About Project

Why perform filter media analysis?

Filter analysis is performed for many reasons, including failure analysis, trouble shooting system operations, or for a routine checkup to determine the remaining life of the filter. Comparisons with competitive materials and guarantee issues are additional reasons for filter analysis.

What are the modes of failure?

Typically, there are five modes of failure to consider when analyzing filter media. These modes are mechanical strength/ wear, chemical degradation, thermal degradation, dust penetration/media blinding, and incorrect design. They address performance of the filter against material, product, and application design specifications.

What tests can be done to and assess the condition of the filter?

To fully address the five failure modes, an evaluation of the filter condition and properties should be performed. These evaluations take place by sampling the used filter and performing an array of specific tests. Sampling of an unused filter is also recommended to establish a benchmark for comparison.

Inspection of the failure at the site of operation is preferred, but when inconvenient, a laboratory analysis must suffice.

Visual analysis during this inspection often reveals the most useful information.

The pieces of the puzzle that must be assembled include permeability, material strength, visual/microscopic analysis, particulate capture efficiency, system performance data, temperature of the gas stream, and the properties of the dust being collected.

Permeability Testing:

Permeability, as defined by the Frazier Number, is the volumetric flow rate, measured in cubic feet per minute (cfm), through a square foot of filter media at a pressure differential of 0.5” water gauge (w.g.). The unit of measure is written as cfm/ft2 @ 0.5” w.g.

Mullen Burst Strength Test:

The Mullen Burst Strength Test is a measure of the two-dimensional, or planar, strength of the media, measured in pounds per square inch.

Tensile Strength Test:

The Tensile Strength Test is a measure of the directional strength of the media, measured in pounds per square inch.

Microscopy:

Visual analysis of a filter sample is often aided by the use of a light microscope.

Efficiency:

Particulate capture efficiency is an additional test that results in a filter performance characteristic.