Introduction to Immersion Heaters
What is a Immersion Heater?
An immersion heater is a device which is installed in a tank or container to heat a liquid. The installation can be over-the-side, flanged or threaded.
Over-the-side immersion heaters are designed for vessels where through the side immersion heaters cannot be conveniently installed. These heaters are installed through the top of the vessel with the heated portion of the unit along the side or at the bottom of the tank. Natural circulation of the fluid inside the vessel allows for even distribution. Terminal houses or lead wires are provided for power connection.
These heaters are available with heating elements made of copper, steel, stainless steel, cast iron, Incoloy, titanium, and PFA coated. A wide selection of kilowatt ratings, shapes and mounting methods are available to suit many different types of applications.
The large variation in heating element material and shapes of over-the-side immersion heaters offers a wide selection in the application of these units. Water, oils, solvent, plating baths, salts and acids are some of the many liquids and viscous materials commonly heated with immersion heaters. Over-the-side types permit portability, easy removal for cleaning of tanks and heaters, and ample working area within the tank when installed.
Flanged immersion heaters consist of hairpin bent tubular elements welded or brazed into a flange and provided with wiring boxes for electrical connections. Flange heaters are installed by bolting to a matching flange welded to the tank wall or nozzle. A wide selection of flange sizes, kilowatt ratings, voltages, terminal housings and sheath materials makes these heaters ideal for all types of heating applications.
Flanged immersion heaters are one of the most widely used methods for heating liquids (such as water, oil, heat transfer fluid and corrosive solutions). Designed for use in tanks and pressurized vessels, they are easy to install and maintain to provide heat for many processes. The direct immersion method is energy efficient and easily monitored and controlled.
These through-the-side immersion heaters utilize standard pipe flanges ranging from 3" to 14" in diameter to support high tank pressures of liquids. They are installed through a matching companion flange, obtainable from local industrial supply houses, to the tank wall. A wide selection of watt densities, heating outputs and flange sizes and ratings make this an excellent heater for all tanks, vats or irregularly shaped vessels.
Threaded or Screw Plug
Screw plug immersion heaters consist of hairpin bent tubular elements brazed or welded into a screw plug and provided with wiring boxes for electrical connections. Screw plug immersion heaters are screwed directly through a threaded opening in a tank wall or through matching pipe coupling, half coupling or welding flange. Sizes of screw plug heaters are available with ½", ¾", 1", 1¼", 2" and 2½" pipe threads. A wide selection of screw plug sizes, kilowatt ratings, voltages, sheath materials, terminal housings, and thermostats makes these compact heaters ideal for all types of applications.
Screw plug immersion heaters are used for heating liquids in a variety of processes. Those heaters are ideal for process water heating and freeze protection. All types of oils and heat transfer solutions can also be heated using these compact easily controlled units. The direct immersion method is energy efficient and well suited for many applications.
Thermostats or Temperature Control
Many screw plug and flanged type heaters are available with built-in thermostatic controls. In some installations, where there is more than one heater in a tank, you may consider one heater with a built-in control that will control the other heaters by wiring thermostat into the holding coil circuit of a magnetic contactor. If the thermostat is separate from the heater, the thermostat sensing element should be located approximately 4 to 6 inches above the heater. Other types of controls are available where a high degree of accuracy or a more versatile control scheme is required. Electronic controls and complete control panels are easily installed.