4
GAS LEAK DETECTORS
Expected working life of the sensor is 10 years; in this connection, the PC board of the leak detectors is provided
with a built-in memory which activates a flashing yellow LED upon reaching 10 years of operation, to indicate that
it is advisable to replace the detector (the internal sensitive element is liable to natural aging; its sensitivity is
increased accordingly, hence always to the advantage of safety).
Moreover the memory allows checking, if returning the unit to the factory, the serial N°, running hours, the number
of times the leak detector has entered alarm condition, etc.
The “Gas Sentinel” gas leak detectors are provided
with a programming and silencing button plus a series
of LEDs signalling the operating status of the detector :
Programming button:
Service button, located under the adhesive label, can
be activated by hand. It allows:
1) Access to the programming menu and setting the
gas leak detector operating parameters.
2) Silencing the buzzer for 1 minute in case of alarm.
LEDs :
Under normal operating conditions, the LEDs are in the following configuration :
1) Green LED: power,
- if lit up, it indicates that the gas leak detector is switched on.
- if unlit, it indicates that the gas leak detector is off,
- if flashing, it indicates that the programming procedure is activated.
2) Yellow LED: malfunction. Unlit under normal operating conditions.
3) Red LED: alarm 10% LEL. Unlit under normal operating conditions.
Red LED: alarm 15% LEL. Unlit under normal operating conditions.
Self-diagnostics
The electronic circuit of the gas leak detectors is provided with a self-diagnostics program which continuously
monitors operation of the gas leak detector: any malfunction, critical fault on the sensor or main components, is
indicated via a visual signal (yellow LED). In this case, the gas leak detector should be sent to the factory for
checking.
Setting
The gas leak detector is factory-set with 2 different alarm thresholds, namely: 10% and 15% of the LEL and leaves
the factory set to 10% of the LEL. If the user has too many false alarms (e.g. generated by products such as
bleach, wine, etc.), he can select the 15% alarm mode (however always at a value lower than the max. one
prescribed by regulations - 20%).
When the gas leak detector is set for mode of operation based on 10% LEL and the gas concentration exceeds
this threshold, a prealarm is displayed (first red LED flashing); if the concentration of gas remains for more than
30 seconds, the leak detector enters the alarm status:
• steady red LED,
• buzzer activated,
• relay switched.
Likewise in the case of the gas leak detector set to 15% LEL, if the gas concentration exceeds this threshold, a
first prealarm is displayed (2nd red LED flashing); the leak detector then passes to the alarm status only when the
concentration of 15% LEL is exceeded for more than 30 seconds (2nd red LED steady).
Red 2° setting alarm threshold (15% LEL)
Normally switched off, if switched on alarm
condition
Red 1° setting alarm threshold (10% LEL)
Normally switched off, if switched on alarm
condition
Yellow Fault
If switched on, malfunction or broken
signal
Green Power
Always switched on normally functioning
Service button
Allowed to programming and silencing alarm (1 min).
Warm-up of the sensor element :
Gas Sentinel has a warm-up time of 2.5 minutes starting from the powering of the gas leak detector, during which
the LEDs light up in rotation and the leak detector is not activated. This is the time required for bringing the sensor
to its operating temperature which is 140°C.
