Glossary – F

Factory Mutual Approval (FM Approved): Independent testing performed by the insurance carrier FM Global. FM Approval uses scientific research and testing to make sure products conform to specific standards for safety and property loss prevention.


Fahrenheit: A temperature scale which is based on 32° as the freezing point of water and 212° as the boiling point of water when the water is pure and at 14.696 psi absolute pressure.


Filter: A semi-transparent material that attenuates certain wavelengths of radiation.


Flash Point: The lowest temperature at which there is enough vapor evolution from the surface of the
material being tested to make a small flash when a small bead of flame is passed over the material.


Flashing: Thin pieces of impervious material, usually aluminum or galvanized steel, installed to prevent the passage of water into a structure from a joint or as part of a weather resistant barrier system.


Frequency: The number of cycles that occur in 1 second (cycles/second). The unit of measure is the hertz (Hz).


Fuse: An overcurrent device that operates on rise in temperature. The fuse link melts and removes the power source from the load.