Oxygen probe

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General information
The ZIROX vacuum oxygen probe uses a potentiometric zirconia (ZrO2) solid electrolyte cell as the sensing element. A voltage between measuring and reference electrodes, proportional to the logarithm of the oxygen partial pressure ratio, is generated and can be converted to oxygen partial pressure via the Nernst equation. The connection head integrates heater control, signal processing electronics and an internal membrane pump for reference gas supply.

Applications
The probe is intended for determining oxygen partial pressures in low‑pressure equipment. Typical uses include vacuum processes such as PVD, magnetron sputtering and other plasma or surface treatment processes, as well as material science investigations.

Calibration note
Unlike atmospheric ZIROX probes, the vacuum probe is not calibration‑free due to the internal heater location and pressure‑dependent thermal conditions at the measuring electrode (isothermal electrodes cannot be guaranteed). For process control, empirical calibration often suffices; for accurate measurements the user must perform test calibrations.

Technical data — Vacuum probe

• Insertion length: 140...300 mm
• Probe diameter: 6 mm (16 mm with protection tube)
• Mass: 1.5 kg
• Connection head dimensions: 150 x 63 x 35 mm
• Protection degree: IP54
• Flange: KF40 (other flanges on request)
• Max. temperature at flange: 60 °C
• Power supply: 24 V DC ± 10 %
• Current consumption: 1.2 A
• Heating power: 30 W
• Pressure range: 1.5 x 10^5 ... 1 x 10^-5 Pa
• Sensor voltage range: 0...400 mV or 0...1200 mV (switchable on PCB)
• Oxygen partial pressure range: 1 x 10^5 ... 1 x 10^-21 Pa
• Output signal: 0–20 mA
• Accuracy: < 5 % relative error (process use)
• Sensor operating temperature: 700 °C (electronically controlled)
• Offset (with protection sleeve): -15...-20 mV
• Helium leak rate: < 10^-8 mbar·L/s
• Permissible gas flow: max. 10 m/s
• Reference gas: ambient air
• Reference gas flow (internal pump): approx. 5...10 L/h

Plug assignment
Connector type: Type 423, 6‑pole, Binder (Order No.: 99-5622-15-06)

• 1: +24 V
• 2: GND
• 3: + Iout (20 mA corresponds to 400 or 1200 mV as adjusted)
• 4: - Iout
• 5: Ready contact (potential‑free) — 60 V/1 A DC or 125 V/1 A AC
• 6: (no assignment)