Are your workshop profits disappearing into thin air?

Compressed air systems are energy hungry. Ensure your systems are working efficiently and are leak free and you could be in for a breath of fresh air the next time your energy bill arrives.

Compressed air systems are often ignored until something goes wrong or they fail to keep up with demand.

With 73 per cent of the cost of a compressor down to energy use, significant cost savings will be made by improving energy efficiency. As well as boosting your system’s performance, you will also lower your businesses’ carbon footprint. Energy efficiency will also increase the proportion of compressed air that is available for use and cut down on unnecessary wastage.

Improve efficiency
Do you have a compressed air system that is fulfilling needs but could work more efficiently? The optimisation process may only involve a small investment but can provide significant energy savings and costs.

Review air demand
Are there any inappropriate uses? Compressed air is often used for jobs because it is easily available but it is a very expensive form of energy, it is cheaper to use alternatives. For instance, instead of using a nozzle gun for blowing or cleaning, you could use an air knife, induction nozzle, low pressure blower or a broom or a brush.

Maximum pressure (KPal)
Identify the highest maximum pressure required by your system. Any less and your equipment may not function properly; any more and the system is running at a higher pressure than required and costing you money.

Average flow (inL/S)
Add the average flows of all equipment on your system. Although the actual demand fluctuates, any rapid increases in demand can be met by stored capacity in the air receivers. So, this is the flow that your compressor should be capable of producing continuously.

Air quality
If most of your equipment uses low-quality air while you have a few pieces of equipment that require high-quality air, such as breathing air, then consider moving that equipment on to a point of use system with a much smaller compressor and dryer. This will save on energy costs, as you will be using less energy in treating the air for your entire system.

compressor energy use
This is relatively easy to find out either by using a demand analyser of suitable meter to measure the average power (KW) of the compressor system over a test period.
Use a clip-on ammeter to measure the instantaneous currents on each phase and calculate an average phase current. 

Measuring the profile
To gather an accurate load profile, the airflow from the compressor must be measured at various points over a typical use cycle.
This can be a time-consuming process so you could use a compressed air service provider to carry out an air audit for you.

Analysing the profile
Once you have gathered your compressed air system profile you can work out the maximum demand for each piece of equipment and how this compares to the maximum load as a percentage.
A key performance indicator is that the lower the kW/L/s the more efficient the system is.

Reduce leakage
Leaks can waste up to 50 per cent of the compressed air produced by your compressor. When you have found leaks, keep track of them and fix the worst ones first.

Pressure drop
Pressure drop is another major cause of inefficiency. A compressed air system that is performing well should have a pressure drop of less than 10 per cent between the compressor outlet and all points of use.

Review air receivers
If you have added equipment since installing your air receiver, it may not be large enough. If your receiver is too small for your air demand needs, the compressor will be running longer than it needs to.

Article information provided by Sustainability Victoria. Download a detailed PDF on maximising air compressor equipment efficiency from its website www.resourcesmart.vic.gov.au.