Cartridge Heater Length-how To Specify Them

When it comes to describing cartridge heaters, some details can be more complex than others. This article aims to resolve any difficulties you may encounter when describing the length of heaters with elbows, right-angle leads, bushings, or other terminations. 

 Here’s the bottom line: If you can see the sheath, measure it, and nothing more! 

 Specifying the length of a cartridge heater with leads protruding straight out of the end hardly requires discussion. The heater length is simply the heater length – it couldn’t be simpler. But what if you add a bushing? Do you include the threaded bushing length in the measurement? How about the hex head? 

The answer to both questions is no. Even for a center hex bushing, the principle remains the same. Measure only the visible sheath length up to where it enters the threads – this is what you specify as the insert length. There’s no need to specify anything else regarding the heater length. The same principle applies to heaters with a right-angle copper elbow. Don’t concern yourself with the length of the copper elbow; focus solely on the visible sheath length. Once again, you’re specifying the insert length of the heater. 

For heaters with a right-angle lead wire exit, where the leads emerge through a hole in the side of the heater sheath, things become slightly more complicated, but not overly so. In this case, specify the overall length of the heater from one end of the sheath to the other. The position of the hole for the lead wire exit determines the insert length of the heater, which you don’t need to specify. However, if you choose to specify the insert length, ensure it’s consistent with the typical value. For instance, a 5/8” diameter heater that’s 6” long (overall) would typically have a 5 3/8” insert length. cartridge heater length

There’s one exception to the rule: heaters with stop rings or flanges. In such cases, it’s advisable to specify both the insert length to the underside of the flange and the overall length, especially if there are clearance issues in your application. In any case, if you’re unsure about specifications or if you have any questions, don’t hesitate to contact us. We’re here to ensure you get the right heater for your needs. 

 Please refer to the image below for visual clarification on the concepts discussed here.