Operation
Switching on
When it is powered the GL-CO-RFG does not start detecting immediately and does not signal any alarm for the first two minutes of operation.
This is the time necessary for the gas-sensing elements to become stabilised so that their readout can be considered accurate and reliable. This
period for the stabilisation of the sensors is indicated, on the facia of the detector by the flashing of the FAULT and ALARM LEDs. At the end of the
stabilisation period the FAULT and ALARM LEDs, in normal situations, switch off.
Pre-alarm and alarm thresholds for methane and propane-LPG)
By means of the SENSITIVITY knob, the intervention threshold (sensitivity) can be increased or decreased according to the particular conditions of
the space in which the sensor is positioned, or for specific requirements:
Knob towards + = increase of sensitivity.
Knob towards - = decrease of sensitivity.
These adjustments, however, remain within the limits required by the regulations so it is always possible to intervene under conditions of the
maximum safety.
The intervention levels, referred to the LEL (Lower limit of Explosivity) = volumetric ratio in air of combustible gas or vapour below which an
explosive mixture is not formed) for the gases methane and propane LPG are as follows (the threshold values with the “SENSITIVITY” knob = 0 are
shown in bold type):
Pre-alarm and alarm threshold for carbon monoxide (CO)
The danger of carbon monoxide (CO) does not derive from its inflammability or the danger of explosion, but from its very high toxicity to the
human body. Moreover, its danger does not depend only on the concentration of the gas in air, but also on the length of time a person has
remained in an atmosphere in which this gas is present.
The pre-alarm and alarm levels of the sensor are determined by the processing of a microprocessor which takes into account the concentration of
the gas in the air and the exposure time. For this reason the “Sensitivity” knob on the detector must not influence the sensor readout and, even if
there is only one carbon monoxide (CO) sensor, it must be set in “0” position.
If the pre-alarm threshold is exceeded, this is indicated, on the detector facia, by the intermittent lighting of the ALARM LED for the sensor which
has detected the anomaly.
The intervention modes of the detector are accordingly as follows:
Concentration < 0.005% (50 ppm): the safety of the persons is guaranteed for an indefinite length of time and so the detector does not
intervene,
Concentration 0.005...0.01% (50...100 ppm): within this concentration range, for 60 minutes the detector signals a “Pre-alarm” situation
and after this period switches to “Alarm”.
Concentration 0.01...0.03% (100...300 ppm): within this concentration range, for 10 minutes the detector signals a “Pre-alarm” situation
and after this period switches to “Alarm”.
Concentration > 0.03% (300 ppm): the safety of the persons present in the space is not guaranteed.
The detector immediately switches to the “Alarm” state. The concentration values and times taken into consideration by the detector
have been established allowing a large safety margin to ensure there is no danger to the persons.
The action of the detector is of the “Dynamic” type: if the concentration passes from one level to another, the time calculated increases or
decreases as a consequence, thereby modifying the response of the detector. In particular, should the concentration of carbon monoxide (CO)
return below 0.005% (50 ppm) for more than one minute, the detector returns to the “Normal” condition, cancelling all the times counted up to
that moment and, if it has been programmed “Without latching” any “Alarm” condition will be terminated.
