BGX701-240-R01 Liberty gas EG4v12 user cum maintenance manual Page 9 of 32
side, at the front. Provision is also made for front/battery cover ‘open’ detection. Removal of the cover and
access to the battery compartment requires breaking the plastic seals and undoing the screws.
3.1.1 Electronic unit (EU)
The electronic unit (EU) is fitted on the front of the mechanical gas meter using mounting studs. The
enclosure has an ingress rating of IP-54. The EU houses the processor and battery.
Figure 3: Electronic unit with the cover removed
Functions of the EU
● Computes the volume of gas passed through the gas meter, processes and stores the information in
its memory and communicates the information to mobile app over Bluetooth (on request).
● Carries out all accounting and billing activities for gas consumption
● Detects and records flags of tamper events/faults
● Monitors battery voltage for detection of low battery condition
The EU generates a ‘low battery’ alert when the battery voltage is continuously below 3.3 volts for 48
hours. In the case of battery failure, the EU will close the gas meter valve, stop metrology and all
communications as well as take backups of all registers.
3.1.2 Battery
A 3.6 V D-Cell battery provides power to the EU. The battery is fitted in a small compartment inside the EU
and has an independent cover with cover removal detection and a tamper-evident sealing arrangement.
Under normal operating conditions, the battery is expected to last for approx ten years. The hardware and
firmware in the EU is designed to work with low power consumption to conserve battery life.
3.1.3 Integral shut-off valve
The meter has an integrated supply shut-off valve mounted inside the metal meter enclosure. The EU can be
factory configured to close the valve when it detects any of the following events:
a) Battery cover open detection
b) Magnet tamper detection
c) Tilt detection
3.1.4 Tamper detection
The meter has anti-tamper features including tilt sensor, magnetic tamper sensor and battery cover open
sensor.
3.2 Using the display
The figure below shows the illuminated segments during display test when key 0 is pressed:
EU front cover/battery open sensor
Replaceable battery
Self-tapping screws
Metrology seal
Self-tapping screws
Mounting studs
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