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Compress energy costs through an air audit
With electricity costs continuing to rise, the energy efficiency of compressed air systems is an important consideration for many businesses.
An inefficient or poorly maintained system can waste a significant amount of compressed air and energy. A compressed air system audit can help identify where these losses are occurring and where improvements can be made.
An air audit looks at how compressed air is generated, distributed and used across your site. It can help identify unnecessary energy use, pressure losses, leaks and other issues affecting system performance.
Here are ten areas to consider when assessing the efficiency of your compressed air system.
1. Find and repair air leaks
Studies indicate that as much as 50% of the compressed air produced in industry can be lost through leaks. Finding and repairing these leaks can significantly reduce the amount of compressed air your system needs to produce.
In our experience, plants without a structured compressed air leak management program can have cumulative leak levels equal to 30–50% of total air demand. An 8–12 cfm leak alone can cost approximately $800–$1,200 per year.
Nessco Pressure Systems offers a leak inspection program to help identify leaks throughout your compressed air system so they can be addressed.
2. Check your actual air requirements
Production requirements can sometimes overestimate the amount of compressed air or pressure a system actually needs.
In many cases, one process requires a higher minimum pressure, which then determines the operating pressure of the entire system. For example, most of a plant may only require 80 PSI, while one process results in the complete system operating at 98 PSI.
Where only a small part of the system requires higher pressure, a secondary high-pressure unit or appropriate booster may be a more efficient solution than operating the entire plant at the higher pressure.
The system should be designed around actual compressed air demand rather than compensating for individual pressure requirements across the whole network.
3. Check tee connections
One relatively simple improvement is replacing tee connections with directional angle entry connections where appropriate.
When a compressed air feed line enters another airline at 90°, the resulting turbulence can cause a pressure loss of around 3–5 PSI. Across a larger compressed air network, these losses can add up.
In the compressor room, back pressure can also send a false unload signal to the controls. This may cause a compressor to unload prematurely or result in additional compressors running unnecessarily.
Using a 30–45° directional angle entry instead of a tee can help eliminate this pressure loss, with relatively little additional cost.
4. Check your compressed air piping
Convoluted pipework, restrictions, ageing pipes and incorrect pipe sizes can all contribute to pressure loss.
In a well-designed system, the pipework connecting the compressed air supply with the process and distribution headers should minimise pressure loss.
Piping can be a particular issue in older facilities or sites that have expanded over time. Cast-iron piping can corrode internally, releasing rust and scale into the compressed air system and creating restrictions.
In some cases, replacing a section of pipe can make a noticeable difference. When upgrading pipework, make sure the pipe diameter can deliver the required airflow with minimal pressure drop.
5. Avoid excessive system pressure
Operating a compressed air system at excessive pressure increases air leakage, energy consumption and operating costs.
Increasing system pressure to compensate for capacity problems can have the opposite effect. It increases compressed air demand and may make the underlying problem worse.
There is also a proportional relationship between system pressure and power consumption. Every additional 10 PSI of pressure can result in approximately a 5% increase in power costs.
Higher pressure can amplify existing system problems rather than solve them. Reducing system pressure where possible means less compressed air needs to be produced, which can reduce compressor running hours and overall energy costs.
6. Make sure you have sufficient air storage
Insufficient compressed air storage is another common system issue.
Across manufacturing and processing facilities, the value of an appropriately sized air receiver and correctly designed compressed air pipework can easily be underestimated.
Air receivers provide a first stage of moisture separation, helping maintain compressed air quality. More importantly, they store compressed air to help meet periods of peak demand and reduce excessive compressor cycling.
7. Review how compressed air is being used
Unregulated or inappropriate use of compressed air can consume a significant amount of energy.
Compressed air can cost considerably more to produce than using electricity directly. For this reason, it is worth reviewing applications such as air-powered cabinet coolers, blow-offs, vacuum generators, mechanical pumps, air motors, hoists, vibrators, aeration and spraying.
Open blow, refrigeration and vortex cooling may be replaceable with heat tube cabinet coolers, potentially saving 3.5–4 kW on an average 30 × 24 × 12-inch cabinet.
Where appropriate, venturi air amplifier nozzles or air inducers can also reduce the amount of compressed air required for blow-off applications by 50% or more.
8. Review air-operated pumps and pulse cleaners
Air-operated diaphragm pumps tolerate demanding operating conditions and can run dry, making them useful in many industrial applications.
However, it is worth considering whether compressed air is the best option for each application. Electric motor-driven diaphragm pumps are readily available and may perform the same task more efficiently.
Where air-operated pumps are required, controls can shut them off when they are not in use. Pumps can waste significant amounts of compressed air when they continue operating without pumping anything.
It is also worth checking whether each pump operates at the lowest suitable pressure. Simple controls can increase pressure when required rather than maintaining higher pressure continuously.
9. Remove obsolete restrictions
Clogged filter elements, neglected manual drain traps and old separator cartridges can cause significant pressure drops. They can also affect system capacity, reliability and compressed air quality.
Equipment that remains installed after it is no longer needed can create similar problems. Old flowmeters, filters and separators are sometimes left in compressed air networks even though they are no longer in use.
Without regular maintenance, these items can accumulate sludge, rust and scale, creating increasing restrictions and pressure drop. The system then needs higher header pressure to maintain the required pressure at the point of use.
Removing unnecessary restrictions can help improve airflow without increasing compressor pressure.
10. Maintain your compressed air system
Poor compressed air quality can affect equipment, processes and overall plant operations.
Compressed air should be clean, oil-free and dry where required by the application. Maintaining this air quality requires regular servicing of filters, separators and dryers.
Neglecting recommended compressor servicing can allow oil and other contaminants into the plant air supply, potentially causing problems such as oil at tools or fisheyes in paint finishes.
Air/oil separators, filters and other service items should be replaced in line with manufacturer recommendations rather than waiting until they become blocked and cause pressure loss or other system problems.
Compressed air audits by Nessco Pressure Systems
Nessco Pressure Systems provides compressed air system audits to help identify leaks, pressure losses, restrictions and other areas that may be increasing your energy use and operating costs.
Our technicians assess your compressed air system and provide a report outlining what we find, along with practical recommendations for improving system efficiency and reducing running costs.
An air audit can help you better understand where your compressed air is going and identify opportunities to improve the way your system operates.
To discuss an air audit for your compressed air system, call our service team on 1300 290 638.
