Product · O2 Sensors
O2 Sensor for Refrigerated Containers
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Application
The O2 sensor for refrigerated containers measures oxygen from 0 to 25 Vol% and delivers the reading over Modbus RTU on RS485, for controlled atmosphere (CA) reefer units carrying cargo through the cold chain.
Luminescence quenching, not a heated cell
Oxygen is measured optically, by ratio-metric decay-time luminescence quenching, instead of with the heated zirconia cell that has been the established technology in reefer containers. That means lower power consumption, minimal drift and less service.
A span you can take on deck
Ambient air is the reference: a span at 20.8 % O2 with barometric correction, without calibration gas and without taking the sensor out. One year is the recommended interval, and the job belongs with the PTI. Readings are given in Vol%, reflecting the partial pressure of oxygen and normalised to standard pressure by the internal barometer.
One measurement, or three
Alongside it in a CA unit: CO2 sensor for refrigerated containers, humidity sensor for refrigerated containers — or all three in the Hybrid Sensor for refrigerated containers, on one connection.
Properties
| Measurement | Oxygen, 0–25 Vol%; 14-bit resolution |
|---|---|
| Measuring principle | Luminescence quenching by oxygen, ratio-metric decay-time measurement |
| Accuracy | ± (1.5% of range + 3% of reading) above 2% of full scale; factory calibrated in two points at 13 °C and 1013.25 hPa |
| Compensation | Internal barometer and temperature element correct the reading; values are displayed in Vol%, reflecting the partial pressure of oxygen and normalised to standard pressure |
| Stability and response | Long-term stability < ±4.5% FS over two years; time constant τ63% < 5 min. Operational less than 1 minute from power-on, full performance within 20 minutes |
| Calibration | Recommended at 1-year intervals: span calibration in ambient air at 13 °C and 20.8 % O2, with barometric correction and a stabilisation period above 45 minutes; can be executed during reefer PTI |
| Operating conditions | −5 to +30 °C at full accuracy, −20 to +60 °C at reduced accuracy; 0–100 %RH, resistant to condensing environments. Storage −40 to +80 °C |
| Communication | 2-wire RS485, Modbus RTU; 9600, 19200 or 115000 bit/s, software selectable |
| Supply | 12 VDC (8–15 V), protected against overvoltage and reverse polarity; peak < 60 mA, average < 10 mA |
| Electrical connection | Integrated Deutsch DT04 receptacle (DT06 plug); RS485 circuit protected to 60 V, no damage from miswiring |
| Housing and mounting | 52.5 × 52.5 × 36.5 mm; two Ø6 mm holes, 54 mm centre to centre, for rivet or screw |
| Protection | IP67; measuring cuvette behind a 1 µm hydrophobic and oleophobic PTFE membrane |
| Environmental testing | Salt spray ASTM B117, 168 hours, no visible corrosion; vibration IEC 60068-2-64; shock IEC 60068-2-27 |
| EMC | EN 61000-6-3 (emission); EN 61000-6-2 (immunity) |
| Also available as | A CO2 sensor and a humidity sensor for refrigerated containers, and the Hybrid Sensor — same housing, same connector, same Modbus interface |