7 steps to pneumatic energy savings

Up to 73% of the total cost of ownership (TCO) of a compressed air installation can be attributed to the cost of energy consumed by the compressor and ancillary equipment over a ten year period. Compared to the 20% allocated to capital and installation costs, and just 7% for maintenance, energy consumption represents a significant opportunity for cost savings. Libby Peacock (Product Manager – Pneumatics) of Brammer looks at the reductions in cost which can be realised by implementing seven achievable steps.

Despite the high cost of generating compressed air – only around 10% of energy supplied to a compressor is converted into usable energy – pneumatic systems typically suffer wastes of around 30% of compressed air through leaks. Additionally, air is seen as a free resource and therefore used liberally, without the true costs of compressed air being acknowledged. However, air leakages and wastage can be easily addressed through the following seven measures.

1 – Select the correct components

While often seen as a complete solution due to their ease of use and installation, in some applications such as the use of air tools, quick release couplings may prove a drain on resources. Switching to high-flow couplings and low-friction tubing could increase the productivity of air tools by some 50%. On average, making this simple replacement has resulted in energy savings of around 32% - equating to a CO2 reduction of 7.3 tonnes, and a cost saving of £15,000 for customers in less than a year. Purchasing decisions are understandably often based on price, however energy efficiency is often compromised as a result – manufacturers should always weigh up the complete lifecycle cost of a component against price when purchasing to ensure that short-term cost savings do not give way to long-term inefficiencies. As one example, single-acting cylinders are often all that is required of a pneumatic system and can help reduce air consumption, while cylinders with oval and rectangle piston rods are known to suffer more leaks than round piston rods – a simple change which can uncover meaningful energy and cost savings. However, ‘futureproofing’ is also a worthwhile consideration – if production demands are likely to increase, future capacity must be planned for to ensure that short-term gains are not made obsolete.

2 – Ensure the correct drive size

Opting for tubing just one size smaller can successfully reduce both air consumption and power loss – and in more than half of all compressed air applications, the pneumatic drive is too large for the intended purpose. Savings of around 35% have been achieved simply by downsizing the pneumatic cylinder, which could add up to a £2,200 cost reduction and 11.92 tonnes CO2 saving over the course of a year.

3 – Reduce the pressure

Incorporating pressure regulators into a pneumatic system can very quickly pay dividends, with cost savings of up to £1,100 per year being achieved – a saving of 22% coupled with a 6.02 tonne reduction in CO2. In fact, a reduction in pressure of just 1 bar can achieve roughly 15% savings depending upon the application. Generally speaking, full force is only required in one direction meaning that, for the return stroke, pressure can be halved with no negative consequences. Often, the OEM’s requirements will exceed that of the actual pressure at which the pneumatic component operates, meaning the pressure can be reduced by installing a pressure regulator to the device. As well as wasting expensive compressed air, operating at too high a pressure can increase wear on the components leading to burnout and the associated maintenance and replacement costs, meaning that effective compressed air management can result in indirect cost savings.

4 – Recover lost energy

Utilising the methods common in industry-leading motor racing cars, waste exhaust air can easily be used to replace open pipes using coupled intermediate circuits. For example: an open pipe used for easing labels on to bottles can be costly, when a short burst of air from a valve exhaust port will suffice.  While the cost savings here might be modest – around £250 per year – the CO2 savings can top 3.5 tonnes, helping to achieve carbon footprint reduction targets.

5 – Cut tubing lengths

Using low drag tubing can increase air flow, and reduce pressure drops. This has had phenomenal effects within the aerospace industry for example where air tool productivity is paramount.  In many applications, tubing lengths can be reduced by up to 50% with no adverse effects, leading to a reduction in air leaks around fittings and a potential CO2 saving of up to 13 tonnes per year – a cost reduction of up to £2,300.

6 – Switch off and save

According to the Carbon Trust, pneumatic equipment left idling can consume between 20 and 70% of its full load power – a staggering use of compressed air when not in use. One of the earliest adopted methods of energy saving was motion-activated lighting – or, more simply, signs advising staff to turn off lights when not in use. Applying the same responsible usage principles to pneumatic components, either overnight or during scheduled breaks, can reduce CO2 emissions by up to 3.14 tonnes per year and deliver a saving of £2,000 (10%). To simplify switch-off, time-operated solenoid valves can be implemented which allow the operation of pneumatic components only if a subsequent piece of equipment is in use. Alternative methods of shutdown include sensor-operated interlocks which detect the need for compressed air equipment to operate, isolating or applying the air as appropriate.

7 – Stop the leaks

Compressed air leakage is most commonly attributed to: shut-off or manual condensate valves left open; failed valves; leaking hoses and couplings; strained hoses; regulator leakages; and leaking pipes, flanges and joints. As well as the costs of wasted compressed air, leakages are noisy, cause vibration and are also a safety risk to workers. In a well-performing system, leakages can account for between 5 and 10% of the air supplied – however most systems record a loss of some 40-50% of the air input. Ongoing air leak surveys are therefore the single most effective method of reducing both compressed air costs and the energy consumption associated with its generation. Once fixed, a leak cannot be considered ‘cured’ as reoccurrence is common, meaning that monitoring must be an ongoing feature of any facility-wide maintenance programme.

With our technical team of experts, Brammer can help manufacturers monitor and measure these changes to demonstrate real value. For further information, please visit www.rubix-group.com

All cost and energy savings are compiled from the average figures of Brammer customers and from our suppliers.

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