One way that dental compressor designers have found ways to squeeze increased efficiency out of air compressors is by creating models that operate at variable speeds. In other models, compressors typically operate in modulation mode. While this is an efficient approach to pressure delivery to end-use tools, it’s very inefficient when it comes to energy consumption. Even if a compressor in modulation mode is only delivering 20% of its pressure capacity to end-use applications, it’s still consuming 70% of its maximum load power.
Luckily, compressor manufacturers have addressed this problem by introducing new, more efficiently operating modes. The first is often referred to as load/unload mode. This mode uses stored air to maintain air pressure while the main compressor blows excess pressure. This unloading period drastically reduces power consumption, to somewhere between 10 to 25% of the power consumed during the load period. However, these systems are only as efficient as the system storage capacity. The longer a compressor system can operate in unload mode, the lower the power consumption. If the system must return to load mode too quickly in order to meet end-use demands, energy savings will be minimal.
Variable Speed Control compressors have a more direct relationship between end-use pressure requirements and power consumption. Because these systems are capable of only producing and delivering the exact amount of pressure required throughout the system at any given time, they are great for operations that do not need maximum pressure for the majority of the time. However, they are less efficient than traditional compressors when at full-capacity, so they aren’t always the best option for systems that tend to operate at maximum for most of the day.
Variable Displacement Control compressors adjust the maximum capacity of the compressor according to end-use requirements. If you use 50% of your compressor’s maximum capacity for the majority of the day, this type of control effectively reduces the size of the compressor during that time accordingly. However, just like those with Variable Speed Control, these systems are less efficient at maximum capacity, and thus should only be considered if your operation includes a lot of variation in end-use pressure requirements.
Depending on the size of your compressor, some older models can be retrofitted to include these new controls — Variable Speed Controls retrofits are especially common. However, these can be costly and thus should only be considered for large compressors that would be especially expensive to replace. For smaller operations, a complete replacement is generally the most cost-effective option.