HUBERG METREX2 User Manual

1.0 General Description

The METREX2 is a digital gas detection instrument used for systematic survey of natural and town gas networks, and for leak detection both inside and outside buildings. Its compact design and modest size allow for easy transportation. The large LCD display provides instantaneous readings of gas concentrations, making it simple to operate. Various probe types can be selected, enabling use in difficult-to-reach areas.

A microprocessor manages all instrument functions, including sensor control for gas concentration detection, keyboard commands, alarm management, data registration, and serial communication for downloading data to a PC. The unit is designed to comply with the ATEX directive.

The METREX2 operates with rechargeable nickel metal hydride batteries, providing at least 8 hours of autonomy on a full charge under normal working conditions and a constant temperature of 20 °C. Recharging batteries and I/O connections must be performed in safe environments.

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

2.0 Keyboard and Connections

The METREX2 features the following controls and connections:

1. OFF Button: Powers the instrument off.
2. Data Recording Button: Initiates data recording.
3. ON/OFF Acoustic Signal Button: Controls the acoustic signal.
4. PPM/VOL/LEL Button: Switches between measurement ranges.
5. Auto Zeroing Button: Resets the instrument to zero.
6. 220V~ Connection LED: Indicates connection to power supply.
7. Battery Recharge LED: Indicates battery charging status.
8. ON/OFF Acoustic Signal LED: Indicates the status of the acoustic signal.
9. Alarm Threshold LED: Indicates alarm threshold status.
10. % VOL Scale LED: Indicates when the % VOL scale is active.
11. Display: Shows measurement readings and instrument status.

Figure 2: Connections

1. Air outlet
2. Quick coupling for probes
3. Buzzer
4. Socket for battery charger/serial port for data download
5. Cover

3.0 Instrument Performance

3.1 How to Switch On Instrument

To switch on the instrument, press one of the buttons (2, 3, 4, or 5) on the lower right of the keyboard for at least three seconds. Upon activation, the instrument's serial number will appear on the display, followed by an acoustic signal. The display will then show the software version (e.g., "Px.x") and "CAL" (indicating calibration in progress). The warming-up and auto-calibration phase takes approximately 1 minute. After completion, the device automatically switches to the PPM scale. ATTENTION: Switching on the instrument must be done in a gas-free area.

3.2 PPM and VOL Measuring Ranges

The METREX2 offers two measurement scales: PPM and %Vol. After switching on, the instrument defaults to the PPM range, displaying concentrations from 0 to 9900 PPM. The volumetric scale measures from 0 to 100%.

A changeover between the PPM and %Vol ranges can be achieved by pressing the PPM/VOL button (4). If a concentration of 1% Vol occurs while in the PPM range, the instrument automatically switches to the volumetric range. To switch back from volumetric to PPM, the PPM/VOL button must be pressed manually. This automatic switch-back is only possible if the gas concentration is below 10000 ppm (1%). When the volumetric range is selected, the corresponding LED (10) is illuminated.

3.3 LEL Measuring Range

The LEL scale is activated by pressing the PPM/VOL button (4) for more than 2 seconds. An acoustic signal tone is emitted if the acoustic alarm is active. Switching from the LEL scale back to PPM or %Vol requires a brief press of the same button.

For CH4, the LEL measuring range (0-100%) corresponds to a range of 0-5% (%Vol). (100% LEL = 5% Vol).

3.4 Alarm

Upon switching on the METREX2, the acoustic alarm is activated, and the LED (fig.11) is lit. The user can deactivate or reactivate the acoustic alarm by pressing the alarm ON/OFF button (3). If the acoustic alarm is deactivated, the optical alarm LED (9) will blink if the measured concentration exceeds the preset alarm limit.

Alarm thresholds are adjustable for both PPM and %Vol ranges. Pressing button (3) for over 2 seconds displays the current alarm limit. This limit can be adjusted by holding button (3) and pressing the PPM/VOL button (4) to increase the value, or the zero-button (5) to decrease it. It is recommended to verify the desired display mode after adjusting the alarm limit, as button (3) also controls the acoustic alarm.

3.5 Data Registration (Optional)

The METREX2 can record up to 500 measurement readings in its internal memory. Pressing the record button (2) during normal operation freezes the current displayed value. The displayed value will blink, and an acoustic signal will sound, indicating the special status. The pump is also switched off. The instrument remains in this mode until another button is pressed. Pressing button (2) again shows the number of the last saved measurement. Pressing buttons (4) or (5) allows scrolling through saved readings forward or backward. Holding a button pressed for at least 2 seconds displays the reading. To return to normal function without saving data, press button (3).

To cancel all records, connect the METREX2 to the battery charger and power supply. Press buttons (2) and (5) simultaneously for at least 2 seconds. The instrument will emit an acoustic signal and display "cancellation" (fig.17) to confirm.

3.6 Auto Zeroing

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

3.7 Display Illumination

To activate or deactivate the background display illumination, press buttons (3) and (5) simultaneously.

3.8 Recharging of Batteries

IMPORTANT: Only use the HUBERG battery charger supplied with the METREX2. Ensure the instrument is switched off before connecting the charger to a 220V power supply and plugging it into the METREX2's socket (4). The instrument automatically recognizes the connection and enters recharging mode. The charging voltage is displayed during the process. This procedure must be carried out in a safe environment.

Two LEDs indicate the status: one for power supply connection (fig.20) and one for battery charging (fig.21). The charging LED blinks fast during charging and slowly when fully charged. Recharging takes approximately 10 to 12 hours.

3.9 Battery Status Visualization

The battery status is shown at the bottom left of the screen. The instrument monitors battery voltage, and when the battery is low, the battery icon appears "empty". A "low battery" status indicates approximately 10 minutes of operation remaining. After this period, the METREX2 will stop, and "STOP" will appear on the display (fig.22). The instrument must then be recharged.

During charging, the display shows "Load" (fig.23). Full recharge after complete discharge takes 10-12 hours.

4.0 Gas Type Selection (Optional)

In addition to CH4 calibration, the METREX2 can be optionally provided with GPL and/or City Gas calibrations. Users can switch gas types during normal operation after self-calibration. To switch gas type, simultaneously press keys (4) and (5) (fig.1, fig.26, fig.27). The display will briefly show the new gas type. The METREX2 is then ready to measure the new gas.

When the METREX2 is turned on, the display shows the current gas setting: CH4, C3H8, or Nothing (CIT).

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

5.0 Pump Block

The METREX2 may feature an optional pump blocking function. If a continuous flux obstruction occurs (for approximately 4 seconds), the METREX2 stops measuring, and "Poff" is displayed (fig.28). To resume measurement, press any of the four keys below the display (fig.1 keys 2, 3, 4, 5).

6.0 Maintenance and Periodical Calibration

For accurate functioning and reliable measurement readings, QED Environmental Systems recommends annual service and calibration of the METREX2 by QED Environmental Systems or an authorized service distributor. A certificate of calibration, conforming to ISO standards, will be issued upon completion of checks and adjustments. QED Environmental Systems recommends regular control with the HANDYGAS instrument, depending on the frequency of use.

For more information, refer to "8.0 Accessories" and the Technical Datasheet on HANDYGAS.

7.0 Warranty

The METREX2 is covered by a guarantee against production defects according to legal norms. QED Environmental Systems provides repairs for malfunctions due to manufacturing defects during this period. The guarantee is void for damages caused by improper use or handling. Warranty is terminated if unauthorized personnel perform repairs. This guarantee is valid in all countries where QED Environmental Systems or its authorized agents distribute the METREX2. QED Environmental Systems offers no warranty on calibration.

IMPORTANT: Read the instructions carefully before use. No guarantee is valid if the device is not handled according to the instructions in this manual. QED Environmental Systems is available for any further information regarding use and maintenance.

PLEASE NOTE: QED Environmental Systems is committed to product development and improvement and accepts no liability for technical modifications made without notice. Similarly, no responsibility is taken for the accuracy of information and images in this manual.

Appendix A – Safe Use of the Instrument

Introduction

The METREX2 is a portable instrument for gas leak detection of methane, used for searching leaks in meters, connections, and distribution networks, as well as for personal safety.

Installation

Suitability of Equipment into Installation Site

When used in areas with explosion risk, verify that the detector type is suitable for the area classification and the flammable substances present. Essential safety requirements for explosion risk in dangerous areas are established by European Directive 2014/34/EU (equipment) and 1999/92/CE (facilities). Explosion risk area classification criteria are detailed in norm EN60079-10, and technical requirements for electrical installations in dangerous areas are in EN60079-14.

The instrument's label includes functional data and references to the notified body responsible for certification.

Other Precautions for Usage

Battery charging must be performed in a safe place using the appropriate external adapter.
Do not open the instrument by unauthorized personnel, as this will invalidate the certification.

Testing and Maintenance

Checks and maintenance of certified equipment should be performed 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.

Appendix B - Important Information for Correct Disposal of the Electric and Electronic Equipment

At the end of its working life, the product must not be disposed of as urban waste. It should be taken to a designated local authority waste collection center or to a dealer providing this service. Separate disposal of household appliances avoids potential negative environmental consequences from improper disposal and allows for the recovery of constituent materials, leading to significant energy and resource savings. The product is marked with a crossed-out wheeled dustbin to remind users of the need for separate disposal.

For European users: For disposal of electrical or electronic devices, contact your retailer or supplier for more information.

Information on Disposal in Outer EU Countries: This symbol is used only in the EU. For disposal outside the EU, contact the local authority for information.