Huberg METREX2 Gas Detector User Manual

1.0 Description

The METREX2 is a compact and portable digital gas detection device. Its large LCD screen offers instant readings of gas concentrations, simplifying operation. It supports various probe types for accessing hard-to-reach areas. The device is controlled by a microprocessor that manages sensor functions, keyboard commands, alarm management, data logging, and serial communication for PC data transfer. The METREX2 is ATEX compliant and operates on rechargeable nickel-hydride batteries, providing at least 8 hours of operation on a full charge under normal conditions.

Important: Battery recharging and I/O connections must be performed in safe (non-ATEX) environments.

The METREX2 features three measurement ranges: PPM (parts per million), %Vol (volumetric), and LEL (Lower Explosive Limit). It is equipped with three sensors: a semiconductor sensor, a pair of pellistor sensors, and a pair of volumetric thermal conductivity sensors.

2.0 Keypad and Connections

The device features a keypad with several buttons for operation:

• 1. OFF Button: Power switch.
• 2. Data Logging Button: Records measurements.
• 3. Audible Alarm Button: Toggles the audible alarm on/off.
• 4. PPM/VOL/LEL Switch Button: Changes measurement range.
• 5. Auto-Zero Button: Resets the device to zero.
• 6. 220V Connection LED: Indicates 220V connection.
• 7. Battery Recharge LED: Indicates battery charging status.
• 8. Audible Alarm ON/OFF LED: Indicates the status of the audible alarm.
• 9. Alarm Threshold LED: Indicates an active alarm threshold.
• 10. %VOL LED Scale: Indicates when the %VOL scale is selected.
• 11. Screen: Displays measurement data and device status.

Connections on the device include:

• Air Outlet
• Quick Probe Connector
• Buzzer
• Battery Charger / Serial Port for Data Download
• Protective Cap

3.0 Device Performance

3.1 Power On

To turn on the device, press and hold one of the bottom right keypad buttons (1, 2, 3, 4, or 5) for at least three seconds. Upon power-on, the instrument's serial number is displayed, followed by an audible signal.

The screen will then display the software version (e.g., "Px.x") and "CAL" (calibration in progress). The pre-heating and auto-calibration phase lasts approximately one minute. After completion, the device automatically switches to the PPM scale.

ATTENTION: The device must be switched on in a gas-free environment.

3.2 PPM and %VOL Measurement Ranges

The METREX2 has two measurement scales: PPM and %VOL. After power-on, it defaults to the PPM range, which displays concentrations from 0 to 9900 PPM. The volumetric scale measures from 0 to 100%.

You can switch between these ranges by pressing the PPM/VOL button (4). If a concentration of 1% vol. is detected in the PPM range, the instrument automatically switches to the volumetric range. To switch back from the volumetric to the PPM range, you must press the PPM/VOL button; this is not automatic. The switch to PPM is only possible if the gas concentration is below 10,000 ppm (1%). When the volumetric range is selected, the corresponding LED (10) illuminates.

3.3 LEL Measurement Range

The METREX2 features an LEL (Lower Explosive Limit) scale, activated by pressing the PPM/VOL button (4) for more than 2 seconds. If the audible alarm is active, an audible signal will sound. The LEL scale can only be accessed manually. To return to the PPM or VOL range, briefly press the same button.

For CH4, the LEL measurement range (0-100%) corresponds to 0 to 5% vol. (100% LEL = 5% VOL) on the volumetric scale.

3.4 Alarm

Upon powering on the METREX2, the audible alarm is active and the LED (fig. 11) illuminates. The user can deactivate and reactivate the audible alarm by pressing the alarm ON/OFF button (3) as needed.

If the audible alarm is deactivated but the measured concentration exceeds the preset alarm limit, the visual alarm LED (9) will flash.

Alarm thresholds are adjustable in ppm and volume. Press and hold button (3) for over 2 seconds to display the set alarm limit. You can modify this by holding button (3) and pressing button (4) to increase the value, or button (5) to decrease it.

Since the audible alarm is also controlled by button (3), it is recommended to verify the desired display mode after adjusting the alarm limit.

3.5 Data Logging (Optional)

During readings, up to 500 measurements can be recorded in the METREX2's internal memory. Pressing the data logging button (2) while the device is operating normally freezes the displayed value. The displayed value flashes, and an audible signal sounds to indicate this state. The pump also stops.

The device remains in this mode until another button is pressed, which restores normal operation. Pressing button (2) again displays the number of the last recorded measurement (e.g., "n 0" means no data recorded). Pressing button (2) a third time records the new measurement consecutively in the internal memory and returns the device to normal operation.

To view recorded measurements before transferring them to a computer, press the data logging button (2) twice to display the last recorded measurement number. Use buttons (4) or (5) to scroll forward or backward through the measurements. To save the desired measurement, hold the button pressed for at least 2 seconds. To return to normal mode without saving data, press button (3).

To cancel all recordings, connect the METREX2 to the battery charger and power supply. Press buttons (2) and (5) simultaneously for at least 2 seconds. The device will emit a signal and display "CANCEL" on the screen to confirm cancellation.

3.6 Auto-Zero

Pressing the zero button (5) sets the device to zero. This function is only executable at gas concentrations below 1800 ppm.

3.7 Screen Backlight

To activate or deactivate the screen backlight, press buttons (3) and (5) simultaneously.

3.8 Battery Recharge

IMPORTANT: Use only the supplied Huberg charger for recharging batteries. Ensure the instrument is switched off before charging. Connect the charger to a 220V outlet and plug it into the METREX2's charging port (4). The instrument will automatically enter recharge mode. The charging voltage is displayed on the screen during charging.

This procedure must be performed in a safe environment.

Two LEDs will be illuminated: one for mains connection (fig. 20) and one for battery charging (fig. 21). The second LED flashes rapidly during charging and slowly when the battery is fully charged. Recharge time is approximately 10 to 12 hours.

3.9 Battery Status Visualization

The battery status is always displayed in the lower left corner of the screen. The instrument monitors battery voltage. When the battery is nearly depleted, the "Empty" icon appears. The "Low battery" status indicates that the device will function for another 10 minutes before shutting down, displaying "STOP". The device must be recharged using the supplied charger. Charging must be done in a safe (non-ATEX) zone.

During charging, the screen displays "LOAD" (Fig. 23). Full recharge time is 10 to 12 hours.

4.0 Gas Type Selection (Optional)

In addition to CH4 calibration, the METREX2 can be optionally supplied with GPL and/or town gas calibrations. The user can change the gas type during normal operation after auto-calibration. To do so, press and hold buttons (4) and (5) simultaneously. The screen will briefly display the new gas type. The METREX2 is then ready to measure with the new gas.

When the METREX2 is powered on, the screen displays the current gas setting: CH4, C3H8, or None (CIT).

WARNING: Gas type selection must be performed in a gas-free zone.

5.0 Pump Lock

The METREX2 can be equipped with an optional pump lock function. If the flow is continuously obstructed for approximately 4 seconds, the METREX2 stops measuring, and the screen displays "Poff" (fig. 28). To resume measurement, press any of the four buttons below the screen (2, 3, 4, or 5).

6.0 Periodic Maintenance and Calibration

For correct and precise operation and reliable measurements from the METREX2, QED Environmental Systems recommends sending the device to QED Environmental Systems or an authorized service distributor for maintenance and calibration annually.

After inspection and adjustment, a calibration certificate will be issued in accordance with ISO standards. To verify proper functioning, QED Environmental Systems recommends regular checks using the HANDYGAS instrument, according to its operating instructions. For more information, refer to section "8.0 Accessories" and the HANDYGAS technical data sheet.

7.0 Warranty

The METREX2 is covered by a warranty against manufacturing defects, in accordance with legal provisions. During this period, QED Environmental Systems will repair malfunctions caused by manufacturing defects. The warranty does not cover damage caused by improper use or handling of the device. It will be voided if unauthorized personnel perform repairs. This warranty is valid in all countries where QED Environmental Systems or an authorized agent distributes the METREX2. QED Environmental Systems offers no warranty on calibration.

IMPORTANT: Please read the instructions carefully before using the device to ensure its proper functioning. No warranty will be valid if the device is not used in accordance with the instructions in this manual. QED Environmental Systems is available to provide any further information regarding the use and maintenance of the device.

WARNING: QED Environmental Systems is committed to continuous product development and improvement and disclaims any responsibility for technical modifications made without prior notice. Similarly, we disclaim any responsibility for the accuracy of the information and images contained in this manual.

Appendix A – Safe Use of the Device

INTRODUCTION

Portable device for detecting methane gas leaks. Used to detect leaks in meters, connections, or distribution networks, and for personnel safety.

INSTALLATION

Suitability of the device for the installation site:

When used in potentially explosive atmospheres, it is necessary to verify that the detector type is suitable for the zone classification and the flammable substances present in the system. Essential safety requirements for explosion risks in hazardous areas are defined by European directives 2014/34/UE (equipment) and 1999/92/CE of December 16, 1999 (installations). Zone classification criteria for explosive risk areas are explained in standard EN60079-10. Technical requirements for electrical installations in hazardous areas are defined in standard EN60079-14.

The instrument's label, in addition to functional data, also includes a reference to the notified body responsible for certification.

Other Precautions:

Battery charging must be performed in a safe location with the appropriate AC adapter. Opening the instrument by unauthorized personnel is prohibited, as it would invalidate the certification.

TESTS AND MAINTENANCE

Checks and maintenance of certified equipment must be carried out according to the criteria of standard EN60079-17.

REPAIR

In case of malfunction or damage, it is recommended to send the equipment to QED Environmental Systems or an authorized service distributor for repair.

Remarks:

a) Group IIC devices are suitable for IIA and IIB environments.

b) T4 temperature class devices are also suitable for all higher temperature classes (T3, T2, T1).

Appendix B – Important Information for Correct Disposal of Electrical and Electronic Equipment

At the end of its life, the product must not be disposed of with urban waste. It should be deposited in a selective collection center for municipal waste or with a retailer offering this service. Selective disposal of household appliances helps avoid adverse environmental and health consequences from improper disposal and allows for the valorization of their components, thus enabling significant energy and resource savings. To remind users of the need to dispose of electrical appliances separately, the product is marked with a crossed-out wheeled bin (see illustration).

For European users:

For disposal of electrical or electronic equipment, contact your retailer or supplier for further information.

Information on disposal in countries outside the EU:

This symbol is used only in the EU. For disposal, contact local authorities for information.