3D Formed Silicone Rubber Heater for Aerospace Application
July 22, 2020
Components such as water pipes and valves designed for aerospace applications often face many unique challenges. One of the main challenges is high altitude operation with ambient temperatures around -50°F. Heating of these components is almost always necessary to avoid icing and ensure pumps work seamlessly without disruption in flow. Any buildup of ice within pipes at such a high altitude and low temperature could be catastrophic.
A customer facing this exact issue approached Tempco. This company, who supplies the aerospace industry with parts and accessories, was in need of a heating solution for a motorized water valve. This water valve was located in an unpressurized and unheated portion of the aircraft. Piping before and after the valve was heated but heat also needed to be applied to the valve itself. This would ensure no icing would occur as the liquid passed through the valve body. The geometry of the valve body was small and intricate. Tempco knew that the only way to effectively apply heat was to design a three dimensional (3D) formed silicone rubber heater.
The final solution consisted of a silicone rubber heater formed to a cube shape. The heater was designed to receive power from a 28V control box in the undercarriage of the aircraft. It operates at approximately 2wpsi for this freeze prevention application. Some additional design features include:
- Holes are present on three of the heater’s faces to allow the fittings on the valve to run through the heater.
- Thermal insulation covering the heater to protect the back side from excessive heat and help direct most of the heat towards the valve body.
- A snap action, heater sense thermostat with open/close setpoints was incorporated onto the heater body, allowing more precise control and preventing overheating of the valve.
- The thermostat setpoints of 70°F/40°F keeps the heater operation temperature above the freezing point of water, preventing any ice buildup within the valve body.
- A custom mold was developed for the thermostat due to its unique size and cutouts were included in the sponge to help precisely fit the mold.
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