Description
Understanding Filter Ratings: Absolute vs. Nominal Explained
“Absolute” and “Nominal” refer to different ways of stating the filter’s pore size and efficiency:
Absolute Rating:
– The absolute rating specifies the largest particle size that the filter will allow to pass through 100% of the time.
– For a 0.9 micron absolute rating, this means the filter will remove 100% of particles larger than 0.9 microns.
– No particles larger than the absolute pore size rating can pass through the filter.
Nominal Rating:
– The nominal rating refers to the approximate particle size that the filter can remove with a specified efficiency, usually 85% or higher.
– For a 0.5 micron nominal efficiency of 99.9%, it means the filter removes 99.9% of particles 0.5 microns and larger.
– However, some particles larger than 0.5 microns may still pass through the filter, unlike the absolute rating.
The absolute rating guarantees 100% removal of particles above that size. The nominal rating indicates the approximate size removed at a high but not 100% efficiency.
The 0.9 micron absolute and 0.5 micron 99.9% nominal ratings show the Sterasyl filter has very high particle and microorganism removal capabilities down to the 0.5 micron range.
Brent –
We were pleasantly surprised to find an Australian supplier of this filter at reasonable price. We had two on hand but needed a third. The filter arrived in reasonable time to the remote town where we live and work, and our British Berkefeld gravity filter is back up and running to ensure water from our rain water collection is truly clean for drinking.
Living Whole –
Thank you for your lovely review, Brent! We’re so glad your British Berkefeld system is back up and running and providing clean drinking water for your family. We also really appreciate your support from such a remote part of Australia!