SAVING ADVICE - COMPRESSED AIR

Compressed air is a convenient and often essential utility, widely used in industry. However, it takes a lot of energy (usually electricity) to generate compressed air and it is therefore very expensive. For example, it costs up to ten times more to run air tools than their electric equivalent as 90% of the energy used by a compressor is rejected as waste heat.

Key Measures

  • Compressed air should only be used where necessary. Frequently it is used because it's convenient, rather than there being no alternative. Compressed air should not be misused, for example for cleaning or cooling.
  • Up to 30% savings are possible by some simple good housekeeping measures, often achievable at no or low cost.
  • The typical level of leaks on a site is 40%, yet they are often ignored as a source of waste.
  • Compressors are frequently left running when not required - even when idling some compressors draw up to 60% of their full load power.
  • Poor maintenance is one of the largest causes of poor system performance and wasted energy.
  • Producing compressed air at a pressure greater than required, or filtered and dried to unnecessarily high levels is wasteful. Higher pressure means greater losses through leaks and higher power requirement for the same delivered air volume.

Practical Tips

Listen for leaks during quiet periods. Repair leaks - most commonly found on connectors, flanges and flexible hoses.

If the compressors have hours-run meters, read them at intervals through the day to see whether you have more units running than necessary. Compare on-load hours against total run hours for idle running. Reduce unnecessary running by using or installing controls.

Ensure air inlets to compressors are ducted from the coldest source (usually outside). Reducing air inlet take by 6 °C increases output by 2%.

Ensure equipment is properly maintained - e.g. filters are changed regularly.

Use low-pressure blowers for applications such as air knives, air lances, air agitation, blow-guns etc. Never use compressed air for cleaning workbenches and floors.

Fit zone-isolation valves. These can be under time control, or interlocked to the packing/production line served, to enable parts of the site to operate out of hours without air going through the whole works.

Further information on compressed air