Champion

The Myth:

Extending the intervals between compressed air system servicing saves money, and fixing air leaks often isn’t worth the expense.

Analysis:

Compressed air - along with electricity and hydraulic systems is an essential means of reticulating energy about any modern industrial enterprise. In Australia, around 10 per cent of the power generated is used to compress air. While this may be a surprise to some, the facts behind the true cost of air power can be even more surprising.

Consider a 22kW air compressor operating a two-shift (4000 hours per year) application. With electricity charged at 10 cents per kWh, the running cost of the compressor is $8,800 per year. If the compressor is serviced three times a year at a cost of $300 per service, an annual servicing expense of $900 is incurred. By reducing the number of services to only two per year, an apparent $300 one-off ‘saving’ can be made.

In reality, allowing the air compressor to run ‘un-serviced’ for an additional two months, twice a year, has a dramatic effect on electricity consumption. Dust begins to clog the pre-filter, air-intake filter, oil filter and the air/oil separator. This clogging is cumulative and gives rise to a decrease in performance, and an increase in electricity consumption. For every 1kPa of clogging, efficiency is reduced by one per cent.

The ‘snowballing’ effect of the clogging in these two-month periods can cause significant pressure drop, equivalent to a five per cent reduction in efficiency over a one year period. Consequently, reverting to two compressor services per year, results in an increase of $440 in annual electricity consumption cost. Servicing the air compressor three times a year instead of two actually saves the user $140 per year and, more importantly, increases the lifespan of compressor components, and reduces repair costs and the chance of breakdown.

The opportunity to save energy and money is not limited to the compressor itself. It is not uncommon to find multiple air leaks in the compressed air reticulation pipework of any given medium-sized industrial facility. The cost of producing this ‘wasted’ compressed air is often considered less expensive than the cost associated with fixing the leaks. The time and cost of hiring a plumber - approximately $400 per day - to locate and mend these leaks often deters businesses from addressing this problem. While this sounds expensive, a quick calculation would suggest otherwise.

According to the NSW Sustainable Energy Development Authority (SEDA) a 1- to 3mm diameter compressed air leak wastes $1,305 worth of compressed air per year (based on 700kPa air pressure, operating 6,000 hours per year, with electricity charged at 10 cents per kWh). Six air leaks will incur an annual cost of $7,830. By contrast, a plumber could be expected to repair all six air leaks in one day, at $400 per day. This equates to a payback period of just over 2.5 weeks - NOT YEARS! - and a return on investment over one year of 1957.5 per cent. The total saving at the end of one year is $7,430.

Conclusion:

Poorly maintained compressed air systems negatively impact a company’s bottom line. Extending periods between air compressor services and neglecting compressed air leaks results in increased operating and repair costs, shorter component life, and a greater risk of production losses. Regular servicing and predictive maintenance are the most efficient means of compressed air system upkeep, and yield lucrative economical benefits.

The above figures are approximations--actual cost/benefits will vary from application to application.