Pegasus is your source for Sabelt Products!
Check us out on Instagram
Your IN STOCK source for quality racing supplies!
Follow us on facebook

In-Line Fluid Filter Micron Ratings and Recommendations

In-Line Fluid Filter Micron Ratings and Recommendations

How Fine a Filter Do I Need?

Fluid filters are typically rated according to the nominal size of the openings in the filter media. Screen filters can also be rated by the mesh size (or "mesh count"). Mesh sizes can be confusing because they refer to the number of openings per inch. A larger mesh number translates to smaller opening sizes.
Mesh Count and Micron Ratings
Mesh Micron Inches Particle Size Filter Example
10 1905 0.075 Sesame seeds Stainless Wire Mesh Screen
  400 0.0157 Coffee grounds Internal Filter for Facet Cylindrical Pumps
60 250 0.0098 Sawdust Setrab 250 Micron In-Fitting Screen
100 149 0.0059 Table salt Setrab Magnetic Inline Screen Filter
  115 0.0045 120 grit sandpaper Fuel Funnel Screen Filter
200 74 0.0029 Silt Facet Fuel Pre-Filters
  40 0.0016 Lower limit of visibility Canton 40 Micron Cleanable Oil Filter Element
  31 0.0012 Pollen Fuel Safe Sock Filter for Fuel Pickups
  8 0.0003 Red blood cells Canton 8 Micron Oil Filters
  5 0.000197 Dust Fram HPGC-1 High-Performance Fuel Filter
  1 0.000039 Bacteria Canton Fuel Filter
Specific Recommendations:

Differential or transmission cooler: 149 to 1270 micron. This filter needs to protect the cooler passages from clogging.

Engine oil pre-filter (inspection filter): 40 to 1270 micron. This filter needs to protect the suction side of the pump from damage.

Engine oil main filter: 8 to 40 micron. Crankshaft journals are often finish-polished using 23 micron abrasives.

Fuel system pre-filter (before the pump): 25 to 400 micron. This filter needs to protect the pump from damage.

Fuel system final filter (after the pump): 1 to 40 micron. High-performance fuel injector manufacturers recommend a 10 micron or finer filter.

General rules of thumb:

For any given size, a coarse filter will flow better than a fine filter. This is why coarse filters are usually recommended for thicker fluids and as pre-filters. Increasing the filter size can (partially) compensate for the lower flow of a finer filter.

In any application, it is hard to go wrong with a coarse pre-filter before the pump with a fine filter after the pump. The fine filter protects the machinery, and the coarse filter protects the pump from damage. The coarse filter will also help to prevent the fine filter from clogging too quickly.

Racing Oil Filters
Racing Fuel Filters

This article was first published on 3/11/2013.

It was most recently modified on 3/26/2015.