Copper/water heat pipes are made of copper, use water as a working fluid and typically operate in the temperature range of 20 to 150°C. ACT manufactures copper/water heat pipes into two basic geometries: Tubular Heat Pipes and Planar Heat Pipes. The tubular heat pipes typically have outer diameters from 1/16″ (1.5mm) to 1.5″ (38mm). Custom diameters can be manufactured per customer requirements. The planar heat pipes are also called vapor chambers which are used as heat spreaders. Copper/water heat pipes can be combined with other components to form heat transfer assemblies.