Filtration is the process by which solid materials (commonly referred to as particles or particulates) are captured or removed from either air, gas, liquid or solid mixtures. By adding a medium, or media, for the mixture to pass through, the unwanted particulates are filtered or separated out, leaving a solid reduced mixture that meets the purification requirements for the particular application. Particles that are filtered out of the mixture are dependent upon the micron rating of the filter cartridge, element or system utilized during the separation process, and based on the use of a Nominal or Absolute micron rated filter.
Definition of Filtration: The act or process of capturing or removing an unwanted particulate from an air, gas, liquid or solids (of varying particle sizes) using a filter or sieve (sifter / strainer).
Definition of Pleated Filter: Pleated filters are manufactured with various medias / materials that are crimped into pleats (accordion folds) that provide a barrier to capture , or filter out, unwanted particulates from air, gas, liquid of solid mixtures.
Key Filtration Terms:
Differential Pressure (DP):
The measurement between the input pressure (PSI – Pounds per Square Inch) going into the filtration device (Housing, Canister, Vessel, etc.) and the pressure being measured on the filters output flange / port. The difference between the filter’s input and output increases as the element / cartridge captures particles from the mixture being filtered. Ideally you should measure little to no initial differential pressure (DP) indicating that the filter element / cartridge itself, when newly installed, is flowing freely and not adding unnecessary flow restriction and loading the pump before the filtration system even gets starting collecting particulates. Maintenance personnel use differential pressure (DP) measurements, generally supplied by the manufacturer or company engineering department, to determine ideal times to replace filter elements / cartridges.
As solid particles are captured from a suspension they collect into a cake form. A filter cake is created when the particulates that are filtered begin to build up. The filter cake expands over the life cycle of the filter element / cartridge being used in the filtration system and continues to grow thicker as particles continue collecting. As the particulates continue to build up the flow pressure (DP – Differential Pressure) beings to increase PSI. Utilizing manufacturer suggested flow rates & pressure differentials you can determine when the filter cartridge / element requires changing, or in certain filtration systems you can backflush to clean out the filter for further use. In excess of manufacturer’s suggested flow rates & pressure differentials could result in catastrophic failure to the filter element/cartridge or the filter housing, and creates a hazard of flying projectiles should the housing rupture. On the lighter side of this caution, operating beyond manufacturer suggested ratings diminishes the flow rate and particulate capture rate, basically decreasing your filtration efficiency.
Filtration ratings are generally based on the smallest micron (µm) size of the particle (particulate) to be captured (filtered out). A micron is equivalent to one millionth of a one meter, which is so small it isn’t visible with the naked eye. The visibility threshold is approximately 40 microns (.0016”… between 1 & 2 thousandths of one inch), or for comparison’s sake, a typical human hair if approx. 70 micron (between 2 & 3 thousandths of one inch). Just a few more comparable:
> Bacteria = 2 microns
> Talcum Powder = 10 microns
> Pollen = 60 microns
> Salt = 100 microns
> 1 micron = .0000394 inches (or 12,000 US Mesh)
> 25,400 microns = 1 inch
> 1,000 microns = 1 millimeter (or 18 US Mesh)
Copyright © 2017 | Filtration Products