Filtration Guide


Many Gems Sensors products have recommended filtration. The purpose is to protect the internal components, maintain extended product life, prevent sticking, and help ensure sensor accuracy.

One way filtration is measured is in microns. Micron is short for the measure of length called a micrometer which is one millionth of a meter (appx one twenty-five thousandth of an inch). It is actually used to describe the size of very small particles.


The example above shows a rough representation comparing common micron sizes recommended by Gems for some of their flow products. The 70 micron size, included for reference, is an average diameter of human hair, and 50 microns is generally accepted as the smallest micron size visible to the naked eye. 50, 100, and 150 microns are the three sizes Gems specifies when choosing the correct filter for your application. These specifications are required due to the small orifices and pathways your fluid (both liquids and gases) must pass through. Small moving parts also benefit from proper filtration to allow for obstruction free operation and protection from the build-up of contamination or sediment.


All of Gems turbine flow sensors (FT series) are rated at 50 microns. All shuttle type flow switches are rated at 150 microns. Here is the list of flow products and their recommended filtration:

 50 Micron  100 Micron  150 Micron

FT-110, FT-210, FT-330, FS-4,

FS-925, FS-926, FS-927,

FS-10798, FS-930
 FS-380, FS-480


FS-150, FS-200, FS-400, FS-500



Even though the filter size is not directly specified for Gems valves, the orifice size is documented for each valve model. This allows you to choose a filter smaller than the orifice to protect the components and prevent openings from being clogged. For example, the AG2001 series valve has a body orifice size of 0.79mm. Using 500 micron filtration would filter out particles bigger than 0.50mm reducing the risk of clogging. It is important to review the application and all factors for proper filtering as a smaller micron rating may be required.

Another measurement for filter size is mesh. Mesh size refers to the number of openings in one linear inch. Mesh is primarily used for larger screen filtering starting at 35 mesh (500 microns), although larger mesh sizes (more/smaller openings) are offered.

It is ultimately the responsibility of the user to determine best filtration practices based on the specific application and many other factors that can affect fluid quality. When properly fitted, the appropriate filtration can offer protection, longevity, and accuracy for your products and equipment.

See our flow and valve troubleshooting & technical content here