The challenge to manage precious energy resources is ongoing, with legislation and voluntary initiatives being introduced to help improve efficiency within industry.

However, if there’s a lack of accurate information about the current performance of a compressed air application, it’s difficult to know where to begin when looking to make improvements.

Responsible compressed air equipment manufacturers and suppliers have for many years offered customers an energy audit to assess the performance of a compressed air system but, until recently, there has been no framework for manufacturers and suppliers to stick to during an audit, meaning results could vary in terms of accuracy.

There have been concerns for some time that the lack of a formal standard allows suppliers with differing levels of expertise to conduct a compressed air audit – and for that examination to then be considered as a comprehensive system assessment.

Setting the standard

ISO11011 is designed to create a framework for the assessment process, so that auditing procedures can now be carried out on a level playing field. The new standard considers the entire air system, from the energy inputs to the task performed and classifies compressed air in to three subsystems: 

•  Supply – which includes conversion of the primary energy resource into compressed air energy

•  Transmission – which includes the movement of compressed air energy from where it is generated to where it is used

•  Demand – which includes the total of all compressed air consumers, including productive end-use applications and various forms of compressed air waste

ISO11011 sets requirements for conducting a compressed air system assessment, for analysing the data and for the reporting and documenting of the findings. A key element of the standard is to identify the roles and responsibilities of those involved in the assessment activity.

Assessing system efficiency

In compressed air systems with very large runs of pipe work and little control over system pressure, it can be difficult to manage air usage. ISO11011 assesses compressed air use, critical production functions and poor system performance. This should help to identify and quantify energy waste, the balance between compressed air supply and demand, energy use and total compressed air demand. 

Baseline performance

One of the key features of ISO11011 is the establishment of a ‘baseline’ performance of a compressed air system. The purpose of baselining is to establish the current performance levels and costs of a compressed air system, and to correlate the results with the plant’s present production levels. As improvements are made to the compressed air system, it will be possible to estimate improvements by comparing the new measurements with the original baseline.

Critical air demands

The standard considers end-use applications as part of the assessment process, some of which are identified as ‘critical air demands’. Critical air demands include those end uses of compressed air that have the potential to impact on performance factors such as product quality, production rate, scrap rate, rework cost and customer satisfaction. The standard indicates that improving the performance of a critical air demand may not be related to the compressed air aspect but more to the poor mechanical state of that end-use equipment. 

In addition, ISO11011 addresses any ‘wasted’ compressed air. This goes beyond, but doesn’t ignore, obvious leaks, which can contribute up to 35% of the generated compressed air. The standard analyses any ‘inappropriate use’, such as when compressed air is be being used unnecessarily for cooling, when a simple fan would be more efficient. 

Air treatment

Air treatment systems can cause pressure loss and leaks if installed badly, so its important that equipment will deliver the proper pressure and quantity of air throughout the system. ISO11011 looks at optimising air treatment, by assessing and validating the need for and effectiveness of treatment equipment as it is presently installed. Any opportunities for performance improvement and energy reduction will also be identified.

BCAS encourages all users of compressed air to have their systems audited in line with ISO11011 in order to ensure they receive the most accurate results possible from the assessment. This will make deciding what action to take as a result of the audit an easier process, which can then lead to a reduction in the systems’ energy consumption, often without the need to purchase a new compressor.