A to Z of compressors

A is for audit. The only way to work out whether your site is airtight or a gas guzzler is to analyse use. Air system suppliers offer to test systems to spot leaks and check whether supply matches demand. Manufacturers can view usage patterns and look to identify potential energy savings. Tests are often free of charge. B is for burning money. Some sites simply don't make the link between air usage and energy bills, according to suppliers. WM was told of many manufacturers who simply respond to a leak in their system by whacking up the compressor. One site has even been spotted letting workers take a cold air shower under its pipes to cool off during hot summer shifts. An expensive wash when you consider one open pipe running at 80psi will cost you nearly £70 a week. Contaminants are a constant threat in all types of compressed air systems. Units can fall prey to several types of contaminants including oil, water vapour, dirt and micro organisms. Each must be removed or reduced to ensure the system runs effectively. Filtration systems can be installed at the point the air is generated and where it's used to combat contaminants. Determining the correct size of compressor for your factory is vital and will save cash in the long run. A king size generator could mean a royal hike in energy bills, so make sure you need the excess capacity by carrying out an air audit (see A). Energy accounts for more than 80% of a compressor's total lifetime costs, according to industry figures. Energy recovery can be a useful technique in boosting your site's efficiency and reducing bills. The technique involves recovering waste heat from your air compressor and using it to power other amenities like heating workshop areas or domestic water. F is for fixed-speed compressor. This traditional and most popular style of compressor delivers air at a constant rate. It's best suited to sites that don't experience peaks and troughs in production demands (see box overleaf). G is for government loans. Cash is available to help small and medium-sized manufacturers to upgrade their air supply systems. The Carbon Trust offers interest-free business loans to qualifying firms (www.carbontrust.co.uk). The government also offers the enhanced capital allowances (ECA) scheme. This allows manufacturers to write off 100% of their investment on qualifying energy-saving compressors against their taxable profits of the period during which they make the investment (www.eca.gov.uk). H is for home. Finding the right one for your air compressor is just as crucial as picking the right model. Units should be positioned as close as possible to where air is being used to cut the risk of leaks from piping. Newer machines have been designed to operate more quietly, allowing systems to be placed near production lines without employees having to reach for their ear protectors. When positioning your unit also take into account the risk of contamination. Avoid being close to car parks where vehicle exhausts can introduce oil vapour or even carbon monoxide. Incorrect line set-up is one of the most common mistakes made by manufacturers, say compressed air system suppliers. Firms generate more air than they need for the job and end up paying for the oversupply. Obstinacy reigns supreme among some manufacturers, suppliers say, with operators demanding 3,000 cubic feet per minute of air flow on the less than scientific basis that 'that's what they've always had'. J is for joined-up thinking. Manufacturers are urged to take a holistic view on compressed air. It's pointless paying top dollar for a turbo charged compressor if you have a decrepit piping system with more leaks than a Welsh farming fair. Get your entire system audited, keep scrutinising performance and, crucially, check that your demand for compressed air hasn't significantly changed since installation. Keep up to date with filters. Blocked filters limit air flow and can increase the power used by compressors by 4%, according to the Carbon Trust. L is for leaks. Ignore them at your peril. Experts estimate that even a tiny 1mm leak in a 7 bar compressed air system can add almost £450 per year to your energy bills. Compressor suppliers claim a staggering 30-50% of air produced goes just to servicing leaks. Firms offer a leak detection service to spot system failures. Maintenance is key: take care of your compressor and it will take care of you. Following a proper maintenance schedule could boost the unit's lifespan with well-tended systems lasting over 20 years. Site managers should also keep a watchful eye on efficiency by continually auditing the compressor's output. N is for nozzles. These energy-saving devices can be fitted to compressed air pipes at the point of use. The nozzle acts like a turbocharger by amplifying the amount of available air without putting extra demand on the compressor. With a pack of five nozzles costing less than £100, it's one of the more economical ways to curtail your energy costs. Ois for oil or oil-free compressors. Oil-based models inject oil during the compression process. They are cheaper to buy but have higher operating costs as they require a higher working pressure. Oil-free models use atmospheric air as part of a two-stage compression process. The technology is more expensive, but also more efficient, generating greater savings over time. P is for pipework. Poorly fitted pipes can cause slumps in air pressure. Classic mistakes are fitting the wrong size pipes, introducing too many bends or fittings and trying to extend the piping over excessive distances. Old piping is also a breeding ground for contaminants. Q is for quick fixes. When it comes to purchasing your compressor there simply aren't any. That bargain compressor could prove to be anything but if it saps energy and requires constant maintenance. Buy on the basis of operational efficiency and you'll claw back any excess outlay over the lifecycle of the product. R is for return on investment (ROI). How quickly you achieve payback on your compressor will be largely determined by the health of your existing system. Those sites with antiquated compressors pumping out reams of excess air through ancient piping could achieve payback within a very short time, possibly weeks or months. More advanced operators could be waiting a little longer. But suppliers claim that it's a question of if, not when you'll get your money back. Strip out any redundant pipework or valves in areas of the factory that aren't being used to save on your energy costs. T is for turn it off. Switching off compressors during breaks when no air is needed will also save you money. U is for ultrasonic leak detection. Testers use ultrasound to pinpoint air leaks that may be inaudible to human ears. V is for variable speed compressors. Variable speed units match air supply to demand in a bid to reduce energy consumption during lulls in production. The technology has been billed as the next generation in compressed air production, offering greater efficiency than fixed speed units (see box, p48). W is for what a waste. Only 10% of the electricity supplied to compressors is converted into useful energy, according to industry figures. X is for finding the X factor - not as in Simon Cowell and co, but the secret formula for maximum efficiency in your compressed air system. The magic number will vary from manufacturer to manufacturer depending on working environment and output demands. An inspection from an accredited air supplier is the best place to start your search for the X factor. Zigzags: try to avoid them in your pipework as every bend reduces efficiency. Keep piping as straight as possible and you'll maximise your air supply system's efficiency. n The A-Z was compiled with the aid of compressed air equipment suppliers and industry experts: our thanks go to Atlas Copco, Meech, CompAir, Mattei, Parker Domnick Hunter, ABB, Brammer, BOGE and the Carbon Trust