure when possible provides a huge savings in air costs and maintenance and improves the performance of most compressed air systems. Instead of running actuators at 80 psig (pounds per square inch gage) extend and retract, operating them at 60 psig extend and 40 psig retract will still get the job done while saving several thousand dollars per actuator per year.
One hundred psig is often applied for vacuum cups requiring only 70 psig. This is a prime savings opportunity. Furthermore, some manufacturers offer air economizing/ emergency stop vacuum solutions, enabling the vacuum to be turned off when parts aren’t present. This also enhances safety and reduces noise in the workplace.
Twenty to thirty percent of a compressor's output may be spent on leakage. Such fluctuating system pressure also causes equipment to function less effectively and decreases its service life due to extra cycling and run time. The most common sources of leaks are faulty couplings, joints, quick disconnects, hoses or tubes, fittings, FRLs, and valves. An ultrasonic acoustic detector can help detect system leaks.
Regular system audits and corresponding adjustments can reduce compressor run times if there is a reduction in demand. Such audits require minimal capital expenditures and pay off through lower operating costs, better efficiency, and improved quality.
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Article contributed by Rich McDonnel, market development manager - innovation for Pneumatic Division North America of Parker Hannifin Corporation.