5
G 521 - RFG 361
C1 Eng.
25.11.08 MZ
Rev. 02
We reserve the right to make changes without notice
COSTER
8.
2
.
3
Diagram of connection with N.C. valve with manual
reset (230 V~)
8.
2
.
4
Diagram of connection for control of aeration fan
(230 V~)
B – Gas detection sensor
Y3 – N.C. solenoid valve with manual reset
B – Gas detection sensor
M – Aeration fan
Typical application for detecting carbon monoxide (CO)
In garages where it is necessary to change the air, but
without acoustic alarm
9. OPERATION
9.
1
Switching on
When it is switched on the detector does not immediately sense gas and so does not signal the alarm for the first
two minutes of operation.
This is the time necessary for the gas-sensitive elements to become stabilised so that their detection can be con-
sidered correct and reliable. This stabilisation period is indicated by the flashing of the FAULT (6.
3
) and ALARM
6.
4
) LEDs on the facia of the detector. At the end of the stabilisation period the FAULT and ALARM LEDs, in nor-
mal situations, switch off.
9.
2
Pre-alarm and alarm threshold for methane and propane (LPG)
By means of the SENSITIVITY (4.
1
) knob on the detector, the intervention threshold (sensitivity) can be increased
or decreased according to particular conditions of the space in which the sensor is positioned, or for specific
requirements:
– knob t = 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 level 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):
Type of gas
LEL
Pre-alarm threshold
Alarm threshold
methane
5%
50,000 ppm
0.3...
0.5
...0.8%
3,000...
5,000
...8,000 ppm
0.5...
0.8
...1.25%
5,000...
8,000
...12,500 ppm
propane - LPG
2.1%
21,000 ppm
0.14...
0.22
...0.35%
1,400...
2,200
...3,500 ppm
0.22...
0.35
...0.56%
2,200...
3,500
...5,600 ppm
9.
3
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 extreme 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.
