ENOTEC COMTEC 6000 ATEX GasEx Analyzer Maintenance, Calibration, and Troubleshooting Guide

ENOTEC COMTEC 6000 ATEX GasEx Analyzer Maintenance, Calibration, and Troubleshooting Guide

System Overview and Measurement Principles

COMTEC 6000 ATEX GasEx is an in-situ flue gas oxygen (O ₂) and CO equivalent (COe) analysis system designed specifically for explosive environments. The system consists of measuring probes installed in the flue and electronic units for voltage supply, gas supply, and signal processing. The probe uses zirconia sensors to measure O ₂ concentration and MXP sensors to detect COe values, which are widely used in combustion efficiency monitoring and emission control.

The O ₂ sensor is located at the tip of the probe and is adjusted to a constant temperature of 800 ° C. Based on the Nernst equation, the oxygen partial pressure difference between the reference air (20.95% O ₂) and the measured gas is converted into a mV signal to calculate the oxygen concentration in the flue gas. The COe sensor uses catalytic electrodes to oxidize incompletely burned combustible gas molecules (such as CO, H ₂, C ₓ H ᵧ), generating a voltage signal related to the concentration of COe. These two sensors work together to provide critical data for combustion optimization.

Safety reminder: The electronic unit and probe of this analyzer are both ATEX certified and suitable for Zone 1-2 areas. The probe design temperature level is T3, with an ambient temperature range of -20 ° C to+70 ° C. The flue gas temperature should not exceed 500 ° C (if a cooling protection tube is used, it can withstand higher temperatures). During operation and maintenance, safety regulations must be strictly followed to avoid opening the casing when it is live.

Installation points and initial operation

2.1 Installation requirements for electronic units

The electronic unit should be installed in a location that avoids vibration, is away from heat sources, and is easy to operate. Maintain a minimum distance from adjacent objects (200mm at the top and bottom, 50mm on the side) to ensure an IP66 protection level. The ambient temperature should be controlled between -20 ° C and+55 ° C. During installation, an external power switch should be used and the line voltage should be consistent with the nameplate.

2.2 Probe installation and gas path connection

The probe should be installed horizontally to achieve the fastest response time, and the flange installation angle should be 1 ° to 3 ° to facilitate the reflux of condensed water. The shielding layer of the probe cable is only grounded at the electronic unit end, and grounding at the probe end is strictly prohibited. The gas path connection needs to distinguish between reference air (blue) and test gas (green) to ensure airtightness. For probes with a length exceeding 2000mm, supports should be installed every 2 meters in the flue to prevent bending.

2.3 System Power On and Initial Settings

After the first power on, the system will prompt to select language, set date and time, enter TAG number, and probe cable length. Special attention: The length of the probe cable must be accurately inputted, as incorrect settings may result in measurement deviation or even damage to the MXP sensor. Subsequently, the system enters the probe heating stage, where the O ₂ sensor heats up first and the COe sensor heats up later. Automatically enter measurement mode after heating is completed.

Daily maintenance and calibration operations

3.1 Calibration menu and process

COMTEC 6000 supports 1-point calibration and 2-point calibration, which can be performed separately for O ₂, COe, or both simultaneously. Calibration can be manually initiated through CAL-MENU, or timed or remotely triggered through the ACAL (Automatic Calibration) function.

1-point calibration: Use only test air (20.95% O ₂) to determine sensor offset. Suitable for daily calibration of O ₂ sensors.

2-point calibration: Use test air and test gas (such as 2.1% O ₂ or 1000ppm CO) to determine offset and slope. It is recommended to perform after replacing the sensor or undergoing major repairs.

During the calibration process, the system will prompt the application of test gas and automatically record the sensor response. If the sensor signal is unstable, the system will report an error of "sensor calibration failure". At this time, the "test gas application time" can be appropriately extended (default 10 minutes, adjustable to 30 minutes).

3.2 Automatic Calibration (ACAL) Settings

ACAL can be automatically executed at time intervals or triggered through digital input. When enabling ACAL, ensure that the test gas cylinder is normally open and check the flow setting (test air 150-180 l/h, reference air 30-40 l/h). ACAL can be configured for 1-point (air only) or 2-point calibration.

3.3 Flow adjustment and gas path maintenance

For models with integrated pneumatic units, the reference air and test air flow rates can be adjusted through regulating valves. The reference air flow rate should be maintained at 30-40 l/h, and the test air flow rate should be 150-180 l/h. If an external pneumatic unit is used, it can be monitored through a pressure regulator (factory set to 1 bar) and a flow meter.

Attention: If the reference air flow rate exceeds 60 l/h, it may cause a decrease in the temperature of the O ₂ sensor, triggering the "O ₂ probe temperature too low" error.

Sensor replacement and troubleshooting

4.1 Replacing the O ₂ sensor

Turn off the system power and remove the probe core.

Unscrew the filter head and remove the test gas distributor.

Loosen the 4 hexagon socket screws on the measuring unit flange and remove the old sensor.

Clean the flange surface and install a new sensor (pay attention to using new gaskets and screws).

Reinsert the inner core to ensure even spring pressure.

After installing the probe, perform 2-point calibration after running for 24 hours under process conditions.

4.2 Replace COe sensor

Warning: Before replacement, the COe measurement must be set to OFF through software, otherwise the new sensor may be immediately damaged.

Disconnect the COe sensor wiring (terminals 11-14).

Loosen the locking nut and remove the clamping ring, O-ring, and retaining ring in sequence.

Remove the old sensor (note possible high temperature).

Prepare a new sensor: Insert the clamping ring, O-ring, retaining ring, and locking nut, paying attention to the inclined surface facing the O-ring.

Insert the new sensor and tighten the locking nut. The system needs to be tightened again after running for 2 hours.

Reconnect the wiring, power on, enable COe measurement through software, and input the parameters on the sensor test certificate (RH ₀, Offset, Alpha, Beta, Gamma, Delta, SO ₂ correction values).

Be sure to confirm that the RH ₀ value is correct, as incorrect values can immediately damage the sensor.

4.3 Common faults and solutions

Possible causes and solutions for the fault phenomenon

The measurement value of O ₂ fluctuates greatly, and the wiring is loose, the internal contact of the probe is poor, and the filter element is damaged. Check the wiring and replace the filter head

If the O ₂ display exceeds the range or is too high, the probe or sensor flange may leak, or the flange may not be airtight welded. Check the seal and replace the O ₂ sensor or gasket

O ₂ shows 0% but the expected process is high. Heater failure, thermocouple failure, fuse blown, cable short circuit. Check the heater resistance (about 37.5-47.5 Ω), thermocouple resistance (2-80 Ω), and replace the fuse

No measurement value for COe, arrow displayed beyond physical range, COe sensor malfunction. Perform O ₂+COe sensor inspection and check electrical connections

Refer to low/high air flow rate, incorrect flow setting, insufficient air source, pump failure, and readjust the flow rate. Check the air source and pump

Electronic unit temperature alarm: If the ambient temperature exceeds the range of -20 ° C to+55 ° C, improve ventilation or ambient temperature

4.4 Error codes and relay outputs

The system error relay (terminal 19A/B) operates in the event of hardware failure, thermocouple disconnection, heating failure, calibration failure, etc., and the O ₂ signal output drops to 2.00mA (unless otherwise set). COe related errors output 20.80mA. Users can view specific error information through the system menu and attempt to reset. If the error persists, please contact ENOTEC service.

Long term discontinuation and storage recommendations

ENOTEC emphasizes that heating sensors must operate continuously. Frequent switching of heating power can cause thermal stress and shorten the lifespan of heaters, thermocouples, and sensors. If it must be stopped, ensure that the probe temperature drops below 200 ° C before opening the casing and wait for at least 1 hour. The storage environment shall be dry and ventilated to avoid paint smoke and silicon spray.