A key area for cost savings
September 1st 2008

Compressed air is vital to a multitude of manufacturing processes – yet the process of compressing air can be highly wasteful. Ian Ritchie, managing director of Brammer UK, examines how significant cost savings can be achieved through the use of the latest technology

More than 10% of electricity supplied to industry is used to compress air – whether for cooling, drying, removal of scrap product, removal of contamination, or vacuum generation. In some cases, it is up to 30% of total energy usage, yet of the total energy supplied to a compressor, as little as 8–10% may end up being converted into usable energy to power equipment, making it a highly costly energy source.

Leaks, poor maintenance, misapplication and poor control are all areas where compressed air is commonly wasted, yet historically many companies have failed to address these areas and take the necessary steps to optimise efficiency in compressed air production and usage – and have ended up facing higher energy bills as a result.

Partly because compressed air is convenient and easy to use, and partly because air is often perceived as a free commodity, it is often overused.

However, with maintenance typically accounting for as little as 7% of the total costs of running a compressor over a 10 year period, it is easy to see how regular, thorough, maintenance can help drive down energy costs in compressed air production.

In fact, reducing air leaks is commonly the single most important energy saving action for many sites.

Indeed, when the cost of all leaks and wastage due to inadequate maintenance is calculated, the outlay for detection equipment and replacement parts is almost always justified.

Not only do leaks present safety issues through blowing air and noise, they can interrupt production through equipment failure and create additional costs through fluctuating system pressure, reduced service life and increased maintenance, and the requirement for excess compressor capacity.

Leaks occur in hoses and couplings; pipes, flanges and pipe joints, and pressure regulators; manual condensate drain valves and shut-off valves which are left open; and from air-using equipment left in operation when not needed.

Compressed air audits can help manufacturers improve energy efficiency – by removing leaks, using less energy to create the same amount of air, providing practical advice and ensuring compressed air is used efficiently. Brammer's technical specialists have successfully conducted compressed air surveys for customers across a wide range of industries, often identifying savings that can amount to thousands of pounds per year in reduced energy costs.

Every leak in a compressed air system produces a sound pitch which is often impossible to hear with the human ear over the background of a noisy factory.

However, this output can be detected and read by state-of-the-art ultrasound equipment, with each leak tagged and numbered.

By then undertaking calculations involving the running conditions of the compressors (length of time operational each week), electricity cost, the pressure of the compressed air system, and compressor generation efficiency, the cost of the leak – and thus the potential cost savings created by repairing it - can be fully quantified, by machine, department, area or even factory.

This data can be presented in a dynamic document which, as leaks are fixed, is updated accordingly. Ongoing monitoring can also be provided by fitting an air flow meter to the system before the air preparation equipment. This ensures a proactive approach to dealing with future leaks - a lasting solution, by immediately identifying any increases in air usage which can then be investigated and remedied.

Further savings can be achieved by examining all applications and establishing whether compressed air is actually needed at all. Using compressed air for drying, for example, is often highly costly compared with blowers, or even using the rejected heat from the plant compressor.

Electrically powered angle grinders are also often far more efficient than their compressed air driven counterparts.

Compressed air is also used as a means to blow swarf, dust or shavings from machinery – a solution which may be quick and easy but is certainly not low in cost.

Developing a compressed air usage policy in conjunction with an expert equipment supplier, combined with regular planned maintenance based around comprehensive audits, can dramatically reduce compressed air usage – and energy costs, with significant impact on the bottom line.

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