Heatrex 234 Series

234 Series Washdown/Corrosion Resistant Unit Heater

The Heatrex 234 Series unit heater is the perfect solution to the problem of heating people or equipment in non-hazardous environments where moisture and corrosion exist. Advantages include :

  • Built-in Controls :All necessary safety and temperature controls are included in a single package. Components and motor are factory-wired to a single terminal block for field wiring, eliminating the chance for field error and reducing installation costs.
  • Single Point Electrical Hook-up : Heater, fan motor and controls are all connected to the same branch circuit.
  • Corrosion Resistant : Stainless steel construction, epoxy-coated aluminum fan blade and nonmetallic NEMA 4X terminal enclosure resist corrosion found in sewage treatment plants, swimming pools, car washes, paper mills and marine installations.
  • Washable : This watertight construction can be hosed down without disconnecting the heater, which makes it ideal for coal handling areas, steel mills, foundries, ships, wood finishing plants, cement, sand, grain and food processing facilities.

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233 Series Explosion-Proof Unit Heater

Heatrex 233 Series Explosion-Proof Unit Heater

Heatrex’s 233 Series EXP explosion-proof unit heater is designed with both safety and versatility in mind. Unique 233 Series features include:

  • Industry’s Lowest Ignition Temperature Code Rating : T3C, 320°F (160°C)
  • Dual Over temperature Protection: With both automatic and manual reset over temperature cutouts for additional safety.
  • Nontoxic Propylene Glycol Heat Transfer Fluid
  • Low 70 PSIG Relief Valve Setting: This assures that in an emergency, the initial escaping vapor temperature remains below the 320°F (160°C) ignition temperature.
  • Corrosive Resistant Options: Heatrex offers three constructions suitable for most applications. Standard construction for use in dry non-corrosive areas includes : Welded steel heat exchanger; powder-coated cabinet; epoxy-coated motor. A 316 stainless steel construction suitable for Wastewater Treatment Plants includes : 316 stainless steel heat exchanger, headers and tubes with aluminum fins; stainless steel cabinet; corrosive resistance hardware; epoxy-coated motor. Third construction is suitable for use in Chemical Plants where chlorides are present and includes : Heresite® coated heat exchanger, cabinet, fan blade; corrosion resistance hardware; epoxy-coated motor.

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Heatrex, A One Stop Shop For all Your Heating Needs.

From its beginning in 1959, Heatrex has held the belief that good communication, employee education, attentive customer service and the attitude to excel are the primary ingredients in the manufacture of superior products. Heatrex commits its future to continually provide quality products and performance to its customers.

The engineering team at Heatrex utilizes the latest in CAD systems to provide a timely response to each customer’s needs. Schooled in the “Total Quality” philosophy, Heatrex engineers maintain, and strive to continually improve the design process. Proprietary software removes subjectivity from the design process, providing innovative solutions for design challenges. Drawing and specification control procedures insure that all internal departments, suppliers and subcontractors are continually updated, using the latest customer specifications.

Heatrex understands customer needs; that the accuracy and dependability of a product are crucial to its performance. Heatrex maintains an organization-wide effort to insure product conformance to rigid specifications. Each department carries its own responsibilities in the Continuous Improvement Process, in order to perpetually enhance the production sequence and insure product compliance. Manufacturing parameters are well defined and methodically monitored, assuring cost-effective production and product consistency. Quality is built-in rather than “hoped for” eliminating outdated modes of inspection.

Heatrex maintains quality throughout the manufacturing process starting with inspection of incoming materials from pre-approved suppliers to final inspections of finished products; each critical operation is carefully documented. All documentation travels with the customer order. Testing equipment is kept in compliance with defined specifications, and is independently audited to confirm accuracy, repeatability and reproducibility. First Article inspection is performed to confirm that all specifications have been met.

Final quality audits of product characteristics and in-process control procedures insure that all customer specifications and expectations have been met… resulting in total customer satisfaction.

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Watt Density

Watt Density & Sheath Selection

Watt Density

Watt density is one of the most critical factors affecting element life. Watt density, expressed in watts per square inch of heater surface area, determines the heater operating temperature for a given set of conditions. The sheath temperature of an electric heating element should be limited to provide a reasonable heater life and to avoid possible damage of the medium being heated. We can estimate the sheath temperature or select the appropriate watt density based on the charts and tables provided.

Watt density is calculated as follows:Watt Density = element wattage/3.14 x element diameter (inches) x heated length (inches)

An example is: An 8 kW flange heater has three 0.475” diameter elements with a “B” dimension of 47 inches and a 2 inch cold end. The watt density is: 0.475 x 3.14 x (47 in. – 2 in.) x 3 (# of elements) x 2 (u-bend) = 403 in2 8,000 Watts ÷ 403 in2 = 20 W/in2

Sheath Material

Also critically important, the sheath material must

be suitable for the corrosive conditions and the extreme temperatures of the application. Copper sheathed elements are typically used for low temperature applications such as heating water and some aqueous solutions. Steel is generally used with oil heating applications. Stainless steel and INCOLOY® are used when heating corrosive solutions or high-temperature gas/air. Table I and II list the maximum recommended operating temperatures for common sheath materials.

Watt Density and Sheath Material Selection

Selecting the proper watt density and the proper sheath material is critical to heater life and, if applicable, fluid integrity. If the watt density is too high, the fluid may carbonize, break down chemically, or the elements may burn out. If the watt density is too low the heater price will be high. The greatest heater life will come from the lowest watt density practical for the application.

In general, watt density is determined by three factors:

1) maximum outlet temperature

2) type of fluid heated and

3) fluid flow rate

Sheath material depends on the type of fluid and maximum temperature. If the sheath material selection is incorrect, it will corrode, destroying the element.

Heating Air and Other Gases

Charts A through C give maximum sheath temperatures for a range of watt densities and velocities. This data is based upon air at atmospheric pressure and a 75°F inlet air temperature. For higher inlet temperatures, the sheath temperature will increase accordingly. Contaminants in the air, while normally not affecting the sheath temperature, may require a more highly corrosion-resistant sheath and/or fin material. For heating compressed air and other gases, consult the factory or your local Heatrex representative for watt density and sheath recommendations.


Heatrex is Bringing on a New Industrial Representative – Field Industries

Heatrex is bringing on a new industrial representative, Field Industries out of Houston, TX. Their territory covers the entire state of Louisiana and Oklahoma. Products in their line are:

  • Process air heaters;
  • Circulation and tank heaters;
  • Finned tubular elements;
  • Tubular elements;
  • Direct and indirect immersion heaters and their related controls;
  • Cooling tower control panel and heaters;
  • Impedance heating systems;
  • Bolt and flexible heaters;
  • Infrared heaters;
  • Replacement parts for these products.