90 Feet per minute average face velocity is the most common air flow specification in HEPA/ULPA filtered environments. However for some applications where a large volume is required out of a relatively small filter face flows as high as 180 FPM may be specified. And conversely in mini-environments and Semiconductor Equipment Front Ends, flows as low as 70 FPM are common. If you are not sure what flow to specify, please feel free to contact TES-Clean Air Systems for assistance. Our FFUs are typically designed to be able to produce 20% more flow than what is specified, to allow for eventual filter loading.