sensitron SMART3 NC Gas Detector Instruction Manual

sensitron SMART3 NC Gas Detector

Product Information

SMART3 NC Gas Detector

The SMART3 NC gas detector series is designed to detect the presence of combustible (%LEL) and toxic (ppm) gases in non-classified areas. The gas detector is manufactured by SensitronS.r.l. in Italy and comes with an ATEX marking and additional information label. The gas detector has a label with a serial number, adjustment thread, and year of manufacture. The gas detector can be adjusted for the detection of various gases and has multiple output types. The gas detector can be connected to a calibration keypad, display OLED, RS485 board, or 3 relay board.

Product Usage Instructions: Installation

The gas detector must be mounted with the sensing element placed downward. The enclosure should not be drilled. During installation, the user has to fix the detector with two plugs of 6×40 mm. The plugs must be positioned at a distance of 100 mm, 100 mm, and 108 mm as described in the figure.

Product Usage Instructions: Circuit Layout

The gas detector has a terminal for connections with the following layout:

• 1: +Vcc 12-24V
• 2: RS485 A
• 3: RS485 B
• 4: Gnd
• 5: +Vcc 12-24V
• 6: +/- 4-20 mA OUT

The gas detector has a dip-switch to set thresholds’ alarm and detector address. It also has a connector for the calibration keypad or display or 3 relay boards, connectors for RS485 board or 1 relay board, connectors for sensing element, and connector for the internal preamplifier. Pin 1-2 should not be used. Pin 3-4 is open for Modbus Standard communication protocol and closed for proprietary protocol typically used by Multiscan IDI version 3.00 or before. Pin 5-6 is open to enable auxiliary boards and display LEDs and closed to disable them. This manual is a short installation guide for gas detectors of the SMART3 NC series, used to detect the presence of combustible (%LEL) and toxic (ppm) gases in nonclassified areas. The reading of the main manual of the gas detector is recommended.

IDENTIFICATION LABEL

Each gas detector has a label with the serial number, adjustment gas, and other information.

Example of gas detector label to be filled

MAIN MANUAL LINKS

• Technical manual for SMART3 NC gas detectors

ACCESSORIES MANUAL LINKS

INSTALLATION SITE PREARRANGEMENT

At the mounting and installation phase be sure all safety precautions have been considered. Always consider how important it is the correct positioning of gas detectors to get the optimum response.

• Be careful never to install gas detectors close to air intakes or fans causing strong air currents.
• Be sure the detectors are attached to a firm base to prevent vibration that can damage them, producing unreliable results.
• Although the electronics comply with the electromagnetic compatibility rules, it is advised to keep the detectors at a distance from any radio frequency senders (such as radio links or similar).
• Please be also sure that detectors are placed in a convenient location for future maintenance and calibration requirements.
• LPG, petrol vapors, CO2, and NO2 are gases heavier than air and tend to spread downwards; the detector should be placed at 30 cm from the floor to maximize the effectiveness of the detection. CO has a specific weight similar to air; it is a very toxic gas and to get reliable protection, the detector should be placed at the breathing level, approximately 1.60m above the floor. Methane is a gas lighter than air and it tends to spread upwards; the detector should be placed at 30 cm from the ceiling in order to maximize the effectiveness of the detection.

INSTALLATION

Correct positioning mode

The gas detector is always to be mounted with the sensing element placed downward. For no reason at all the enclosure can be drilled. During the installation step, the user has to fix the detector with two plugs of 6×40 mm. The plugs must be positioned following the distances described in the following figure.

Detector circuit layout

JUMPERS PROGRAMMING FOR ALARM THRESHOLDS

• VALUES IN % FULL SCALE (ABSOLUTE VALUES FOR OXYGEN)
• ONLY USE DIP SWITCHES 3-4-5-6 TO SET ALARM THRESHOLDS
• ONLY FOR DETECTORS OF OXYGEN ENRICHMENT – DEPLETION

DIP SWITCH N.2 SELECTS THE CURRENT OUTPUT MODE

• POSIZIONE “OFF”: USCITA DOPPIA SOGLIA 10-20 mA PER CENTRALI A VARIAZIONE DI ASSORBIMENTO (LE SOGLIE OPERATIVE SONO LA 1 E LA 2).
• “OFF” POSITION: 10-20 mA CURRENT OUTPUT TO OPERATE WITH FIRE CONTROL PANELS USING A
• CURRENT/VOLTAGE CONVERSION (THE OPERATIVE THRESHOLDS ARE THE 1ST AND THE 2ND).

TESTING AND USE

Power ON
When the detector is powered on, the red LED on the motherboard starts blinking at slow intermittence. The output current is nearly 1.5 mA. After 1 minute, the red LED flash rate is equivalent to the detector working status and the output current is 4.0mA. Once the warm-up phase is over, the detector can work correctly, although the optimal performances will be achieved after two hours.

Testing
Detectors are factory calibrated for the specific gas required by the customers. Future adjustments to the preset calibration can be carried out by employing the calibration keypad. Testing should be carried out by using a gas mixture in the appropriate range, along with our calibration kit.

Use
The detector works autonomously and automatically. Once adequately connected, no further operations are required. The flashing red LED on the motherboard indicates the detector’s working condition as detailed in the main manual.

MAINTENANCE

Sensitron recommends a check of permanence through a test gas with the proper calibration kit. If the gas detector is equipped with an electrochemical cell or a pellistor sensor, the check must be biannual. With an infrared sensor, the performance checking must be annual. If required, during these tests perform the Zero and Span calibration. Moreover, Sensitron recommends performing the same tests when the detector reports a gas reading above an alarm threshold. Test results should be recorded in a suitable book to be shown to the Authority in case of inspection. For further information, refer to the kit calibration manual MT894.

Sensitron srl works for a constant improvement of its products and reserves the right to change the technical data without notice. To have the updated product characteristics check on the website www.sensitron.it or write an e-mail to sales@sensitron.it.

Contact details: SENSITRON s.r.l. Viale della Repubblica, 48 – 20007 – Cornaredo (MI) Italy TEL. +39 0293548155 – FAX +39 0293548089 – www.sensitron.it – E-mail: sales@sensitron.it.

References

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