Valve takes advantage of paraffin wax to control temperature and flow

March 1, 2018

Valve takes advantage of paraffin wax to control temperature and flowSelf-actuating, thermostatic valve technology helps control temperature and flow in aerospace and defense projects. Currently used in the Patriot missile system, Growler aircraft and other applications, this valve technology is effective in extreme hot or cold temperatures. It is useful in hazardous applications because it operates without the need for external power, and changing pressure does not affect function. Specific uses include freeze protection, scald protection, electronics cooling, mixing and diverting fluids, thermal based permissives and others.

The valves use phase change technology to manage temperature’s effect on flow. The key is a highly refined paraffin wax that changes from a solid to a liquid, or vice versa, at specific temperatures. The temperature at which this wax changes phases is so repeatable and reliable that the ASTM uses it to calibrate temperature instrumentation. ThermOmegaTech® incorporates this substance into its Thermoloid® material, that allow its valves to open and close. For example, when the Thermoloid® material is heated above its melting point it begins to expand and push on the diaphragm, which in turn pushes on a piston. This piston acts as a valve stem, opening or closing a valve.

Then, as the Thermoloid® material cools below its melting point it compresses and a spring returns the piston and diaphragm to its cold position. Because of the gradual transition from solid to liquid of this Thermoloid® material, these valves act more like modulating valves rather than quick opening/closing valves. These direct acting valves are designed to be open when the actuator is in the cold position while reverse acting valves are open in the hot position.

Check out our article in Design World.