Product Sheet

Zirconia Probes
for the Simultaneous Measurement of Oxygen and Combustible Gases

The In-situ Probe AMS 3211-1500		The ATEX certified Probe AMS 3211-1500-EX

Content

General Description of the Measuring System
ZrO₂-probe for the Measurement of Oxygen and Combustible Gases
Application Areas
System Features
Properties and Limitations
Design of the Probes

The Measuring Probes
In-situ Probe AMS 3211-1500
In-situ Probe AMS 3211-1500-EX

The System Components
Pneumatic Unit and Calibration
Electronic Controller AMS 3220 - Twin-version

The Sensors
The Dual Sensor
Oxygen-sensing Part
The COe-sensing Part

Technical Data
Probes
Electronic Controller AMS 3220 - Twin-version



Product Sheet

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ZrO₂-Probes for the Simultaneous Measurement of Oxygen and Combustible Gases - also for EEx-zone 1
The wide range of applications of ZrO₂-probes for the measurement of Oxygen in flue gases is well known and widely accepted. An additional requirement however is the simultaneous measurement of combustible gases, mainly Carbonmonoxide, but also Hydrogen or unburned Hydrocarbons in order to determine the optimum of combustion or process efficiency.
AMS offers a fast, versatile and cost effective instrument for direct in-line measurement, using a newly developed dual-sensor for measuring simultaneously O₂ and Combustibles (measured as CO-Equivalent COe).
A EEx-approved version for zone 1 is also available (ATEX II 2G EEx d IIB+H2 T3).

Applications
The Oxygen measuring units are used for the determination of the Oxygen concentration in flue gases of incinerators or in pure industrial gases. Simultaneously the concentration of combustible gases, mainly Carbonmonoxide, but also Hydrogen or unburned Hydrocarbons can be measured in order to determine the optimum of combustion or process efficiency, covering these measuring ranges:

• Oxygen standard range: 0,1 ... 25 vol-% O₂
• Carbonmonoxide equivalent: 0 ... 1000 ppm COe

at temperatures up to 350 °C.

The in-situ probe AMS 3211-1500 is exposed directly to the flue gas flow. This set-up allows the sample extraction and conditioning system to be omitted.
Stainless steel 1.4541 is the standard material of the probes. For the use in corrosive gases probes made from INCONEL 600 are available.
The length of the probes is 150 mm until 1000 mm, the ATEX-version from 150 mm up to 860 mm.

A EEx-approved version for zone 1 is also available (ATEX II 2G EEx d IIB+H2 T3).

System Featuress

• Dual sensors for simultaneous measurement of O₂ and CO-equivalent
• Specially AMS designed sensor for flue gas applications exchangeable by the customer
• Gas wetted parts made from stainless steel or even INCONEL 600
• Probe lengths from 150 mm upto 1000 mm
• Gas temperatures up to 350 °C
• A EEx-approved version for zone 1 (ATEX II 2G EEx d IIB+H2 T3).
• Electronic controller:
  Self diagnostics with fault signals
  Automatic calibration
  Plausibility check of the correction data

Properties and Limitations

• The sensors need Oxygen for proper operation; they must not be operated in reducing atmospheres.
  
  
• The sensors are very sensitive to small concentrations of combustible gases; they should not be used at concentrations higher than a few thousand ppm COe.
  
  
• By choosing the appropriate operating temperature, the sensitivity of the sensors can be shifted
  either towards Carbonmonoxide/Hydrogen or towards Oxygen.
  
  
• Every combustible gas component results in a different sensitivity. The sensitivity for Hydrogen is approximately 10-fold against CO; the sensitivity for Methane is only a fraction of that for CO. This has to be taken into account, when using the sensor in gases, which may contain different
  combustible gas components.
  For all combustible gases the cross interference is determined individually during the application.
  
  
• The sensor is best used for detecting the starting point of the formation of COe (i.e. for determining the point of optimum burner efficiency). Because of the various cross interferences to either combustible gases, it is not recommended to use it for a control of a specific CO-concentration level.
  
  
• This is NOT a combustible sensor! The sensitivity to 1 vol% Methane (e.g.) corresponds only to
  a few ppm of Hydrogen! The sensor will respond to any other combustible gas, but the strength of reaction must be determind individually.

Design of the Probes System
The oxygen measuring system consists of the ZrO₂-probe with temperature controlled measuring cells, the electronic controller as well as of the pneumatic unit for the air supply. The measuring procedure for Oxygen is based on the galvanic oxygen concentration cell with solid electrolyte (non-Nernstian ZrO₂-sensor).
To match the varying application areas, different probe models can be supplied, the in-situ-probe AMS 3211-1500 and the ATX-certified probe AMS 3211-1500-EX.
Standard material for the probes is stainless steel 1.4541 as well as INCONEL 600 for corrosive gases (option).
The electronic controller, built into the pneumatic cabinet, is the same for all probes.

The In-situ Probe AMS 3211-1500
The probe design is based upon the well proven probe AMS 3211-500. The dual sensor
is located next to a sintered filter and exposed to the flow of the flue gas. An optional
shield protects the filter against abrasive dust particles.
The reference gas (instrument air) and calibration gases are supplied to the sensor via
tubes integrated into the probe.
The standard length of the probe is 500 mm; the maximum flue gas temperature is 400°C.
Standard Material for the probe is SS 1.4541; for applications in corrosive gases, the probe
is optionally available in INCONEL 600.

The In-situ Probe AMS 3211-1500-EX
The probe design is based upon the well proven in-situ O₂-probe AMS 3211-860/150 with temperature-monitor- and de-powering unit AMS-TWD2.
The probe carries it’s own ATEX certificate as 2nd supplement to

BVS 05 ATEX E 002 X

and the protection is certified as

II 2G  EEx II B+H2 T3

The dual sensor is located next to a sintered filter, which itself is certified as suitable flame barrier and exposed to the flow of the flue gas. An optional shield protects the filter against abrasive dust particles.
The reference gas (instrument air) and calibration gases are supplied to the sensor via tubes integrated into the probe.
The standard length of the probe is 500 mm; the maximum flue gas temperature is 400°C.
Standard material for the probe is SS 1.4541; for applications in corrosive gases, the probe is optionally available in INCONEL 600.

Pneumatic Unit and Automatic Calibration
To operate the probes AMS 3211-1500 or AMS 3211-1500-EX, a reference gas (instrument air quality) will be needed.
In intervals of 3 to 6 months, a calibration with air and a calibration gas is recommended.

This unit comprises a pressure controller for the air supply, filters,
a manual valve and flow meters for the reference air and the calibration
gas.

Electronic Controller AMS 3220 - Twin-version
A twin version of the electronic controller AMS 3220 features two signal inputs for the sensors and issimultaneously the central supply-, control and evaluation unit for the Oxygen sensor as well as for the sensor for
the COe-equivalent measurement. The unit can be delivered in different housing models.
The operation and the features of the twin version are identical to the standard version described as follows.
Programming and controlling the entire measuring system is executed
with only three push buttons: one for the operation mode, two for the cursor.
A display featuring two LCD rows indicates the measuring value and
user fed data as well as the operation directions in plain text messages.
The programming level, accessible via a specific service mode, is protected against unauthorized operation by means of a hidden key.
The self-diagnostics of the controller with the corresponding fault signals reduce the usually time-consuming monitoring reasonably.

All instrument parameters, e.g. the calibration and alarm data, the assignment of the display lines, and of the two analogue outputs, can be comfortably set at the control unit. The calibration limits will be laid down in the E-PROM of the controller correspondingly.

Particularly important regarding the reliability of the O2 and COe-equivalent measurement is of course the identification of errors and hence the error message while calibrating: The stability of the measuring signal during calibration and the plausibility of the calculated correction data are subject to the continuous checking by the electronic controller.