Reducing energy consumption is a priority in most every manufacturing plant and industrial facility, as no company can afford to throw money away using machines and processes that waste energy. Because pneumatic systems are ubiquitous throughout manufacturing and can account for a large share of a plant’s power costs, it is extremely important that they run efficiently.
Unfortunately, many users have the mindset that pneumatic systems are inherently inefficient, and so overlook opportunities for energy savings. In addition, some manufacturers of industrial equipment and robots tend to focus on ensuring the pneumatic systems perform their intended functions, and in the process neglect efforts to reduce operating costs. These OEMS should instead recognize that plant operators are becoming more concerned with total cost of ownership (TCO), of which energy cost is a major component. These customers know that energy usage can account for up to 75% of machine and robot TCO, and they’re looking to suppliers to help them reduce that bill.
The old business model of only caring about performance and not about efficiency is dying. In the long run, OEMs that include energy efficiency as part of the overall performance of their pneumatic systems will be better positioned to succeed than those that neglect TCO.
Fortunately, both OEMs and users can improve the energy efficiency of pneumatic systems, with tactics that range from better engineering decisions in the design stage to adjustments and maintenance on existing systems.
According to data from the U. S. Department of Energy, manufacturers spend over $5 billion each year on energy for compressed-air systems. By optimizing these systems, companies can reduce their compressed-air energy consumption by anywhere from 20 to 35%. (The DOE offers guidelines for determining the cost of compressed air in a plant, as well as tips on how to reduce compressor energy consumption. Visit www.energystar.gov/buildings/sites/default/uploads/tools/compressed_air1.pdf for more information.)
Correctly sizing pneumatic-system components helps cut costs in several ways, as each component can affect other parts of the system. For example, undersized control valves may initially be cheaper than larger, right-sized units, but they require the air compressor to work harder to get the proper pressure to the actuators.
On the other hand, while some oversizing is necessary to compensate for pressure fluctuations and air losses, grossly oversized components account for one of the biggest energy drains in a pneumatic system. If an engineer simply oversizes from a 2 to 3-in. cylinder, for example, required air volume will more than double. Correctly sizing a cylinder can reduce its air consumption by at least 15%, which becomes even more significant in systems with many cylinders that cycle thousands of times over their operating life.
In general, most loads and speeds require only 25% additional capacity to ensure proper operation. While many calculations and considerations go into right-sizing components (such as whether a load is rolled or lifted), software packages, online calculators, and even iPhone apps can assist with computations. By spending a little more time in the design phase, OEMs can deliver substantial energy savings to their customers.
Right-sizing pneumatic components will not only increase customer satisfaction, it lets OEMs cut their own expenses. Larger and heavier components use more energy and create a larger footprint, which no manufacturer likes, and they cost more up front.
As compressed air flows through typical circuits, air pressure drops due to changes in demand, line and valve-flow resistance, and other factors. But many of these losses are simply because the distance between the compressor or supply point and the actuator is longer than necessary.
Designs that use the shortest tubing possible can reduce energy consumption as well as cycle times. Typically, tubing between control valves and cylinders should be less than 10-ft long. Longer lengths require more pressure so that force, speed, and positioning capabilities aren’t compromised.
Another way to eliminate unnecessary consumption is ensuring actuators use only the pressure needed to perform a task. Sometimes, operators on the plant floor increase supply pressure in the belief that it improves performance. However, all this does is waste energy and money. Installing sensors that monitor pressure, and pressure regulators that maintain correct settings, can keep pressure within the minimum and maximum parameters.
Many engineers also design systems that deliver more pressure than needed to the actuator. Regulators that control pressure to individual pneumatic cylinders will increase energy efficiency, in many instances generating savings of up to 40%.
The same holds for complete machines. OEMs typically design standard equipment to accommodate users who need the highest forces. Adding pressure regulators lets OEMs more accurately size components while still meeting a range of performance requirements.