Hydraulics & Pneumatics November/December 2022

consumption and more cost. In fact, it’s directly proportional, so doubling the vacuum pressure will double your holding force and double your energy costs. Instead, it may be possible to increase the diameter of your vacuum pads in certain applications. When doubling pad diameter, your holding force quadruples, while your energy costs remain the same as there is no increase in supply pressure. The price difference between a 20 mm and 40 mm diameter vacuum pad is typically less than € 5. Vacuum ejectors with energy-saving function Some vacuum ejectors feature a vacuum pressure switch with an energysaving function that can reduce energy consumption by up to 93%. So how do they work? Well, you first define the pressure range within which you can securely hold the workpiece, for example from -65 to -55 kPa. The integration of pressure switch with energy-saving function serves to cut off the air supply upon reaching the desired vacuum level. Vacuum only generates again when the pressure falls below the lower range, in this case -55 kPa. Take a vacuum handling application involving a conventional ejector that operates at 450 cycles per hour, 10 hours a day, for 250 days a year. Such a system will consume around 9350 m3 of compressed air every year. However, using a vacuum ejector with an energy-saving function will reduce air consumption to just 638 m3 per year, delivering the aforementioned 93% saving. The potential savings are higher in short-cycle applications. Smart management To maximise the use of an energy-efficient vacuum handling system, SMC recommends that you adopt ‘smart’ ejector systems. A serial transmitted ejector manifold requires no separate input/output units to operate and avoids complex electrical wiring of the valves and sensors. Field devices can connect directly to the PLC. Via the PLC, it is possible to set and monitor the pressure values, suction or release verification, the energysaving function and the valve protection function. This concept leads to better control of your application, more valuable data, simple set-up and on-board product diagnostics, as well as easy monitoring. Technical support If you’ve ever dealt with a vacuum-based system, you’ll be aware that vacuum can be unpredictable as the interaction and the behaviour between workpiece and pad differs depending on the application. The only real way to be certain of the results is to take advantage of an expert technology supplier such as SMC, which can conduct tests at customer sites or at its laboratories located across Europe. Vacuum is frequently about trial and error regarding pressure, flow, pad size, number of pads and more, particularly if it involves special workpiece materials, so why not let the experts work it out. With energy costs rising rapidly around the globe, few can afford to ignore the energy-saving possibilities that a correctly specified and configured vacuum handling system can bring. It’s time to get a grip on efficiency. www.smc.uk COMPRESSED AIR 36 HYDRAULICS & PNEUMATICS November/December 2022 www.hpmag.co.uk SPOTLI Estimates suggest that Class 4 moisture content according to ISO 8573-1 is acceptable in the majority of compressed air system applications, thus supporting the use of refrigeration dryer technology. However, where applications demand higher levels of moisture removal, desiccant tends to be the go-to technology. The long-standing problem here is the higher cost associated with desiccant dryers, which is why HI-LINE INDUSTRIES, a UK-based leader in the design, manufacture and installation of energy-efficient compressed air purification equipment, is addressing this issue with its new Hi-Plex dual technology dryers. This hybrid solution combines Hi-line’s established refrigeration and PSA (Pressure Swing Adsorption) air treatment technologies, creating an energy- efficient system at low capital cost compared with standard heat-regeneration desiccant air dryers. So how does Hi-Plex work? Well, a Hi-line Tundra refrigeration system first removes bulk moisture via zero loss auto-drains, after which it chills the air to +1°C in the heat exchanger, condensing out all water to a +3°C PDP (Pressure Dewpoint). From here, the pre-dried air passes into an energy- efficient HPSA (Hi-line Pressure Swing Adsorption) dryer where it is further dried via adsorption to lower dewpoints of between -20°C PDP and -70°C PDP depending on end-user requirements, meeting Class 2 moisture content in accordance with ISO8573.1. As a point of note, Hi-line can add an Activated Carbon Tower for Class 0 applications. Visit www.hpmag.co.uk for the full release. t | 01283 533377 e | enquiries@hilineindustries.com w | www.hilineindustries.com HI-PLEX HYBRID TECHNOLOGY SPOTLIGHT to your air consumption and your costs. By way of example, if you use of 0.5 MPa (5 bar) main line supply pressure to operate our ZL112A ejector (with valves), your air consumption will total around 78 l/min (4680 l/hour) to achieve a maximum vacuum pressure of - 84 kPa. However, by choosing to operate the ejector at a reduced 0.35 MPa (the standard supply pressure for this type of ejector), you can cut air consumption to 57 l/min (3420 l/hour) and still achieve the same maximum vacuum pressure (-84 kPa). A significant 27% energy saving. As a point of note, while many manufacturers have yet to transition from 7 bar standard shop pressure, optimal vacuum operation takes place at an average of 4 bar, so reducing from 7 bar to 4 bar not only benefits your bottom line and the future of the planet, it will have no impact on the effectiveness of your operations. Returning to the example, if you can safely handle the workpiece with a maximum vacuum pressure of -65 kPa, you can reduce the supply pressure even further, to 0.25 MPa (2.5 bar). This would cut your air consumption to 45 l/min (2700 l/hour), delivering an impressive 43% energy saving. Use a bigger pad diameter, not higher supply pressure Some engineers make the mistake of increasing supply pressure to achieve a higher holding force, but this leads to more energy