Bubble Point Test

The bubble point test is the differential gas pressure at which the first steady stream of gas bubbles is emitted from a wet filter element under specified conditions. The air pressure required to blow the first stream through a pore is inversely proportional to the size of the largest pore in the element.


Dirt Capacity Test

The dirt capacity test determines the weight of a specified artificial contaminant which must be added to the influent to produce a given differential pressure across a filter at a specified condition. It is used as an indication of relative service life.


Multi-pass Test (i.e. ISO 16889)

The multi-pass test is used to determine the Beta Ratio/micron rating and dirt holding capacity of a filter element and is a destructive test.


Patch Test

Visual analysis of a fluid sample. Passing a fluid through a fine media patch. The patch is then analyzed under a microscope.


Crackle Test

A Crackle test is run to determine if an oil sample is contaminated with water.


Portable Particle Counter

A test that takes less than a minute. It generally gives a particle count and cleanliness classification.


Laboratory Analysis

Gives a complete look at a fluid sample. Typical offerings include viscosity, neutralization number, water content, particle count, spectrometric analysis, trending graphs, photomicrograph and recommendation.


Dirt Holding Capacity

The ability of an element to retain dirt or contaminant is referred to as its “Dirt Holding Capacity”. It determines the life of the element and the length of service it will perform before it becomes clogged to the point it must be replaced.


Contaminant Loading

As an element loads with contamination, the differential pressure will increase over time; slowly at first and then very quickly as the element nears it’s maximum life.



Viscosity is the measure of a fluid’s resistance to flow. Fluids that have a high resistance to flow have a high viscosity. Fluids that have a low resistance of flow, have a low viscosity. Fluid viscosity changes with variations in fluid temperatures.


Pressure Drop (Differential Pressure, or Delta P)

A difference in system pressure between the upstream and downstream sides of the filter.
Four Major Factors Contribute to Pressure Drop:

  1. Filter Media
  2. Dirt Contamination
  3. Flows (higher flows create higher pressure drop)
  4. Fluid Viscosity (higher fluid viscosity’s mean higher pressure drop)