Is a "Pinhole" a Serious Problem in an Air Filter Media?

Sep 10, 2015

Do you know "Pinhole"?  "Pinhole" can easily happen to a filter media during manufacturing or converting processes.    

Microglass fiber media are fragile. A shot making a pinhole or pinholes in the fabrics can frequently occur in electrospinning and in meltblowing (MB) processes. How seriously will apinhole affect the filtration efficiency (FE) of a filter media?

In air filtration of a fibrous material, particles are captured on the fiber surface by mechanical mechanisms such as inertial impaction, direct interception, and Brownian diffusion, as well as by electrostatic attraction for an electret media. Particles in the aerosol pass through the pinhole without being captured by the fibers.

Assume that the cross section of pinholes is circular, the fluid flow rate through a circular pipe is calculated by Hagen-Poiseuille law, in which the flow rate is proportional to the fourth power of the pipe diameter and linearly proportional to the pressure drop across the media. This law was employed to calculate the aerosol flow rate and then to calculate the penetration through a pinhole of a filter media in this article.