Efficient use of compressed air is an area where many manufacturing operations can make considerable savings, and it doesn’t have to be difficult, paying attention to a few simple guidelines in the design and maintenance of pneumatic air preparation systems can generate significant savings.
Below Festo provides specific tips on how to reduce your use of compressed air and in turn reduce your energy bill.
Reduce air pressure output from the compressor
Consider reducing supply pressure to the whole machine or introduce pressure zones; each with their own regulator to minimise air consumption and energy usage. e.g. taking an air pressure setting from 6.5 bar to 4.5 bar reduces energy usage by 30%.
Gang mounted regulators reduce assembly costs and keep piping neat and easy for diagnostics and maintenance.
Use pressure boosters where required
If a higher pressure is required for low frequency operations or in only a small part of a machine, use pressure boosters feeding a local reservoir. The hardware costs are quickly recovered.
Stainless steel pressure vessels are safe and maintenance free yet smooth the output to cope with fluctuating demand.
Correctly size air preparation units
Pay attention to the flow rates quoted for air preparation units, oversized filter bowls will not function optimally and won’t remove contaminants from the downstream system. They rely upon inducing a cyclone action upon the air flow, centrifugal force throws the contaminants out of the air, and the optimal function is only achieved when the velocity of the air flow meets the design criteria.
Don’t undersize – but don’t oversize, it wastes money and impairs performance.
Monitor or inspect filter elements
Monitor filter elements and change them before they lose efficiency and effectiveness. Clogged filter elements reduce the flow rate through the air preparation unit and fail to remove particulates. Up to 50% of flow can be lost. Differential pressure gauges or flow meters should be fitted, particularly for fine and micro filter elements.
Stocking and replacing filter elements – a low cost, simple maintenance task that can pay large dividends in filter performance and pressure drop.
Install flow meters
Flow meters allow you to monitor air consumption and changes with the machine on and off, track trends and take remedial action. Flow meters are able to detect leaks far more sensitively then pressure sensors. Even small leaks from loose fittings or a poorly seated filter drain will be detected and quickly pay back the investment cost.
Totalising flow meters flag up leaks and can keep track of total air consumption. Trends can be monitored enabling valuable preventative maintenance.
Check the flow rates of fine filters
Whilst the headline flow rate of the major elements of an air preparation set can meet the application requirements, pay particular attention to fine and micro filter units. To match the grid size of other units the flow rate is frequently compromised. This can lead to a need to run the whole systems at a higher pressure to get the flow rate desired and increase energy use. Fitting take off points before the fine filtration stages for non-critical air quality applications helps optimise the design of the air preparation unit.
Configurable assemblies with matched performance can be delivered fully assembled reducing build time and costs.
Avoid tight bends and constrictions
Consider smooth flow paths at all times. Tight, 90° elbow fittings introduce turbulence and restrictions to air flow. They can drop air flow by up to 30% severely reducing the efficiency of systems.
Selection of the optimum fitting enables laminar flow without turbulence and back pressure.
Use easy to read pressure gauges
Gauges with pre-set operating zones enable fast setting and checking of operating pressures without relying upon skilled technicians. With only a quick glance, operators can check all is well and see that over pressure is as undesirable as under pressure.
The optimum operating pressure can be easily displayed within a green zone. Pressure regulators are adjusted to set the needle within this range.
Avoid water in the system
Condensate drains mounted within or below filter units prevent the carry-over of extracted liquid into the downstream air flow. They range in cost and complexity from fully automatic drains with a float mechanism that automatically vents when the condensate builds up, to semi-automatic drains that vent when the air supply is turned off and manual drains that rely upon regular maintenance inspections.
Float systems vent the extract automatically when the level reaches the pre-set limit.
Use differentiated actuator pressures or single acting cylinders
Often actuators only ‘work’ in one direction. Consider whether a lower pressure can be used for non-working, non- critical working strokes, e.g. for the working stroke extend a cylinder at 5 bar pressure, retract it using only 2.5 bar. Single acting actuators only use air in one direction with a mechanical spring driving the return.
It may be possible and optimum to have a two pressure system for actuators – high for working stroke and lower for idle or return movements.
These simple tips will help you realise significant savings on your energy bills, whilst reducing your compressed air usage considerably. If you would like further assistance, or would like to discuss other options on how to improve efficiency please contact your local ERIKS Service Centre on 0845 006 6000.