Compressed air is often referred to as the fourth utility. It is as essential to many sectors as a safe, reliable and versatile source of power. 

It does however take a considerable amount of energy, generally in the form of electricity, to produce the clean, dry, pressurised air that is needed for so many processes and applications. 

In this month’s update, The British Compressed Society (BCAS) outlines some of its top tips for generating reliable, productive and energy efficient compressed air:

1. Take a whole system approach

A compressed air system is just that; a system, and every element of it impacts upon its energy consumption. It is therefore a mistake to just concentrate on one aspect of the system to the exclusion of others. This will only result in missed opportunities to save energy. 

2. Find and fix the leaks

All compressed air systems have leaks, but these are often ignored as they are not an immediate health and safety hazard. 

A high leak rate causes fluctuation in pressure, resulting in hidden costs such as slower running or the stalling of production lines and also creates a noisy environment for employees. 

Operators should initially conduct an out of hours survey and walk the site listening for leaks. 

The location can be confirmed by using any of the following methods: ultrasonic leak detector, a soap solution brushed onto pipe fittings, or a leak detection spray. 

Handheld ultrasonic leak detectors are the best way to detect leaks while production is running. 

Once the location has been identified, a leak management programme should be implemented.  Leaks should be tagged, recorded on a site plan and graded according to priority, aiming to fix the largest leaks first 

A leak survey should be conducted at least twice a year to keep the problem under control and many compressed air distributors will offer a leak management service if there is insufficient in-house resource.

3. Switch off the compressor when there is no demand

Do not leave compressors on overnight if there is no demand for air because electricity will be consumed to feed leaks. Even when off-load, compressors can consume up to 70 per cent of their full load power.

4. Maintain the whole system

Effective maintenance is essential to energy efficiency. Cutting back on maintenance is a false economy, because doing so increases the energy consumed, decreases service life and reduces equipment reliability. 

In addition, the law requires all systems operating at greater than 0.5 bar with an air receiver installed, to comply with the Pressure Systems Safety Regulations 2000 (PSSR). And Regulation 12 of the PSSR requires that compressed air equipment must be maintained properly to minimise health and safety risks associated with a pressurised system.

5. Heat recovery

Only 10 per cent of the electrical energy input to an air compressor is converted into compressed air energy. The remaining 90 per cent is normally wasted as heat.

While some of this heat can be recovered and used elsewhere, beware of claims that this 90 per cent is all recoverable, useful heat. The heat output is highly dependent on the load cycle of the compressor being able to generate sufficient heat at the right times. Heat recovery is best considered once other energy saving measures have been implemented.

6. Don’t over-treat the compressed air

Dirt, water and oil are present in all compressed air systems and need removing. To save the energy and cost incurred by cleaning and drying compressed air, treat all the compressed air to the minimum acceptable level, and then improve the quality at the points of use to the required level.

For more tips on how to improve the energy performance of your compressed air installation, download BCAS’s free ‘Reducing Energy Consumption from Compressed Air Usage’ whitepaper at www.bcas.org.uk