Carbon Potential Oxygen Probes

How a carbon potential oxygen probe works

The zirconia measuring element generates a voltage that depends on the difference in oxygen concentration between the furnace atmosphere and a reference air supply flowing through the probe. The controller reads this voltage, typically 0 to 1200 mV with a response time under 1 second, and combines it with the furnace temperature to calculate the atmosphere's carbon potential, then trims the gas mixture to hold the target %C at the part surface.

Choosing a CarboProbe

• Repairability: the CarboProbe ZI Pro uses an interchangeable ZrO2 ball as its measuring element, so a worn element can be swapped without replacing the whole probe. It needs a higher reference air flow, 20 to 30 l/h.
• Sensor stress: the CarboProbe ZS Pro uses independent calibrated compression springs to limit mechanical stress on the sensor in difficult conditions, at Ø25 mm, with a lower reference air flow of 1 to 6 l/h.
• Drop-in replacement: the CarboProbe ST E is built as a direct replacement for widely used probe designs, with a standard 4-pin plug, so it can often replace an existing probe without rewiring the controller. Tell us your current probe and we'll confirm.
• Connector type: the ZI Pro and ZS Pro use a gold-coated LEMO connector and are interchangeable with each other without rewiring; the ST E uses a standard 4-pin cord plug instead.
• Length: all three are available from 350 to 1200 or 1300 mm depending on model, to suit the furnace wall thickness.
• Thermocouple: each probe is available with a Type K, S or N thermocouple, or without one where the furnace already has its own temperature measurement.

All three probes are 100% factory tested with a test certificate included. They suit carburising, carbonitriding and neutral hardening furnaces, and endothermic gas generators. For furnace surface temperature, see Infrared Pyrometers.