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FEATURE HYDRAULICS & PNEUMATICS The pressure is on


Traditionally, OEMs design their pneumatic machinery and equipment for an operating pressure of 7bar. But, reducing this to 4bar can cut end use energy costs by up to 29%. Roy Schep, manager energy efficiency, SMC Netherlands, comments


A


s regulations tighten and public pressure for a more energy-efficient industry grows, the shift to 4bar will become more


common. So, when designing a machine, it makes sense to start with the components that do the work: the actuators. In general terms, these are the elements that may not perform at their best, or sometimes not at all, using lower pressure. Two variables are key: force and speed.


Actuators in most horizontal applications tend to operate at lower supply pressure because they are acting against friction, not force. So, it’s normal to size actuators for use in horizontal orientations to perform at a certain speed. In vertical applications, however, the cylinder


pressure has to overcome the load pressure. These applications tend to be more critical and usually demand specific considerations to ensure the actuator meets its intended objective. Reducing the pressure to 4bar in vertical applications may require the use of a larger bore actuator to ensure the required force. If using a larger bore size is an issue due to lack of space, SMC’s VBA series pressure boosters can provide the required pressure level in that local part of the application without having to increase the main line pressure, making it possible to use the existing actuator size. In either case, a simple calculation can indicate


the theoretical force of the cylinder: F = P x A, where F is force in Newton, P is pressure in bar and A is the effective area of the cylinder bore in cm2


. As a point of note, if working at


4bar demands a larger bore size, the saving in air consumption will offset any additional cost. But, what if a cylinder with a larger bore will


not fit with your design space? It is important to find a supplier that can provide compact and lightweight actuator solutions. SMC’s compact cylinder solutions, for example, have a lower minimum operating pressure plus energy-saving features. The other option is to use a different technology, such as a double-force cylinder.


solutions


The air flow the actuator receives controls its speed – if you need higher speed; the valve will control that. With the cylinder bore and force defined, it’s possible to select the valve size. SMC offers directional and process valves with low power consumption, making them ideal for use at 4bar. When it comes to blowers and vacuum units, higher pressure does not mean higher performance, but the opposite, which is why products like a high-efficiency nozzle can deliver


2 deSigN SOlUTiONS NOVEMBER 2022 2


notable gains. This can maximise air blow efficiency thanks to a more focused blowing impact. Governed by the Bernoulli Effect, you can improve air blow thrust by 10%. We recently saw this at a customer producing


liquid detergent. The company’s bottle un- scrambler machine housed 25 air nozzles, costing €22,441 in annual air consumption. So, the customer adopted SMC’s high-efficiency nozzles that provide the same blowing performance (flow and impact force), but with a lower nozzle diameter – thus allowing lower inlet pressure. Reduced air consumption led to savings of €6,183 a year, delivering amortisation in just 1.57 months. The same replacement on six further lines led to total annual savings of €37,098. SMC’s commitment to 4bar is also visible


with its vacuum units, which actually function at maximum efficiency when using low operating pressure. At 4bar, we ensure the vacuum pressure necessary to hold the component or product securely. Beyond this pressure, air is wasted and the vacuum unit loses efficiency. By turning up the pressure, you are not getting more force or speed, just more inefficiency.


energy efficiency Regulators can be good collaborators in the 4bar


journey, largely because we can use them to reduce the pressure even further at points where it’s possible. This might include air blow or vacuum applications, providing the machine with even more energy efficiency. Furthermore, although a pressure switch plays


no direct role in the 4bar concept, it can prove beneficial in the long run. For instance, when designing a machine for 4bar, you need to monitor pressure as the margin is low. In the first instance, pressure monitoring acts as a control measure for the machine to receive the 4bar it needs. Secondly, pressure switches can monitor air consumption and identify any pressure losses. Air leakage is something that no machine can afford, especially at 4bar.


machine development


So, when developing machinery which operates at 4bar, experts from companies like SMC can help provide the correct sizing for each pneumatic component – and ensure it consumes less energy without compromising machine performance.


SMC Pneumatics (UK) T: 0330 311 6687


Air-OPerATed dOUble diAPhrAgM PUMPS


The Finnish Thompson FTI Air-Operated Double Diaphragm pumps (AODD) range has been expanded with the addition of a new ¼” non-metallic model, available in polypropylene, PVDF and also conductive polypropylene for use in ATEX areas. Available in the UK from Michael Smith Engineers, the FT025 model


delivers a maximum flow rate of 22 lit/min (5.8gpm) at a maximum air supply pressure of 120psi (8.3bar). The FT025 extends the minimum flow capabilities of these rugged and reliable pumps and brings the important benefits of using AODD pumps to a wider range of pumping applications. These are simple to install, easy to operate, require less maintenance


resulting in lower running costs, and are self-priming so can be dry-run. They can also handle abrasive, viscous and shear-sensitive liquids and even ‘dirty’ liquids with particles up to 1.8mm (0.06”) for the FT025 model. The FT025 includes a lube-free air valve design which contributes towards the philosophy of a


simple, rugged and reliable design, the company explains. The air valve components include a low friction slide valve on a ceramic plate to allow for long-life and superior sealing, and a moulded Buna gasket which ensures total sealing and eliminates flat gasket tearing. Typical applications will include handling acids, bases, plating solutions, wastewater, paints, inks,


solvents, ceramic slip and glaze, lubricants and oils in industries such as mining, painting, finishing, ceramics, electroplating and anodising, pulp and paper, wastewater and marine, chemical manufacturing and distribution.


Michael Smith engineers www.michael-smith-engineers.co.uk


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