Take a closer look at compressed air system costs and reap the rewards

25 September, 2015

It is an all too common fact that most compressed air systems are often overlooked in a plant’s calculated cost of production. Many manufacturing and process plants are often unaware of the potential cost benefits that can result from applying best practice management techniques.

Various strategies can be deployed to improve compressed air savings and boost the bottom line. For instance, it’s well documented that using oversized valves can waste considerable energy. As a result, always consider valves with solenoid air pilot and low watt coil designs, as these can reduce electrical costs. In addition, using straight fittings, rather than 45deg or 90deg elbow fittings wherever possible can minimise pressure drop, whilst using pneumatic fittings with O-Ring seals help prevent leakage and system contamination.

Serviceable actuators

Another step towards cost-effective compressed air delivery is to select serviceable actuators as these last longer, leak less and reduce maintenance costs. Typically, cylinders should be sized at 60 psig to provide a safety margin, while the use of regulators will keep pressure down and reduce air costs further. What’s more, installing reverse flow regulators (piped between the valve and the cylinders) will provide independent pressure control for extend and retract. The non-relieving design of these regulators saves air and reduces wear on components and mechanical devices.

Ensuring pneumatic systems function properly with clean and dry air is a further recommendation that can save costs. To achieve this, plants will require an air preparation system, which includes air compressors, bulk liquid separators, particulate filters, coalescing filters, membrane dryers and hydrocarbon removal systems. Utilising an air preparation system ensures adequate airflow by servicing filtration and pressure controls; they are especially valuable for plants without proactive maintenance programmes or resources. Also, making use of visual sensors will detect pressure drops as filters clog. Clogged filters reduce flow, increasing the cost of both air and maintenance.

Of course, high-pressure air must be kept in check, and should only be specified when absolutely necessary. Instead of running actuators at 80 psig extend and retract, operating them at 60 psig extend and 40 psig retract will deliver significant cost savings per actuator, per year, without compromising performance.

Detecting system leaks

Beyond wasting pressure and electricity, leaks contribute to operating problems because of fluctuating system pressure that causes equipment to function less effectively. Leaks also help decrease equipment service life as a consequence of extra cycling and increased run time. Although compressed air can be lost through multiple system locations, the most common are faulty couplings, joints, quick disconnects, hoses or tubes, fittings, valves and FRLs (filters, regulators and lubricators). An ultrasonic acoustic detector can prove a useful tool when detecting system leaks.

As a point of note, whenever leaks are repaired, it is important to re-evaluate the compressed air system and work with air system specialists to adjust compressor controls. This often entails reducing compressor run-times to match the reduced demand.

Lack of industry awareness

In conclusion, there is a general lack of industry awareness concerning the negative impact that inadequate compressed air management practices can have on costs. For new systems, the efficient use of compressed air can be realised through better pneumatic designs and component selection, while for existing systems, aggressive best practice initiatives and maintenance programmes that fix and prevent leaks can offer the immediate payoff of energy savings and lower operating costs.

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