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Silicone Rubber Flexible Heaters

Product Overview

Watlow silicone rubber heaters are rugged, yet thin, lightweight and flexible. Use of these heaters is limited only by the imagination. Heat can be put where it is needed. These silicone heaters improve heat transfer, speed warm ups, and decrease wattage requirements.

More Information

With Silicone Rubber Heaters, complex shapes, contours and three-dimensional patterns are possible. Many mounting methods are available for the application of Flexible Heaters.

Silicone Rubber Heaters are rugged, moisture and chemically resistant and are easily bonded or cemented to heat sinks or other parts to be heated. Temperatures from -80 to 390°F (-62 - 200°C) in a wide range of watt densities are regularly supplied. The thin profile transfers heat quickly because the actual resistance element is so close to the heated part. Silicone Rubber Heaters can be insulated with silicone sponge rubber bonded to one side. Another way to lower radiated and convected heat losses is to apply an aluminized foil surface to the heater back.

Applications

Antenna
Farm Animal Feeders
Photocopy Equipment
Hydraulic Equipment
Photography Developing
Food Service Equipment
Oil Pumps and Reservoirs
Electric Motor Dehumidifying
Packaging Equipment
Autoclaves
Freeze Protection for Drains in Refrigeration Equipment

Optical Equipment
Aircraft Air Intake
Glue and Laminate Curing
Aerospace Composite Bonding
Gyroscopes
Vending Equipment
Presses
Heat Sealing
Automobiles and Other Vehicles
Outdoor Electrical and Electronic Enclosures

Spacecraft
Laser Printers
Consumer Appliances
Battery Heating
Floor Processing Equipment
De-icing and Anti-icing Equipment
Aircraft Gallery Equipment
Dispensing Equipment
Vacuum Chambers
Medical, Laboratory, and Veterinary Equipment

Resistance Element

The resistance element in Flexible Heaters is either wire wound or etched foil.

Wire Wound Element
A fine gauge resistance wire is spiraled around a fiberglass core. The element is placed in a specifically designed pattern and vulcanized to either a silicone rubber or neoprene substrate. Advantages versus etched foil elements are: Physical strength; flexibility; smaller production quantity; conforms well to small radius bends and larger possible sizes.

Etched Foil Element
The manufacturing process of etched foil elements is adapted from the production of printed circuit boards. A nickel resistance alloy foil is acid etched to the specific pattern, then vulcanized to the sheath material. Advantages versus wire wound are: Higher watt densities; greater area coverage of element over heater sheath; higher production quantities and complex heat distribution.

Termination

Silicone leads for temperatures to 390°F (200°C) are most often supplied, but many other types are available. The leads are attached to the element within the transition area and covered with a patch of the same material as the sheath.

The entire lead transition assembly is then vulcanized to the heater sheath. Leads can be arranged to exit at about any point on the element sheath, corner, or from an external tab. Neoprene, silicone and Teflon leads along with SJ and HPN cord and plug sets can be supplied.

Silicone Rubber leads are standard unless otherwise specified. Teflon leads are also available. 14, 16, 20 or 24 gauges are sized by requirement. Maximum lead length is 72". Available with Patch and Strain Relief Tab.

Patch
Lead patch can be placed along the heater edge at the following positions:

CW - Center of width
UW - Upper corner of width
LW - Lower corner of width

Standard patch dimensions vary by heater size and design.

Strain Relief Tab
Standard tab dimensions: 2" long x 2-1/2" wide. Can be placed in CW, UW or LW position. Minimum width: 2-1/2"

2 Conductor SJ type 16/2 Cord
with 2-3/4" Round Termination Cap is often specified. Max temp is 140°F. NEMA1-15P Plug is available for 120 volt items.

3 Conductor SJ type 16/3 Cord
with Round Termination Cap is also available. Ring terminal is attached to ground wire. Max temp is 140°F. NEMA1-15P Plug is available for 120 volt items.

Mounting Methods

Pressure Sensitive Adhesive (PSA) is a factory applied material for bonding Flexible Heaters to a flat, smooth surface. A peel-away protective backing allows simple field installation. The maximum element temperature for PSA use is 300°F (150°C) continuous, at no more than 5 watts per square inch. Heaters with PSA should be stored no more than 6 months before installation.

Factory Vulcanizing provides excellent heat transfer from the heater element to the customer part. Strong, free of air gaps and with the longest possible heater life are advantages of Factory Vulcanizing.

For field applied adhesives, an RTV Room Temperature Vulcanizing Adhesive or Contact Cement are available. Consult Ogden.

Also available for Flexible Heaters are several mechanical field mounting devices such as hooks and laces, grommets and laces, spring loaded latches, snaps or velcro.

Thermostats and Sensors

Thermostats are typically integral to the heater, encapsulated in silicone rubber and mounted in a heated area. The position is determined based upon application considerations, prototyping and testing.

Thermostats separate from heater and ambient sensing thermostats in several temperature ranges are also available.

Thermocouples, RTD's, thermistors and thermal fuses are normally mounted under a silicone rubber cap which is vulcanized to the heater sheath. The position can be anywhere on the heater surface.

All items rated 125V/15A, 250V/10A.

Thermostat can be wired separately when rating is exceeded. Typically, the differential between the on and off position is 30°F.

Open	Close	Open	Close

55°F	40°F	160°F	130°F
(ambient sensing only)		170°F	140°F
80°F	50°F	180°F	1150°F
100°F	70°F	190°F	160°F
110°F	80°F	200°F	170°F
120°F	90°F	250°F	220°F
130°F	100°F	300°F	270°F
140°F	110°F	392°F	365°F
150°F	120°F	(hi-limit only)

Specifications

	Wire Wound	Etched Foil

Maximum Width	36" (915mmm)	12' (305mm)
Maximum Length	120" (3050mm)	30" (760mm)
Thickness	0.055" (1.4mm)	0.031" (.64mm)
Resistance Tolerance	-5 +10%	-5 + 10%
Wattage Tolerance	-10 +5%	-10 +5%
Minimum Ambient Temp.	-80 Deg F (-26C)	-80 Deg F (-62C)
Maximum Operation Temp.	390 Deg F (200C)	390 Deg F (200C)
Maximum Voltage	600V	600V

Thickness of Optional Silicone Sponge Insulation:

1/8", 1/4", or 1/2"

Thickness of Optional Foil Backing:

0.005" (0.13mm).

The area where leads are attached adds additional thickness depending upon gauge wire used and type. Consult Ogden.

Dimension Tolerances:

Less than 6" (150mm); ±.03" (± .8mm)
6 - 12" (150mm - 305mm); ±.06" (±1.5mm)
12 - 36" (305mm - 915mm); ±.12" (±3.5mm)
Over 36" (915mm); ±1%

12" leads are standard. Gauge of wire to be determined based on amperage or other considerations.

Composite Bonding Processes and other applications may require special heat pattern or uniformity. Heat Mapping Certification is available as an option. Underwriter's Laboratory and CSA recognition or listing apply to most configurations.

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