Pneumatic systems: Boosting efficiency

Reducing energy consumption is important with legislation and the rising cost of electricity creating a desire to be as energy efficient as possible. Every year, the UK industrial sector uses over 10TWh of electricity to compress air - equivalent to more than five million tonnes of CO2. Since pneumatics make up a sizable proportion of a plant’s energy consumption, taking the steps to minimise wastage and leaks whilst maximising air flow in the system is vital.

The importance of sizing

Industry is smarter today when it comes to applying the right sized components. Engineers realise that large, pipe-sized components are no longer the default choice when designing pneumatic systems. A standard air line filter, for example, uses centrifugal action in the head to prevent water and other particles from contaminating the line. If the filter is sized too large, the centrifugal action is not robust enough to remove the water; sizing that is too small will result in a very noticeable pressure drop. 

Rethinking the plumbing

In many pneumatic systems, piping runs down from the header into the application, and this is often connected by a ‘quick-coupler’. These are convenient if there’s a need to regularly uncouple devices, but they tend to have high rates of pressure loss, which can add to system issues. Occasionally, corrosion can build up inside steel pipes due to water contamination. This can clog the quick couplers, so converting to plastic derivatives, or changing to standardised aluminium fittings and links may be beneficial.

Dual pressure approach

Most applications are still set-up with one supply pressure and a dual exhaust arrangement. Although this gives optimal exhaust conditions, it may not be the best configuration for many industrial applications. An alternative technique known as the dual pressure approach, is suited for applications where the same force is not required for extend and retract conditions.

Changing filters

Regularly changing filters contributes to optimising efficiency. Typical commercial primary filters in a pneumatic circuit are designed to remove particles as small as five microns. Many filters also employ a spinning action to extract water droplets.

Initially, a particulate filter might be sized for around two pounds of pressure differential. However, when contamination starts to coat the outside of the element and the inner surfaces, part of the orifice will close up dropping the differential. 

Many users will take the element out and clean it to get the system back in service. This is not a good idea because a lot of the contaminants are on the inside and simply can’t be reached – replacement is always best. 

Clean, dry air

There are different mechanisms to reduce the amount of water going through the pneumatic system, but one of the main starting points is using a dryer to cool the air and allow the water to condense and fall out. Putting a dryer into the system won’t eliminate all of the water, but will remove the bulk of it. Particulate filters clear out the remaining water and dust in the system. 

Minimising pressure loss

Pressure leaks can occur all over the plant and be difficult to find or hear. Leaks may emanate from a fitting that hasn’t been tightened adequately, from a crack or a cylinder that has a leaky seal. Just one leak can cost thousands of pounds a year. 

The ideal strategy is for industry to implement a rigorous system for identifying and repairing leaks during scheduled downtime. Pro-active leak detection is the most economical and effective method for reducing compressed air costs.