9 Things to consider when specifying electric heating element
When specifying a heating element, the details of the application are key. The more application information we have, the easier it will be to find an element to suit. You should also consider the following points.
1. Power requirement – When specifying a heating element, it is crucial that the size of element chosen is capable of delivering enough power to achieve the process temperature, it’s always a good rule of thumb to try and incorporate a slightly larger physical heater than required thus giving them some room for manoeuvre should you need to increase power.
2. Loadings – Supply voltage and power (wattage) are two factors to consider when specifying an element. Generally speaking, elements can be manufactured to an unlimited number of different loadings, they do however have maximum and minimum watt density’s that the can be manufactured to.
3. Required ramp up time – How fast do you want the process to be heated? Remember, it’s not always the fastest that wins the race, by this we mean a slower rise to temperature puts less dynamic strain on the heater and should therefore extend life expectancy of the unit.
4. Product being heated – Gas, solid or liquid products all absorb heated energy at different rates. The correct style of heating element and its power output should be able to maximise the efficiency of your process.
5. Element sheath material – Predominantly heating elements are manufactured from just a few different materials; variations of Stainless steel being the most common sheath materials used, alongside, Brass, Aluminium, Zintec plated steel and ceramics.
6. Mounting method – Heaters can be fixed within an application in countless number of ways, although a good general rule is to stick with what`s already available from the standard designs before diversifying.
7. Overall dimensions and shape – The final shape of your intended style of heater could be very simple such as a cartridge or strip heater, or become far more complex item such as a Cast in Heater with added cooling, or even a process circulation heater that has explosion proof terminal housing and control system.
8. Termination method – Heaters can be terminated to the power supply in a vast number of different ways. Again, it’s best starting with the standard listed terminals before diversifying. Standard termination, such as flexible leads and threaded terminal pins are generally the most common on electric heater.
9. Control – Heaters can be run with or without control, however when running un-controlled you should be always sure that the application can’t run away with itself and cause damage. Same thing for the heating of liquids, if the liquid level drops below a certain amount then the heaters should be switched off or not be able to do any damage to the application or themselves if run dry.