Pneumatics specialist Simon Agar, General Manager of pneumatic actuator, isolator and suspension specialist Air Springs Supply explains the right approach to address compressed air problems.
Energy wastage caused by avoidable compressed air leakage and poor design of compressed air systems impacts profits and environmental efficiency. They can also significantly inhibit the efficient function of air tools and industrial actuator systems, leading to increased maintenance and downtime.
According to Mr Agar, people often tend to overlook chronic malfunctioning in compressed air systems in addition to increasing their system’s inefficiency by adding branches at will. They also persist with actuators that have or are prone to seal wear and are therefore also prone to wasting air and energy.
He adds that instead of addressing the design problems that become evident when air pressure drops, people simply add more pressure, resulting in more cost.
Mr Agar has more than 20 years of experience in pneumatic actuation, including in his present role at Air Springs Supply, a national distributor for the Airstroke and Airmount actuator and isolator range from Firestone.
Firestone is a major producer of air springs that are designed to eliminate seals in conventional cylinders, which can be a source of wear and leaks.
According to Mr Agar, eliminating leaks is the best way to approach compressed air problems, with improved system maintenance and design saving as much as half of energy input costs.
The average plant with no formal leak management program will have air leaks that waste a quarter of total air capacity, going up to even 50% in extreme cases. Considering that 10% of electricity generated for industrial use goes towards the generation of compressed air, air leaks can cause serious wastage of energy.
Additionally, leaks will cause compressors to run at full load for longer, resulting in additional maintenance from increased loads and running times.
Typical leak points in compressed air systems:
- Quick connection fittings, which have O-rings to seal the hose connections: Damaged or missing rings will cause the quick connection to leak
- Inferior and poorly installed FRLs (filter, regulator, lubricators), which are frequently used immediately before air tools and other air equipment can cause leaks
- Bad welds or old welds on pipe joints and pipe flanges can break down and leak because of age or improper welding
- Timer-controlled condensation drains that remain open longer than required waste air
- Float or mechanical type condensation drains can also malfunction because they have parts in constant contact with the condensation
- Manual condensation valves are sometimes deliberately left open to keep water out of the system, wasting compressed air
- Air piping valves may leak if the stem packing is worn
Firestone Airmount isolators and Airstroke range of actuators from Air Springs Supply provide efficient solutions to both the compressed air cost and the breakdown issue.
Containing no seals, shafts or internal moving parts to break, wear and disrupt production, the Firestone technology is suitable for plants ranging from metals, minerals processing and electrical components to food, beverage and primary processing.
The tough rubber and fabric-reinforced isolators and actuators are balloons or bellows engineered for particular tasks including simultaneous high speed actuation while eliminating up to 99% or more of Noise, Harshness and Vibration (NVH) from noisy equipment. The single, double and triple-convoluted and rolling sleeve Airstroke designs are made to the same rigorous standards as the air springs used as suspension springs in heavy vehicles.
The range available to manufacturers and processors throughout Australia extends from the largest, 40,000kg capacity models down to palm-sized Airomatic mini actuators for delicate jobs requiring a clean actuator that doesn’t need lubrication and can cope effortlessly with high-repetition tasks.
Typical design weaknesses in compressed air systems
Even with proper leak management, an airtight compressed air system can still be wasting energy because of poor layout.
Not having a properly specified and sized ring system feeding and efficiently circulating air is a major problem. Some plants use incorrect pipe sizes, further increasing friction losses and congestion.
Internal corrosion and congestion pose great risk to the purity of products being processed, or to devices receiving the air (including actuators, isolators, tools and valved equipment). Clean, low-friction alternatives such as stainless steel, copper or polymer are recommended where corrosion or congestion is acute.
An important factor contributing to the high cost of compressed air is frictional losses with about 35-55% power consumption going towards overcoming these losses. Pressure losses can be serious. For example, a power tool designed to deliver its optimum power at 7 bar will only be about 60% efficient if the pressure is reduced to 5 bar.
When designing a compressed air system, one needs to ensure the system can be easily changed according to production needs. Pneumatic system layouts have to be able to accommodate new tools, new production demands, and all the rapidly fluctuating demands of just-in-time manufacturing or busy workshops.
If the plant is designed with a system that is difficult to change, or demands excessive skilled labour to assemble and disassemble, it may lead to extra costs, says Mr Agar.
Compressed air systems used for high-repetition tasks such as stamping and forming can achieve multiple benefits from using air springs as an alternative to conventional pneumatic cylinders.
Key benefits of air springs:
Air springs can be used instead of more expensive hydraulic systems when applying large forces with the larger sizes allowing force up to 40,000kg each using only 7 bar air pressure. Air springs are available at less than half the cost of a pneumatic cylinder with equivalent capabilities.
Air springs can be installed in a very compact space and extended to more than twice their starting height, providing great benefits in floor-mounted lifting devices.
Side load flexibility
Air springs have a flexible, compliant bellows wall instead of seals or guides with the bellows following the path of least resistance. This ensures users don't have to worry about side loads caused by misalignment.
Ease of attachment
Since the bellows bends, bead plates don't have to remain parallel, simplifying attachment.
The zero-seal design eliminates friction unlike traditional cylinders where the sliding seals can stick and cause a jerky motion when a constant force is applied to a moving object.