S R Options

VOLTAGE OPTIONS

HEATFLEX silicone rubber heaters can be designed to operate from 2 to 600 volts. Because they are resistive elements, HEATFLEX heaters function with either AC or DC voltage sources. Dual voltage heaters are also possible. Dual voltage heaters allow the usage of the same heater for 110 and 220 volt equipment. These heaters incorporate two circuits that are wired in series for the high voltage and parallel for the low voltage. These three lead wire heaters commonly use different colored wires depending on customer preference. Three-phase wye or three-phase delta can be specified for high amperage heaters. For more information please contact Kelvin.

DISTRIBUTED WATTAGE

More effective with etched foil elements, but also possible with wire wound elements, are distributed wattage HEATFLEX heaters. HEATFLEX heaters can be designed to have different watt densities to compensate for edge loss on the outside perimeter of a part or to supply more wattage to a given section of the part. They also can be designed as dual wattage heaters with independent zones. This allows the delivery of more heat for the initial heat-up of the part, but less heat to maintain the part at a given temperature.

THERMOSTATS

HEATFLEX silicone rubber heaters can be supplied with a variety of bi-metallic thermostats to perform different control or safety functions. These thermostats are limited to 240 volts and 15 amps. For controlling or sensing part temperature, HEATFLEX heaters can be manufactured with a hole in them allowing the sensing face of the thermostat to make contact with the part. Indirect sensing of the part can be accomplished by placing the thermostat over a non-heated section of the heater. By placing the thermostat over a heated section, the thermostat will limit the temperature of the heating element itself. This is beneficial as a back-up to the primary temperature controller. For flexible heaters that are used to prevent freezing and condensation build-up in outdoor electronic enclosures, Heatron can mount the thermostat so that the sensing side is exposed to the ambient air in the box.

SENSORS

HEATFLEX silicone heaters can also be supplied with a variety of sensors to send a signal back to a temperature controller. For thermocouples, the standard is 24 gauge stranded type J. Other varieties including K are also be mounted over heated or non-heated sections of the heater depending on the desired results. Most any thermistor or RTD sensor can also be incorporated as part of the HEATFLEX assembly.

HEATFLEX silicone rubber heaters can be supplied with a variety of connecting leads. Standard leads are 200° C, 300volt, Teflon™ (TFE) insulated, 19 strand silver plated copper conductor. For a moisture resistant connection, 18 gauge silicone rubber insulated leads are the best choice. Most all other types of lead wires can be incorporated into silicone rubber heaters. HEATFLEX silicone rubber heaters can also accomodate rubber cords or cordsets (cord with molded plug already attached, usually three or six feet in length). These come in HPN style (also referred to as lamp cord or zip cord) or SJO style. It is also possible to design a heater using three-conductor HPN or SJO. The third conductor is used as a ground that can be left unattached at the heater or be connected to the metal surface. It can also be attached to an internal ground plane built into silicone heater. Another option is to sleeve the leads in silicone coated fiberglass, heat-shrink, or stainless steel overbraid. This can offer the advantages of a clean bundle, additional moisture protection, or added strain relief.

FORMED SILICONE HEATERS

HEATFLEX silicone rubber heaters can be vulcanized to conform to the contours of many different shaped parts. This is particularly useful for heaters that need to fit over columns or pipes. Heatron's silicone rubber heaters can be formed to follow compound curves. Special tooling or forms may be required for this process. For more information contact Kelvin.

THERMAL INSULATION

HEATFLEX silicone heaters can also be supplied with a variety of insulation types on one side. Normally this insulation is 1/8" to 1/2" silicone rubber sponge of a medium density. For applications where the heater and sponge combination will be under pressure. Heatron has access to engineered sponges that resist compression setting.