Sensitron S2398CO, Instruction Manual

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ENGLISH
Pag. 11
1. Introduction
SMART P gas detectors are used to detect the presence of combustible (%LFL) and toxic
(ppm) gases in non classified areas. It has been especially designed and tested according
to the European Standard EN 50545-1 for carbon monoxide, nitrogen dioxide and petrol
vapours detection in underground car park applications.
The catalytic sensor employed for the detection of flammable compounds offers a great
precision and selectivity, thus avoiding false alarms. The electrochemical cells employed for
the detection of toxic gases allow the measurement of toxic compounds at very low con-
centrations.
SMART P gas detectors provide a serial RS485 output. To check the detector’s calibration use
the calibration keypad STS/CKD+ or STS/CKD-OLED.
To protect and increase the stability and accuracy of the gas detector, the microprocessor
present on the internal electric circuit board, is programmed with the following software
algorithms:
³
Self diagnostic procedure to control the detector main operational parts, both hard-
ware and sensing element.
³
Zero point tracking to maintain the zero parameter of the sensor apart from possible
drifts due to thermal or physical variations of the sensor.
³
Digital filter employed in the digital analysis of the analogue values sampled. It is de-
signed to prevent the effects of transients, which may cause instability or incorrect
readings with possible false alarms.
³
Hysteresis cycle applied to the digital outputs to eliminate continuous switching close
to the preset alarm thresholds.
³
Watch-dog for the microprocessor control. In case of intervention, the RS485 output
communication will be interrupted, while the red LED stops blinking and remains on.
1.1 Gas detectors identification
Table 1) SMART P gas detectors
Code Gas Fullscale Sensing element
S2398CO CO 0-300 ppm Electrochemical cell
S2399ND NO2 0-20 ppm Electrochemical cell
S2400CO-ND CO and NO2 0-300 ppm CO
0-30 ppm NO2
Electrochemical cell
S2400CO-VB CO and Petrol
Vapours (VB)
0-300 ppm CO
0-100% LFL VB
Electrochemical cell and Catalytic sensor