Etched Foil Silicone Rubber Heater Specifications:
- Sizes: Custom, contact Durex Industries to discuss your application
- Standard Thicknesses: .030“ or .043”
- Maximum Operating Temperature: 450°F (230°C)
- Minimum Operating Temperature: -60°F (-50°C)
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- Standard Dimensional Tolerances: Less than 12” ± .062 , Greater than 12” ± .125
- Maximum Watt Density: 60 W/in² (depending on application, consult Durex for higher densities)
- Maximum Voltage: 600 volts
- Wattage Tolerance: ±10% standard
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Wire Wound Silicone Rubber Heater Specifications:
- Sizes: Custom, contact Durex Industries to discuss your application
- Standard Thicknesses: .030”, .043“, or .056”
- Maximum Operating Temp: 450°F (260°C) intermittent
- Minimum Operating Temperature: -60°F (-50°C)
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- Standard Dimensional Tolerances: Less than 12” ± .062, Greater than 12” ± .125
- Maximum Watt Density: 5 watts/in² (depending on application, consult Durex for higher densities)
- Maximum Voltage: 600 volts
- Wattage Tolerance: ±10% standard
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Silicone Rubber Heater Mounting Options:
Vulcanizing:
Silicone rubber heaters are most effectively attached to factory surface parts through vulcanization. Using a heat and pressure process, Durex Industries’ silicone rubber heaters can be bonded to a metal surface with no adhesive. The resulting bond is not only strong, but it also allows excellent heat transfer. This method permits higher watt densities and temperatures than other methods while still operating safely.
Mechanical Bonding:
If heaters need to be removable, mechanical bonding options may be ideal. These include lacing eyelets, spring and eyelet combinations, boot hooks, boot type fasteners, snaps, and hook and loop Velcro type fabric straps. Clamps can also be used. The surface must be free of dirt and any chemicals that might harm the silicone. The surface should also be examined for sharp protrusions that could pierce the heater. Insulation can be used to direct heat towards the surface and cushion the heater during compression.
Pressure Sensitive Adhesive:
Silicone rubber heaters can also be applied with a pressure sensitive adhesive. First, ensure that the heater is being applied to a clean surface. The heater should then be rolled in place to eliminate any air bubbles that would compromise the bond. Large, heavy heaters may not effectively bond with PSA as their weight can pull them off the surface as temperatures rise. PSA does have a limited shelf life.
Silicone RTV:
Silicone RTV is a liquid silicone adhesive that can be used to bond silicone rubber heaters to a surface. It is important that the surface is clean and free from any bumps or grooves to ensure an even bond. Without an even bond, heat cannot be evenly transferred and overheating can occur. RTV cures at room temperature and requires humidity to cure properly. To guarantee moisture, place a humidifier near the heater or a moist towel over it if the environment is dry.
Additional Options:
Temperature Controls
One way of providing temperature control of surface heaters is a built-in thermostat. Wired to the heater, the thermostat can be mounted over a heated section to sense the heater’s temperature or over a cold section to indirectly sense the temperature of the part. When mounted over a cold section, the thermostat avoids limiting the temperature of the heating element. Thermostats can be preset with a wide variety of ranges. Silicone Rubber heaters can also feature a thermal switch or an adjustable thermostat. If chosen, the temperature should be increased slowly over time to determine the proper thermostat setting.
Sensors
Other temperature control options include thermocouples, RTD’s, and thermistors. Multiple thermocouple types are available and can be mounted over heated or cold sections. Specify when ordering. RTD’s provide accuracy and stability since their resistance increases as the temperature of the heater rises. Thermistors are also resistance-based, but are ideal for limited temperature ranges or a specific single temperature.