In a compressed air system it refers to the excess consumption of compressed air caused by operating the system at a higher pressure than necessary for the actual air requirements of the equipment. Generally, it is a hidden problem caused by unregulated uses, point of use with regulators adjusted to their maximum setting.
As the supply pressure fluctuates, artificial demand changes from a minimum to a maximum waste level. When real production demand decreases and system pressure rises, artificial demand increases. Eliminating leaks causes the system pressure to rise and all unregulated demand increases in proportion to the pressure rise. Sometimes, operators increase the end use point pressure to perceived improvement in equipment performance. When an operator can no longer elevate the pressure, the supply pressure limit of the system has been reached. Beyond this, the compressor pressure may also be increased. At this point, the application follows the supply pressure.
The higher pressure causes more volume to flow through orifices, leaks, exhaust ports of pneumatic actuators, or similar types of openings. This means that the system is always running as though it needs to provide pressurized air throughout the system, even if the actual demand isn’t there. For example, a 20 PSI increase on a ¼ pipe will cause 10 more volume of air to flow out the opening.
Below chart indicates how the air flow increases and decreases corresponding to the air pressure.
Impacts of artificial demand:
- Increased energy use: compressors consume more energy to produce air at higher pressures, which is wasteful when the equipment doesn’t need that level of pressure to operate effectively.
- Higher leakage rates: Higher pressures increase leaks throughout the compressed air system, causing more air (and thus more energy) to be wasted. Compressors must supply air to meet the (Total Demand = Real Demand + Artificial Demand), which could be an increase of 20% to 25% causing increased energy consumption.
- Reduced equipment lifespan: Operating tools and equipment at higher than required pressures can lead to more frequent maintenance issues and shorter lifespans for the equipment.
- System capacity issues: By consuming more air than necessary, artificial demand can also give a false impression that more compressor capacity is needed, potentially leading to unnecessary capital expenditure on additional compressors.
