What allows for retrofit without large pressure increases in the system?

The ability to retrofit a system without experiencing significant pressure increases is primarily facilitated by the concept of particles bypassing cells. When air filtration systems are designed, there can be instances where the airflow may not be fully captured by the filters, especially if the filters have a very high level of efficiency or if they become too restrictive.

In such cases, if particulates can bypass the filtering cells through gaps or less dense areas, it allows for better airflow overall within the system. This results in a lower static pressure drop, meaning the system operates more efficiently without needing to exert additional energy or increase the setup's pressure.

Using high-efficiency filters can sometimes lead to excessive pressure drops, complicating the retrofit process. Similarly, humidity control systems and static pressure adjustments may impact system performance but do not specifically address the manner in which particles can bypass filtration without causing additional resistance in the system. Thus, the concept of particles bypassing cells is crucial for maintaining efficient operation during retrofitting.