HEPA air filters are designed to create flow resistance and generate a large pressure drop across the filter. In our tests, most HEPA Smart Air filters have a pressure drop of between 50 and 200 Pa, depending on air flow, air duct, and filter obstruction. This can be used as a rough guide for finding and sizing a fan. Most publications from HEPA air filter manufacturers recommend replacing the filter when the resistance due to dust load is 2 inches per week. The final pressure drop of a filter will usually be 1 WC or 1.5 WC, but it can vary depending on the filter and the application.
The initial pressure drop of a filter will also differ based on the type, thickness and efficiency of the filter. As a filter is used, it accumulates particles and, gradually, it becomes more difficult for air to pass through it. The pressure drop caused by the filter increases. Using a filter that surpasses its final pressure drop will reduce hardware performance and force the fan to work harder to expel the same amount of air through the system. This can increase the risk of costly hardware failure.
It is essential to understand how much pressure drop a HEPA filter can create in order to guarantee that your system is running efficiently and safely.
