Ending Improper use of Compressed Air
There is a common misconception that compressed air is free and always safe. Because it is air people do not associate it with cost, and because it is not directly connected to a power source, they do not consider the potential dangers. Compressed air is readily available, simple to use, and is often used in situations where a more economical, and safer, energy source or tool could be used.
Compressed air is the most expensive form of energy available on the planet. It takes 8 hp of electricity to produce 1 hp of compressed air. According to XENERGY, Inc. prepared for the Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory, compressed air systems account for 10% of all electricity and approximately 16% of all motor system energy use in U.S. manufacturing industries; and can account for even more if used improperly.
According to the U.S. Department of Energy, approximately 80% of compressed air energy use is lost as heat, and approximately half of the remaining air is used for work. The rest is wasted through leaks, artificial demand, and improper use. Common misuses include:
- Open Blowing – The use of compressed air with an open, unregulated tube or pipe
- Sparging – Aerating, agitating, oxygenating, or percolating liquid using compressed air
- Cabinet Cooling – Creating A/C from the compressed air supply
- Vacuum Generation – Compressed air is used to create negative-pressure mass flow
- Atomizing – The use of compressed air to disperse a liquid as an aerosol
- Padding – The use of compressed air to transport light solids and liquids
- Max Compressor Size – Running a compressor that is larger than the plant needs
- Maximum Pressure – Maintaining pressure higher than it needs to be
- Abandoned Equipment – Supplying air to equipment abandoned after process change
- Unregulated End Use – System operating without a regulator to limit end use pressure
Improper Use a Safety Concern
Using compressed air to clean dirt and debris from a workplace is not only a costly waste of energy, it is an unsafe practice that could result in serious injury. The high pressure air has the potential to make particulate enter the eyes, ears, or penetrate the skin. It can also create fine airborne particles that are hazardous to inhale. The OSHA regulations state it should never be used for cleaning purposes, except where pressure has been reduced to less than 30 psi, and then only with effective chip guarding, and personal protective equipment.
Compressed air is often used to dust off clothing and has caused serious and even fatal injuries. Air pressure as low as 5 to 10 psi has been known to cause serious injury. It can enter the blood stream if directed at an open wound, and can lead to an air embolism, or bubble in the vein which can lead to blockage. If the embolism travels to the heart it can have symptoms similar to that of a heart attack, and can cause a stroke if it reaches the brain. The air typically contains small amounts of oil or dirt, depending on the air treatment level, which can also lead to infection as the air enters the body.
Alternative Energy Uses
According to the U.S. Department of Energy’s Compressed Air Challenge, compressed air should only be used if it will result in significant productivity gain, labor reductions, or safety enhancements. Alternative energy sources can be used to complete the majority of the listed tasks in a more economical way. This Challenge suggests the following alternatives to safely complete tasks in more energy efficient ways:
- Use blowers to provide cooling, aspirating, agitating, mixing, or to inflate packaging.
- Use spring loaded triggers or auto valves to reduce unnecessary air consumption on air lances and air guns
- Use air conditioning or fans to cool electrical cabinets instead of compressed air
- Use brushes, blowers, or a vacuum system to clean work space
- Use blowers, electric actuators, or hydraulics to move system components
- Use low pressure air for blow guns, air lances, and agitation
- The amount of air should be at the minimum quantity and pressure for an application
- Stop air flow to unused equipment as far back on the distribution line as possible
- Use a pressure regulator to limit the maximum end use pressure
By focusing on eliminating improper use of compressed air you can significantly reduce the amount energy used, save money on utility costs, and improve safety.