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F I R E R O D ® I M M E R S I O N

Compact Unit Gives

Versatility in

Designing a Heating


FIREROD® immersion heaters package up to 300 W/in2 (46.5 W/cm2) in a compact unit, giving you greater versatility

in designing your heating system. This design solution is ideal for replacing large screw-plugimmersion heaters.

Aside from its versatile design, these heaters come complete with a brass 34 (19 mm) NPT double threaded screw plug, which allows you to add conduit boxes. Also, FIREROD immersion heaters are sealed at the lead end with a silicone rubber seal. Solid copper leads, with silicone rubber sleeve, are provided for unconfined wiring. These units are recommended for immersion in water or 90+ percent water soluble solutions.

Performance Capabilities

Maximum operating temperature in water to 100OC (212OF) at 14.7 psi

Maximum watt density to 300 W/in2 (46.5 W/cm2)

Maximum voltage to 480VÅ(ac)


Plastic reclamation

Food preparation

Lab equipment


Resistance Wire



























































































































Oxide Insulation










Double Threaded Brass










34 in. NPT - 138 in. long*


6 in. (150 mm) Solid Pins with Silicone Rubber Boots

*Standard on 58 and34 in. diameter heaters.

Incoloy is a registered trademark of Special Metals Corporation.

© 2005 Watlow Electric Manufacturing Company

Features and Benefits

Nickel-chromiumresistance wire

Precisely centered in the unit assures even, efficient distribution of heat to the sheath

Magnesium oxide insulation

Compacted to the proper density, results in high dielectric strength and contributes to faster heat-up

Incoloy® sheath

Resists corrosion from water

Metallurgically-bondedconductor pins

Ensures atrouble-freeelectrical continuity

Lead end with silicone rubber seal

Protects the heater against moisture contamination

Optional stainless steel fittings

Available for use in corrosive applications

Horizontal through the wall tank mounting

Makes setup faster

240 and 480VÅ(ac)

Provides wiring flexibility

Stock availability

Same day shipment on various 58 in. diameter heaters with34 in. NPT


12001 Lackland Road

St. Louis, Missouri 63146 USA Phone: +1 (314) 878-4600FAX: +1 (314)878-6814Internet:

The small size and big capacity of FIREROD cartridge heating units make them ideal immersion heaters in cramped quarters. When heating liquids of low viscosity, FIRERODs have the high watt density to pack more heat into tight spots. For water heating applications a rating of 150 to 300 W/in2 is recommended. (Laboratory test show that under certain conditions ratings as high as 700 W/in2 are safe.) For longer life at high watt densities:

The FIREROD unit should be in the main body of the liquid and not in a restricted space.

The FIREROD heater should be covered with liquids at all times.

The heater should not be allowed to cycle on and off too frequently.

Scale should not be allowed to form on the sheath.

When heating viscous liquids, such as oils, watt densities must be kept low to prevent carbonization at the heater sheath. FIREROD cartridges offer advantages for heating viscous materials where long life and high quality outweigh the usual economic considerations. As in all immersion applications, scale build-upon the sheath and sludge on the bottom of the tank must be carefully controlled to assure long heater life.

Equipped with smaller threaded fittings than conventional immersion heaters, FIRERODs leave room for more units in the same space. Replacement of single FIREROD units in multiheater assemblies is fast and easy and avoids

discarding the complete assembly.

Moisture resistant seals are available to give protection from damp atmospheres outside the tank.

Built for sustained operation at high temperatures, the FIREROD is especially valuable in heat-transfer

applications with liquid metals. This factor alone has made the FIREROD heater a widely used component in the development of nuclear power systems.

Threaded fittings are furnished in either stainless steel or brass. FIRERODs with Incoloy® or 304 stainless steel sheaths are standard but other sheath materials can be provided. Headers and sheath material should be suited to the material being heated.

Ordering Information

To order stock FIREROD immersion heaters, specify Watlow code number (from Watlow Heater’s catalog) and quantity.

For made-to-order units, please specify:


Overall length

Immersed length

Heated length



Threaded fitting material and size


Stock: Same day shipment

Made-to-Order:Consult Watlow

To be automatically connected to the nearest North American Technical and Sales Office call:


International Technical and Sales Offices: Australia, +61 (39)335-6449China, +86 (21)5211-0231France, +33 (01)3073-2425

Germany, +49 (0)7253-9400-0Italy, +39 (02)458-8841Japan, +81 (03)3518-6630Korea, +82 (02)575-9804Malaysia, +60 (4)641-5977Mexico, +52 (442)217-6235Singapore, +656773-9488Spain, +34 91 675 12 92 •Sweden, +46 31 7014959 •Taiwan, +886 (0)7-288-5168United Kingdom, +44 (0)115-964-0777