Application example

Heated tank control, end to end

A worked example of the full loop on an immersion-heated tank: low-watt-density elements in the liquid, an RTD in the well, a PID holding setpoint, power switching doing the work and one panel that ties it together.

The challenge

Uniform heat from top of the tank to bottom

A tank looks easy until it is on hold: liquid stratified two feet deep, scale baking onto the sheath, a level that drops below the heater. Holding one temperature throughout takes matched parts, not just a big element.

Immersion Heaters

Flanged, threaded or screw-plug elements sized to the tank volume and liquid, with watt density held low enough that water, oil or plating solution cannot bake onto the sheath.

RTD Sensing

A 3-wire platinum RTD in a thermowell, placed in the working zone of the tank instead of against the wall, so the controller reads what the process actually sees.

PID Control

One PID loop with soft-start ramping, an independent high-limit and a low-level interlock that removes power before the element sees vapor.

How the thermal loop works

Power Switching & Panel

Contactors, SSRs or SCR power controllers sized to inrush and duty, wired into a NEMA enclosure with fusing, indication and a disconnect.

Custom panel builds
The signal chain

How a tank holds temperature

Follow the loop from element to finished process — the same chain we size, wire and document on the bench.

  1. 1

    Immersion Heater

  2. 2

    RTD

  3. 3

    Controller

  4. 4

    Power Switching

  5. 5

    Panel

  6. 6

    Complete Thermal Process

Kettles, vats and CIP duty

What we supply

Sized to the liquid, not to the catalog page

Give us tank dimensions, contents, insulation and start temperature and we calculate heat-up, hold load and watt density — then build the panel around them.

  • Immersion elements in steel, stainless or titanium sheath
  • 3-wire RTDs with matched thermowells and heads
  • PID controller plus independent high-limit protection
  • Contactor, SSR or SCR power switching sized to inrush
  • Low-level and over-temperature interlocks wired hard
  • Schematics, I/O list and O&M documentation with the panel
Corrosive-service and plating tanks
FAQ

Heated tank control FAQ

Still water around 3–5 W/in², agitated water up to about 12 W/in², light oils roughly half of that and heavy or viscous media lower still. Running above the right density bakes film onto the sheath, the element stops rejecting heat, and it fails from the inside out.

Not always. A contactor with time-proportional output is the economical answer for a slow, well-mixed tank. Choose an SCR when the tank must hold tight during draw-off or cold makeup, or when cycling a large resistive load is hammering contactors and flickering the plant voltage.

With a hardwired interlock, not just a control-loop alarm. A level switch removes power at the contactor independently of the PID, and a separate high-limit on its own sensor trips and latches off if the liquid ever stops absorbing heat.

Tell us what's in the tank.

Volume, liquid, insulation and setpoint are all we need to size the loop and quote the panel.

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