Pressure drop

RAM_Fan_Chart

Ventilation Advice – Pressure Drop

The airflow capacity of a fan is commonly measured in metres cubed per hour (m3/hr). Pressure within the ventilation system has a direct effect on the flow rate of a fan, so all fans will have a pressure loss curve contained somewhere in the literature that is supplied with the fan.
Pressure is measured in pascals (Pa) and in all cases a fan’s maximum flow rate is measured at 0 Pa. Adding ducting and/or a filter to a ventilation system will increase the operating pressure and as such will lower the flow rate of the fan. It is critical that you understand this in order to specify the correct filter for your area.
As a rule of thumb, when you purchase your filter, make sure its cubic metre capacity is 20% greater than the fan output. This will assure you have the best filtration efficiency.