Band Heaters Information
Band heaters are ring-shaped heating devices that clamp around a cylindrical element. Heat transfer from band heaters occurs via the conductive method. Most band heaters clamp around the outer diameter of a cylindrical element and heat the element from the outside. Some products clamp around the inner diameter of a pipe. Typically, band heaters are quipped with ceramic or mineral insulation to reduce heat loss to the environment.
Selecting band heaters requires an analysis of performance specifications and features. Parameters to consider include: maximum operating or sheath temperature, AC voltage required, and watts.
Maximum operating temperature is the maximum temperature that the sheath covering the heater may reach. Note that maximum sheath temperature is not the maximum temperature that a heated substance may reach.
AC voltage required is the minimum alternating current (AC) voltage required for band heater operation.
Important dimensions to consider for band heaters include the inside diameter, width, and thickness of the band. As a rule, the inside diameter of a band heater should be the same size as the outside diameter of the cylinder to be heated.
Band heaters use a sleeve, jacket or sheath as a protective outer covering for the heating elements. Choices for sleeve material are aluminum, brass, copper, iron, nickel alloy, steel, and stainless steel.
Typically, insulation is used to reduce heat loss to the environment. Choices include: no insulation, ceramic insulation, mica insulation, mineral insulation, and fiberglass insulation. Products with more than one type of insulation are commonly available.
An uninsulated band heater has a lower profile and is useful in areas where space is at a premium; however, an uninsulated band heater is not particularly energy efficient.
Band heaters that are equipped with a layer of ceramic insulation can resist both heat and chemicals. Ceramics are made of nonmetallic minerals, such as clay, that are permanently hardened by high-temperature firing.
Mica is valued for its electrical insulating properties and high resistance to heat and acids.
Features for band heaters are cooling options, probe holes or cutouts on the band, insulated shrouds, and expandable heaters.
Band heaters must attach, or clamp to the object(s) they are heating. Most have multiple clamping options from which to choose. Examples include: standard (bent up) flange or tab, quick release, built-in strap, separate straps, barrel nuts and wedge lock or mounts.
Termination type refers to the method used to make electrical connections to the heater. Some band heaters have multiple options for the termination type. Terminal types for band heaters include: insulated leads, armor cable leads, metal braided leads, flexible conduit leads, tandem screw terminals, parallel screw terminals, terminal boxes, and quick disconnects.
Image Credit: OMEGA