JGY Oil Immersion Heating Element

For mineral and heat-transfer oil, keep the sheath below about 3 W/cm². Above that the oil film in contact with the tube begins to crack into carbon, and because carbon insulates, each successive layer runs hotter than the last. That runaway is the single most common cause of premature failure in oil service. Vegetable and food-grade oils are less tolerant still and want closer to 2 W/cm².

It burns out, usually within minutes. Air removes heat roughly two orders of magnitude more slowly than oil, so an exposed heated zone climbs past the sheath limit almost immediately. Every oil installation should have a low-level cut-out wired to break the heater contactor — that interlock costs far less than the element and the tank clean-up.

JGY2 is the general-purpose element for open or closed oil grooves up to a 300 °C medium temperature. JGY3 is the deep-immersion form for tall tanks, and its catalog B dimension is a minimum liquid level rather than a heated length. JGY4 is for flowing, circulating oil up to 100 °C, where the flow lets a shorter element carry 5 to 8 kW.

Yes, and it is common — but tell us the fluid by name when you inquire. Synthetic heat-transfer fluids differ widely in film temperature limit, and the safe watt density follows the fluid, not the tube. We size the heated length to the fluid's published maximum film temperature.