Static Franz Cells www.Lab365.co.kr PermeGear vertical glass diffusion cells are classic Franz cells. Standard orifice diameters are 5mm, 7mm, 9mm, 11.28mm, 15mm, 20mm and 25mm, other diameters are custom. The word "orifice" as it refers to a Franz Cell is the area at the top of the receptor chamber that is exposed to the membrane or device through which transport or permeation is being studied...