Mainly for delivering liquid or gas to a device inside a vacuum chamber, often to maintain the device’s temperature or to actuate a pneumatic mechanism.   Occasionally, liquid-gas FT connects to internal devices that are not electrically grounded.  For these applications, use electrically isolated power FT with tube conductors.

Cryogenic FT is similar to gas-liquid FT except for a long thermal path between tube and flange. Heat transfer is reduced and hence cryogenic evaporation rate.