Selecting the right air compressor for your business

Step 1: Assess the air demand

Begin by identifying the pressure range required for the different applications the compressed air will be used for.  Different tools and processes may have varying pressure needs, so consideration needs to be given to the most air-intensive demands, without oversizing the system.

The basic principle should be to operate the system at the lowest possible pressure that meets operational needs to helps save energy. Use advanced control systems to dynamically adjust pressure settings based on real-time demand.

In the food and beverage industry for example, packaging machines may require air at a higher pressure than pneumatic conveyors. Ensuring the highest-pressure requirement has been factored in is crucial.

A good way to help identify the pressure range required is to measure the total air consumption of all equipment using data logging devices.  Operators should consider both the peak demand and average usage to ensure the compressor can handle the workload without frequent cycling.

For example, in automotive manufacturing, air tools, spray painting, and assembly line equipment will consume significant volumes of air. Using a data logger can help track the peak air usage during production shifts.

Step 2: Select the right compressor type

There are a multitude of compressor types available on the market, so careful consideration needs to be given to the technology best able to deliver the performance and efficiency required.  The best option is to speak to a BCAS member who can carry out a full site audit to assess the technology that will best suit the plant demands, but here is an overview of some of the most common compressor types.

A small-scale food processing facility might use a reciprocating (piston) compressor for batch processing tasks that require high pressure but are not continuous.  These types of compressors are best suited for intermittent use and lower air volume requirements. They are robust and can deliver high pressures but may not be ideal for continuous operation due to higher maintenance needs and noise levels.

Where a consistent and reliable air supply for tools and equipment is required for 24/7 shift patterns, a rotary screw compressor is ideal.  Designed for continuous operation and large air volume requirement, they offer lower maintenance and noise levels.

Scroll compressors are ideal for applications requiring oil-free air, such as in the food and pharmaceutical industry, while centrifugal compressors can handle large volumes of gas at high pressures where a constant flow of air is required.

Also, manufacturers should consider compressors with heat recovery systems to utilise waste heat for other processes, such as space heating or water heating.

Step 3: Consider speed-regulated technology

Variable speed drive (VSD) compressors adjust their motor speed to match the air demand, leading to significant energy savings. They are most effective when air demand fluctuates and can be used very effectively in a compressed air system combining fixed load machines to handle the constant, full load demand. 

Step 4: Size the air receiver correctly

An appropriately-sized receiver prevents cycling and maintains a stable pressure to help buffer peak demand.  The air receiver size in litres should be at least 6-10 times the compressor’s free air output (measured in litres per second). The receiver should also be positioned as close to the point of use as practical to help minimise pressure drops, ensuring it remains easily accessible for maintenance and draining.

Step 5: Optimise piping and distribution

A critical component in any compressed air system is the pipework used to carry air around the network.  The pipework should be designed for minimal pressure drop, using large radius bends instead of elbows to reduce friction losses and ensure efficient air delivery to all workstations. Corrosion-resistant materials, like aluminium or stainless style for hygienic environments ensure longevity.

In additional, implement zoning to supply different pressure levels to the assembly or production line to match specific process requirement and isolate unused sections to avoid unnecessary air loss. 

Finally implement regular leak detection programmes using ultrasonic detectors to identify and fix leaks promptly, thereby reducing energy waste.

Step 6: Select appropriate air treatment equipment

BCAS’s ‘The Filtration and Drying of Compressed Air Best Practice Guide 104’ provides an excellent starting point when selecting the appropriate air treatment equipment.

Air dryer technologies should be specified based on the demands of the application, and there are multiple types to select from.  For example, a beverage bottling plant requiring very dry air may commission desiccant dryers to prevent moisture-related issues in the bottling process, whereas refrigerant dryers may be sufficient for general use.

Filtration equipment removes particulates, oil and moisture from the compressed air. The filtration level should match the quality requirements of the application, for example, to deliver breathing air standard quality for paint booth applications in the automotive industry.

Step 7: Plan for maintenance and monitoring

To keep your compressor running at optimum efficiency, it’s important to maintain it regularly. A programme of routine maintenance can save time, energy costs and expense in the long term.

Consider preventative, or even predictive monitoring - helping to identify potential compressor problems before they become a major issue. Predictive maintenance practices using IoT and AI technologies help monitor compressor performance and anticipate maintenance needs, thus avoiding unexpected downtime.

Step 8: Consider future expansion

A compressed air system is likely to operate for many years, so it’s worth considering likely future demands when specifying.  Operators should choose a compressor that can be upgraded or expanded easily to meet future air demand increases, prioritising modular systems that can be scaled up as needed.

Sites should also ensure the compressor, and its control system, can integrate with other industrial systems such as HVAC and process control, helping improve overall plant energy management.

BCAS offers a wealth of information to help operators when specifying a compressed air system.  Visit the Society’s 10% Taskforce website for free, downloadable guides to help improve energy efficiency at taskforce10.bcas.org.uk/simple-steps/ or go to the online shop to purchase a range of best practice guides at elearning.bcas.org.uk/publications/

Ashley Quarterman is executive director designate at BCAS

www.bcas.org.uk

Tel: 0207 935 2464