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IST-ST441EC
AVVERTENZA: La "Calibrazione" va eseguita esclusivamente in aria pulita (ambiente senza la presenza di gas
CO o altri gas inquinanti) e usando solo la miscela Gas CO a 300 ppm in azoto.
1) Dopo aver eseguito il "Codice Calibrazione", il Led Verde inizierà a lampeggiare.
2) Attendere che il Led Giallo si accenda fisso.
3) Infilare (tenerlo appoggiato) il TC011 sul porta-sensore e regolare l'afflusso del Gas (300ppm CO+Azoto), in modo
che il flussometro indichi circa 0,3 l/min
4) Attendere circa 3 minuti, poi, quando il Led Verde si accende fisso (e mentre è ACCESO fisso), premere il tasto
F2 e tenerlo premuto finché i due Led non rimangono spenti. (AVVERTENZA: se il Verde che continua a lam-
peggiare oltre 5/6 minuti la calibrazione è fallita. Spegnere e accendere il rilevatore, dopo il preriscaldo, ripetere
la procedura di "Calibrazione". Verificare che il problema non dipenda dal gas o dal flusso instabile. Se la condi-
zione persiste, sarà necessario sostituire il rilevatore e/o inviarlo al fornitore per la riparazione).
5) Chiudere la bombola e rimuovere il TC011. A questo punto si possono verificare due casi:
Led Giallo e Verde spenti: la calibrazione è avvenuta correttamente, dopo 8 secondi automaticamente il rilevato-
re si spegne e si riavvia in funzionamento normale (vedi capitolo FUNZIONAMENTO " Preriscaldo").
Solo Led Giallo Acceso: la calibrazione è fallita. In questo caso, dopo 8 secondi il rilevatore si riavvia automati-
camente e dopo il preriscaldo, ripetere la procedura di "Calibrazione" senza reinserire il "Codice". Se la condizione
persiste, sarà necessario sostituire il rilevatore e/o inviarlo al fornitore per la riparazione.
EN
GENERAL INFORMATION
The ST441EC is a Carbon monoxide (CO) gas detectors with electrochemical sensor, used in gas alarm sys-
tems for car parks, heating plants, and environments to be protected from possible leaks of CO (It is not suitable for
industrial environments). The detector has a three-wire 4÷20mA linear output signal (S) with full scale 300 ppm CO
(part per million). The instruments comprise of a thermoplastic
nection terminals
are
mounted; the sensor is placed in the yellow sensor holder on the housing cover.
installation and the protection code is IP44
The ST441EC is normally connected to our gas control units for heating plants, as shown in the
NOTES ON THE DETECTED GAS
ST441EC has a sensor that can detect Carbon monoxide (CO) gas which is a poisonous, colourless, odourless,
and tasteless. CO is a little lighter than air (its density as to air is 0.97) and it is also flammable but at very high con-
centrations, in fact its LEL (Lower Explosive Limit) is 10.9%v/v (%volume). His TWA is 25 ppm (Time-Weighted Average)
and STEL is 35 ppm (Short Term Exposure Limit).
CO is produced by incomplete burning of carbon-based fuels, including gas, oil, wood and coal. It is only when the
fuel does not burn properly that excess CO is produced, which is poisonous. When CO enters the body, it prevents
the blood from bringing oxygen to cells, tissues, and organs.
OPERATIONAL DESCRIPTION
The electrochemical sensor is temperature compensated, but is sensitive to extreme humidity variations. The cali-
bration is carried out with specific gas to be detected (CO). Anyway, it can contemporaneously detect other gases
that should be present in the same environment as listed in
On the PCB (printed circuit board placed inside the housing cover) there are two F1 e F2 keys, using for the Test
and Calibration routine, protected by a code, and 2 LEDs shows the operating conditions:
Green LED "ON":
Yellow LED "FAULT":
Preheating: when the detector is powered, a pre-heating time of about 60 seconds begins, indicated by the
flashing of the yellow "FAULT" LED and during this time the output remains at 4 mA.
After this period, the green LED "ON" illuminates to indicate normal functioning. After this period the unit is able to
detect gas even if it attains the optimum stability conditions after about 4 hours continual functioning.
Afterwards it is advisable to check in clean air that the output is about "4 mA" (0 ppm on the control unit to which the detec-
tor is connected) and only if necessary, proceed to "Zero Adjust" as indicated in FUNTIONAL TESTING / ZERO ADJUST.
Normal operation: the green LED "ON" should be light on.
Faults: In case of sensor damage, the "S" output falls down to 0 mA (FAULT). The signal will then be interpreted by
the control unit and reported as a fault situation.
The Yellow LED lights up every 4 seconds (with the Green LED on): to warn that the Sensor has exceeded its life
limit (about 5 years) and the correct operation is no longer guaranteed. The detector continues to operate, but it is
necessary, as soon as possible, to replace it with a new one.
If the Yellow LED is on and the Green is off it indicates more possibilities of fault:
1) If 0mA Output indicates that the "Sensor" is faulty, it will be necessary to replace and/or send the detector to
the supplier for repair.
2) If the Output is > 24mA indicates, or the "Sensor" fault, or a gas concentration higher than 375 ppm. If there is
no gas and the condition does not change, it will be necessary to replace and/or send the detector to the sup-
plier for repair.
Periodical testing: The verification with CO/Nitrogen gas mixture is the only safe method to check the effective
operation of the detector and the correct response to the CO gas.
It is recommended to perform the functional check every 12 months and if necessary also proceed with the Cali-
bration with CO/Nitrogen gas mixture as explained later in the
GECA S.r.l. - Via E. Fermi, 98 25064 Gussago (Brescia) Italy
Istruzione / User's Manual / Manuel d'utilisation
(vedi
Fig.3).
normal operating condition.
the sensor should be faulty, disconnected, out of scale or expired.
housing, in which the
table
4.
paragraph FUNTIONAL
TESTING.
Tel. +39 030 3730218 - Fax +39 030 3730228
Pag. 4 / 10
electronic
circuit and the con-
It is for wall
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