Tubular Heaters Information
Tubular heaters are used mainly in custom heating applications. They can be formed into various geometries and are designed for either radiant heating or contact surface heating. Often, tubular heaters are immersed in substances such as water, oil, or molten materials. Because they generate heat within the liquid or process, tubular heaters are extremely energy efficient.
Suppliers categorize tubular heaters as single-ended or double-ended. Tubular heaters with round heating elements and flat or triangulated heating elements are also available.
- Single-ended tubular heaters have two terminals at one end.
- Double-ended tubular heaters have one terminal at each end of the tube.
Dimensional considerations included heated length and heated width.
Sleeve/ Sheath Material
Most tubular heaters use a sheath or sleeve as a protective outer covering for the heater elements. There are usually several choices for sheath or sleeve material. Examples include aluminum, brass, copper, fluropolymer, high temperature (HT) foil, iron, nickel alloy, polyimide, rubber, steel, stainless steel, and synthetic rubber.
- Aluminum provides good electrical and thermal conductivity, high reflectivity, and resistance to oxidation.
- Brass is a copper-based alloy that offers good strength, excellent high temperature ductility, reasonable cold ductility, good electrical conductivity, excellent corrosion resistance, and low magnetic permeability.
- Copper is one of the best conductors of heat and electricity.
- Fluoropolymers such as Teflon ® (DuPont Dow Elastomers) are highly-resistant to temperature, chemical reaction, corrosion, and stress-cracking.
- HT foil is usually made of ceramic materials (ceramic foil).
- Stainless steel is a chemical and corrosion resistant alloy that can have relatively high-pressure ratings.
- Tubular heaters may also use synthetic rubber such as neoprene for the sheath or sleeve material.
Tubular heaters differ in terms of features and options. Some products are corrosion resistant, explosion-proof, finned, or portable. Others are suitable for cryogenic use or provide dynamic power regulation. Hazardous location heaters are designed for use in places where there is a risk of fire or explosion. Underwriters Laboratories (UL) and other organizations rate these devices. Indirect fired heaters use a secondary heat exchanger to separate the breathable air stream from the combustion air stream. Features for tubular heaters also include overheat protection, independent timing controls, and internal temperature detectors.