If the solution has corrosive properties, that must also be taken into consideration. 2-inch or NPT is normally designated. Kim Hotstart's screw plugs are made of aluminum but, depending on customer needs and applications, steel, stainless steel or brass is also available. In addition to standard threaded immersion heaters, threadless units are now available. Kim Hotstart's threadless heaters allow for installation by welding the threadless tank adapter to the tank.
Heaters are available for hydraulic fluid, diesel fuel and oil supply and storage tanks.
The simplest solution is to install multiple elements with shorter probe lengths to provide the required kW. For example, if 6 kW is required, you could install three 2 kW elements. If only one opening is available, determine the maximum length of the immersion heater probe that can be used. Additional openings allow more flexibility with installation options. Equipment housed in a heated building will require less wattage for heating than equipment installed outside where it is affected by wider temperature variances plus the wind-chill factor. Low watt density is preferable to prevent burning oil.