Product · CO2 Sensors, Humidity Sensors, O2 Sensors
Hybrid Sensor for Refrigerated Containers – CO2, O2 & Humidity
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Application
The Hybrid Sensor for refrigerated containers measures CO2, O2 and relative humidity in one sensor — one housing, one mounting point, one Deutsch plug and one Modbus RTU connection over RS485.
One cable, one connector, one address
Two Ø6 mm holes at 54 mm centres, one Deutsch DT04 receptacle and one node on the RS485 line, whatever combination of the three values the unit is specified for. All three arrive as Modbus RTU at 9600, 19200 or 115000 bit/s — from the same point in the reefer’s cargo space, measured under the same conditions.
Three measurements, three dedicated principles
CO2 is measured by dual-wavelength NDIR, at 4.26 µm with a reference wavelength at 3.91 µm that holds the reading steady as the optics age. Oxygen is measured optically, by luminescence quenching instead of a heated zirconia cell, which is what gives lower power consumption and minimal drift. Relative humidity is measured by a capacitive element behind a PTFE membrane, with a response time under 8 seconds.
True Vol%, and calibration on deck
The sensor carries its own barometer and temperature element, so both gases arrive corrected to true Vol% at standard pressure. Both gases leave the factory calibrated in two points; afterwards they are re-zeroed and re-spanned against ambient air, with no calibration gas and without taking the sensor out of the unit. Once a year is what we recommend, timed with the container’s own PTI. The humidity element needs no recalibration.
Built for the container
IP67 housing with the measuring cuvettes behind a 1 µm hydrophobic and oleophobic PTFE membrane, salt spray tested to ASTM B117 for 168 hours with no visible corrosion, and vibration and shock tested to IEC 60068-2-64 and IEC 60068-2-27 — for cargo carried through the cold chain in controlled atmosphere (CA) reefer units.
Or one measurement at a time
The same housing is available with a single value where that is all the unit needs — CO2 sensor for refrigerated containers, O2 sensor for refrigerated containers and humidity sensor for refrigerated containers, on the same connector and the same Modbus interface.
Properties
| Measurements | CO2 0–20 Vol%, O2 0–25 Vol% and relative humidity 0–100 %RH (condensing), in one housing |
|---|---|
| Measuring principles | CO2: NDIR, dual wavelength, 4.26 µm sensing and 3.91 µm reference. O2: luminescence quenching, ratio-metric decay-time measurement. Humidity: capacitive element with PTFE filter, high-accuracy version available as an option |
| Resolution | CO2 and O2 14-bit; humidity 16-bit |
| Gas 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; temperature dependence typically < ±0.2% of reading per °C, corrected internally |
| Humidity accuracy | Standard: ±3 %RH at 10–90 %RH, 0–60 °C. High-accuracy option: ±2 %RH at 0–100 %RH, 0–60 °C. Long-term drift < ±1.5 %RH per year, no recalibration required |
| Compensation | Internal barometer and temperature element correct both gas readings; values are displayed in Vol%, normalised to standard pressure |
| Stability and response | Gas measurements < ±4.5% FS over two years; gas τ63% < 5 min, humidity τ63% < 8 s. Operational less than 1 minute from power-on, full gas performance within 20 minutes |
| Calibration | Gas measurements recommended at 1-year intervals, in ambient air with barometric correction and a stabilisation period above 45 minutes; can be executed during reefer PTI |
| Operating conditions | Gas measurements −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 — all three values on one connection |
| 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 cuvettes 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, an O2 sensor or a humidity sensor for refrigerated containers — same housing, same connector, same Modbus interface |