Explosion proof heaters are constructed with housings that can withstand explosions, sparking and flames during the heating of materials. Most devices include a protective sheath that covers the heating element. There are several basic types of explosion proof heaters. Cartridge heaters are cylindrical devices that are generally inserted into a heated substance. Circulation heaters are used to heat moving or circulating fluids. Duct heaters are used to heat moving gas streams. Immersion heaters are used in applications that require the heater to be immersed in the substance being heated. For example, over-the-side heaters are immersion heaters that hang over the side of a tank of heated material. Both radiant and infrared heaters use a reflective shield to direct radiant heat onto a heated surface. Common types of infrared heaters include metal-sheathed tubular heaters, quartz tubes and lamps, gas-fired catalytic heaters, flat faced panels and ceramic emitters.

Explosion proof heaters vary in terms of performance specifications and features. Performance specifications include maximum sheath temperature, maximum AC voltage, maximum current, available wattage, and maximum watt density. Watt density, a measure of how quickly heat is transferred, is calculated by dividing the available wattage by the area of the heated surface. In terms of features, some explosion proof heaters are immersible, corrosion resistant, or rated for cryogenic use. Others are equipped with an internal temperature detector, an adjustable thermostat, or weatherproof housing. Devices that are equipped with thermowells facilitate the use of thermocouples or other temperature sensors. Custom heater designs are sometimes available. Explosion proof heaters that bear the UL mark have been approved by Underwriters Laboratories (UL), a product testing organization. 

Explosion proof heaters are constructed with housings that can withstand explosions, sparking and flames during the heating of materials. Most devices include a protective sheath that covers the heating element. There are several basic types of explosion proof heaters. Cartridge heaters are cylindrical devices that are generally inserted into a heated substance. Circulation heaters are used to heat moving or circulating fluids. Duct heaters are used to heat moving gas streams. Immersion heaters are used in applications that require the heater to be immersed in the substance being heated. For example, over-the-side heaters are immersion heaters that hang over the side of a tank of heated material. Both radiant and infrared heaters use a reflective shield to direct radiant heat onto a heated surface. Common types of infrared heaters include metal-sheathed tubular heaters, quartz tubes and lamps, gas-fired catalytic heaters, flat faced panels and ceramic emitters.

Explosion proof heaters vary in terms of performance specifications and features. Performance specifications include maximum sheath temperature, maximum AC voltage, maximum current, available wattage, and maximum watt density. Watt density, a measure of how quickly heat is transferred, is calculated by dividing the available wattage by the area of the heated surface. In terms of features, some explosion proof heaters are immersible, corrosion resistant, or rated for cryogenic use. Others are equipped with an internal temperature detector, an adjustable thermostat, or weatherproof housing. Devices that are equipped with thermowells facilitate the use of thermocouples or other temperature sensors. Custom heater designs are sometimes available. Explosion proof heaters that bear the UL mark have been approved by Underwriters Laboratories (UL), a product testing organization. 

Heather sheath materials for explosion proof heaters include aluminum, brass, copper, iron, nickel alloy, steel, and stainless steel, rubber, and proprietary materials. Aluminum, a metallic element with good electrical and thermal conductivity, is resistant to oxidation. Brass provides good strength and conductivity, excellent corrosion resistance and high temperature ductility, and low magnetic permeability. Steel, a commercial iron that contains carbon, is malleable under suitable conditions. Stainless steel is chemical and corrosion resistant and can have relatively high temperature ratings. Rubber heater sheaths are made of natural compounds such as gum rubber (polyisoprene), styrene butadiene (SBR), or synthetic rubber materials.