For immersion applications of heaters.

Make sure the sheath material and watt density ratings are compatible with the liquid being heated. Immersion heaters used in tanks should be mounted horizontally near the tank bottom to maximize convective circulation. Vertical mounting is possible where limitations prohibit horizontal orientation. Both methods must be located high enough to be above any sludge buildup in the bottom of the tank. Vertical mounting is not recommended. The entire heated length of the heater should be immersed at all times. This makes vertical mounting difficult to properly effect. Do not locate the heater in a restricted space where free boiling or a steam trap could occur. Scale build-up on the sheath and sludge on the bottom of the tank must be minimized. If not controlled they will inhibit heat transfer to the liquid and possibly cause overheating and failure. Extreme caution should be taken not to get silicone lubricant on the heated section of the heater. The silicone will prevent the "wetting" of the sheath by the liquid, act as an insulator, and possibly cause the heater to fail.

Prevent excessive temperatures in process applications.

A reliable temperature control system is imperative to the performance and life of your heaters. The temperature sensing device should be located in a built-in thermowell for maximum accuracy and responsiveness. The protection of a high-temperature limit control can be very important, especially when process temperatures are critical.

Guard against heater contamination.

Contamination is the most frequent cause of heater failure. Any organic or conductive material that can be drawn into the heater by expansion and contraction during cycling can cause an arcing failure in the heater windings. If allowed to collect at the lead end of the heater, contaminants can cause an electrical short between the power pins. Do not allow lubricants, oils, low-temperature tapes or processing materials to remain in contact with the lead end of the heater. Specify a moisture seal if necessary.

Protect leads from damage by high temperatures.

Standard fiberglass-insulated lead wire may be used to approximately 500ºF (260ºC) ambient. If the lead will be exposed to higher temperatures, high-temperature lead wire or ceramic bead insulation should be used. An unheated section of the heater, protruding from the heated part, could enable the leads to run cooler.

Protect leads from damage by excessive movement.

When heaters are mounted in moving machinery, anchor the leads to prevent them from being damaged. Specify a lead protection option.

Heater selection and sizing are important.

Match the heater wattage as closely as possible to the actual load requirements to limit ON/OFF cycling. For fitted-part applications, specify the heater size exactly so it can be tightly fitted. Even small air gaps cause hot spotting.

Ground the equipment.

It's common sense and a safe practice to electrically ground all equipment on which the heater is used. Grounding protects plant and personnel in case of any electrical failure in the heating system.

Regulate voltage.

A 5% variation in voltage results in a 10% variation in heater output.

Prevent excessive cycling.

Excessive cycling can be very detrimental to the life of a heater. The worst cycle rate is one which allows full expansion and full contraction of the heater at a high frequency (approximately 30 to 60 seconds ON and OFF). With simple ON/Off controls, much less frequent cycling can be achieved by closely matching the total wattage to the actual requirements.