Air filter medium, filter pack, and air filter unit

Abstract

There are provided an air filter medium, a filter pack, and an air filter unit in which the decrease in collection efficiency can be suppressed. The air filter medium includes a fluororesin. The PAO permeability ratio (final permeability/initial permeability) is less than 3.0. The initial permeability is a permeability of polyalphaolefin particles when air containing the polyalphaolefin particles having a number median diameter of 0.25 μm is passed through the air filter medium at a flow velocity of 5.3 cm/s. The final permeability is a permeability of polyalphaolefin particles when air containing the polyalphaolefin particles having a number median diameter of 0.25 μm is continuously passed through the air filter medium at a flow velocity of 5.3 cm/s and the pressure loss is increased by 250 Pa.

Dependencies are inferred from the claim text.