Electrochemical Oxygen Transmitter

OxyTrend is an Oxygen analyser based on electrochemical sensor. It can be configured as a 2-wire loop powered transmitter or, connecting further 2 or 3 wires, it can also have serial output RS485 ModBus RTU (in alternative or in addition to the analog 4-20 mA).

 OxyTrend can integrate 9 alternative types of sensor, depending on the measure to be achieved (from low traces, up to 100%). All sensors are insensitive to the presence of many background gases and hydrocarbons, making this instrument suitable for a variety of applications.

 Simple, reliable and cost-effective solution to measure O2 in extractive applications in safe and hazardous area (ATEX) Zone 1 / Zone 21

Measureable Gas

Oxygen [O2]

Main Features

High Performances

  • Two-wire, loop powered 4-20 mA transmitter
  • Four or five-wire connection in case of use of the RS485 serial interface or 4-20 mA + RS485 respectively
  • ModBus RTU Master or Slave selectable by menu
  • Connectable with the ADEV 8RO4DI external module by RS485 to have 8 relays output and 4 digital inputs
  • Unique hardware for all wiring connection types
  • Optical through-the-glass buttons allowing menu operation without opening the housing
  • Graphical LCD Display with visualization in Auto-Range and possibility to switch to trend visualization
  • Use friendly menu and intuitive interface
  • High Accuracy Galvanic Sensors
  • Microprocessor-based technology and inner routine of electronic zero autocalibration
  • User selectable range
  • The version for hazardous area application is Ex-Proof and doesn’t require any Zener barrier in non-hazardous location
  • Low Maintenance
  • Sensor lifetime indication
  • NAMUR error indication

9 Different sensors

TYPE CODE Application
Trace (PPM) A59014 0-10 ppm low range, used in most industrial                 applications
Trace (PPM) A59013 0-10 ppm low range, used when acid gases are present (CO2 > 0.1%, etc.)
Trace (PPM) A59002 Optimized for extra low traces, 0-1 ppm low range
Trace (PPM) A59003 Optimized for extra low traces, 0-1 ppm low range when acid gases are present (CO2 > 0.1%, etc.)
Percent A59021 General purpose O2 Measurement. LDL 1000 ppm, used mainly for long life percent applications
Percent A59022 General purpose O2 Measurement. LDL 1000 ppm, used when acid gases are present (CO2 > 0.1%, etc.)
Hybrid A59023 For measuring 20 ppm to 25% with regular                 exposure to ambient air
Purity A59025 Designed for measuring elevated O2 (21.0% – 100%)
Trace (PPM) A59031 0-1 ppm extra low range, optimized for Natural gas       applications (stream with H2S up to 500 ppm)

European Compliance

  • Low Voltage Directive 2014/35/EU
  • EMC Directive 2014/30/EU
  • Directive ATEX 2014/34/EU


ATEX certification for Zone 1 / Zone 21 with protection mode:

II 2 G D     Ex db IIC T6 Gb

Ex tb IIIC T85°C Db



ATEX Certificate Number CESI 20 ATEX [Pending]


Range1 ppm ÷ 100% FS (user settable)
Accuracy± 1% of FS (at constant conditions)
Repeatability± 1% of FS (at constant conditions)
Linearity± 1% of FS (at constant conditions)
Resolution0.005 ppm on 0-10 ppm range
0.01 ppm or percent on other ranges
CompensationIntegrated (temperature)
Sample FlowrateGeneral purpose: 500-1000 cc/min.
ATEX: recommended 500 cc/min.
PressureVent to atmosphere
Atmospheric pressure effect± 0.1% of reading per mbar
Cell life17 ÷ 24 months at 25°C, 1 atm.
Response Time90% of final FS reading: < 10 sec.
Recovery time
(only for cells for ppm)
If a cell is exposed for 60 sec. in Air, 1 hour of N2 purging it is necessary to go back again < 10 ppm O2
DisplayBacklit graphic LCD display with visualization in auto-range
Output:Loop 4-20 mA (two-wires)
RS485 ModBus RTU (four-wires)
Loop 4-20 mA + RS485 (five-wires)
Relays and Digital Inputs8 relays + 4 digital inputs (only combined with ADEV 8RO4DI external module)
Operative Temperature0 ÷ +50°C
Relative Humidity:90% max.
Power Requirements16,5 ÷ 30 VDC; max current: 23 mA
Max. Load Resistance (RL)Depends on applied voltage
Wiring ConnectionsN°2 threaded holed 1/2” NPT-F
Pneumatic ConnectionsStandard: 1/8” NPT-F
Optional: 1/8” or 1/4” or 6 mm compression tube fittings in AISI 316
Available KF40 connection (only safe area)
Weight:about 0,8 kg


Trace O2 in pure gases

Natural Gas & Biogas

Glove box purge and leak detection

Annealing furnaces

Air separators

Nitrogen & Hydrogen generators

Pure gaseous hydrocarbons streams

Chemical & Petrochemical

Steel & Metal processing

Reducing processes

Welding gases

Inerting control

Semiconductor wafer machines

Heat treatments

Sampling System

OxyTrend needs an external sampling system able to deliver an almost clean sample gas to the analyser at the proper temperature, pressure and flow rate.

ADEV has a wide experience in process and can provide the EC9600 transmitter combined with a sample and condition system designed for the specific application requirements. Contact ADEV for details.

Measuring Principle

ADEV sensors are specific for Oxygen. They measure the partial pressure of Oxygen from low ppm to 100% levels in inert gases, gaseous Hydrocarbons, Helium, Hydrogen, mixed gases, acid gas streams and ambient air.

Oxygen, the fuel for this electrochemical transducer, diffusing into the sensor reacts chemically at the sensing electrode to produce an electrical current output proportional to the Oxygen concentration in the gas phase. The sensor’s signal output is linear over all ranges and remains virtually constant over its useful life.