At the recent Fluid Power Conference in Cleveland, Phil O’Neil of Bosch Rexroth’s Pneumatics group in Lexington, Ky., offered these sensible tips for boosting the energy efficiency of pneumatics used in industrial machines.
1. Bigger isn’t always better. It’s common practice to oversize pneumatic components, even though overdimensioning leads to unnecessarily high air consumption – as well as higher purchase and operating costs. Reducing cylinder diameters helps save air volume. Use online configuration tools, calculation programs, and energy saving calculators to determine what component dimensions are actually needed for an application.
2. Regulate pressure. With pneumatics, energy is frequently wasted when too much pressure is applied to tasks that do not require high force. In many applications cylinders generate high push forces but retract under no-load conditions. Adding a pressure regulator between the valve and cylinder port to reduce the retract pressure can significantly reduce energy consumption – in some cases well beyond 30% per cycle.
3. Regenerative circuits. For some applications that require pressure for a load in both the "push" and "pull" stroke directions, installing a regenerative air-savings system can cut air consumption in half. Rather than installing a pressure regulator, instead, the air in the load side of the cylinder is recirculated back into the other side of the cylinder to do work.
4. Minimize leaks. Leaks are costly. For users seeking to improve the efficiency of the pneumatics on their machines, the low-hanging fruit is finding and fixing leaks. Leaks are commonly due to factors such as valve design (lapped spools have inherent leakage) and deteriorating seals. Installing automatic air-reduction control is another option for significantly increasing machine efficiency. Most existing installations have no automatic means of shutting off air to machines when not in use, and having maintenance personnel individually turn off air to specific machines is too cumbersome.
5. Decentralized valves. Centralized valve manifolds have a reputation for being cumbersome and using long air lines that consume a lot of energy. Small, decentralized valve modules installed close to the actuators offer greater efficiency. Concentrating pneumatic functions prevents pressure losses through long lines from the control cabinet to the pneumatic drive. Tubing connections can be significantly shorter. Resulting energy savings of 35% are typical.