Flexible Heaters

The resistance element is constructed by winding one or more fine nickel alloy wires around a glass string. This type of assembly increases the strength and flexibility of the resistance element and affords great resistance (up to 500 ohms/sq. inch) in a confined area. The winding, which is generally longitudinal, can be brought to within 1/8” of the outside edges. In construction of this type, almost all of the surface of the unit becomes a heating surface. When the heater design permits, several element wires are used in parallel, thus should the unit be damaged, the failure would be confined to a single element, and only a small percentage of the total wattage would be lost.

When the resistance element assembly is completed, it is next laminated between two sheets of glass cloth which have been carefully impregnated with silicone rubber. A special silicone rubber adhesive is used to position the resistance element while under vacuum to expel all air. The sheath is then vulcanized under pressure to form a completely uniform, flexible dielectric sheath. The heaters are next cured at 450°F to remove all vulcanizing agents. The completed Rama-Flex insulating sheath provides outstanding dielectric properties at high temperatures and can withstand severe vibration. The Rama-Flex sheath affords low moisture absorption, resistance to lubricating oils and most chemicals, and will not crack or craze with age. Carefully controlled manufacturing methods insure uniform sheath thickness, maximum dielectric strength and extreme flexibility. Moisture-proof units for immersion applications can be furnished upon request.

Rama-Flex heaters are furnished with 8” Teflon insulated type leads as standard, which meet MIL-W-16878 specifications. Almost any other available lead wire, in most colors is also available upon request. Moisture resistant units are furnished with aircraft-type leads to meet MIL-W-8777 specifications. Lead projection can be placed at any position along the edge of the unit, or at nominal additional cost, they can be placed on the surface of the unit. On standard units, the lead connections are insulated with a small disc of sheath material vulcanized to the heater sheath. Leads are silver soldered to a brass terminal after the sheath has been vulcanized and cured. This allows the use of almost any length and type of lead wire. Lead pull-out strength exceeds 10 lbs. per lead. Rigid terminals are also available upon request.

• the SHEATH or outer covering: fiberglass-reinforced silicone rubber, which is resistant to damage by oils and most chemicals; it will not crack or craze with age.
• the RESISTANCE ELEMENT is interwoven with a glass thread to provide additional strength against breaking. The reissteance element is completed covered on both sides by the fiberglass-reinforced silicone rubber sheath.
• the entire assembly is VULCANIZED to provide a tough, tear – resistant blanket heater, with maximum dielectric strength
• LEADWIRES: 10” Teflon-insulated are standard; other types can be incorporated. Standard leadwires meet the requirements of MIL-W-16878 or MIL-W-8777. Leadwires can exit any edge or surface of the heater.