Oldham MX42A User Manual

INSTALLATION AND OPERATING

MANUAL

Réf.: NPM42GB

GAS DETECTION

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CONTENT

1 DESCRIPTION (fig 1) ..................................................................................................7

2. INSTALLATION AND CONNECTIONS .......................................................................9

2.1. Installation .............................................................................................................9

2.2. Electrical connection of the MX 42A detection unit (fig 2)......................................9

2.3. Connection of the detection unit to the detectors ..................................................9

2.3.1. Physical layout of detectors............................................................................9

2.3.2 Type and connection of detectors (fig 3)......................................................11

2.4. Connection of the detection unit to external devices ...........................................13

2.4.1. Connection to servocontrols.........................................................................13

2.4.2. 4-20 mA current output.................................................................................13

3. START-UP AND OPERATION...................................................................................15

4. CONFIGURATION OF ALARMS AND SERVOCONTROL .......................................17

4.1. Characteristics of alarm triggering.......................................................................17

4.2. Programming of parameters................................................................................20

4.3. Servocontrol ........................................................................................................23

4.3.1. Relays ..........................................................................................................23

4.3.2. 4-20 mA current output.................................................................................23

5. PERIODIC SERVICING..............................................................................................25

5.1. Adjustment of detectors from the MX 42A detection unit.....................................25

5.2. Local adjustment at the detectors........................................................................26

6. TROUBLESHOOTING...............................................................................................27

7. DETAILED TECHNICAL CHARACTERISTICS.........................................................28

7.1. Casing.................................................................................................................28

7.2. Display.................................................................................................................28

7.3. Power supply.......................................................................................................28

7.4. Measurement inputs............................................................................................29

7.5. Alarm...................................................................................................................29

7.6. Control functions..................................................................................................30

7.7. Relaying ..............................................................................................................30

7.8. Output of measurements.....................................................................................30

8. Scrapping of mx42a..................................................................................................31

9. LIST OF MX42A SPARE PARTS...............................................................................31

9.1. Spare parts..........................................................................................................31

9.2. Intrinsic barriers and accessories........................................................................ 31

10. Special Specifications for use in Potentially Explosive Atmospheres in

accordance with European Directive ATEX 94/9/EC.....................................................32

10.1. Specifications for mechanical and electrical installation in Classified Areas....32

10.2. Metrological Specifications...............................................................................32

10.3. Connecting detectors other than INDUSTRIAL SCIENTIFIC detectors to the

MX42A device................................................................................................................33

10.3.1. Device transfer curves in 0% to 100% LEL configuration.........................33

10.3.2. Device transfer curves in 0% to 30.0% OXYGEN configuration ...............34

10.3.3. Power supply and load resistance characteristics ....................................34

10.4. MARKING.......................................................................................................34

Figure 1

1 DESCRIPTION (fig 1)

The MX 42A detection unit is an apparatus for the detection and measurement of various combustible, toxic or oxygen-carrying gases.

The MX 42A detection unit has 4 independent measuring channels. Each channel is connected to a gas detector located in places to be monitored. The measurement from the detector is displayed on the MX 42A detection unit and compared to alarm thresholds. Should alarm thresholds be exceeded, the MX 42A detection unit actuates relays which can be used for the control of outside devices (horn, telephone call, exhaust fans, etc.).

Note: the detection unit also comes in a 2-measuring channel version.

Main characteristics: (cf Figure 1)

- Casing for wall mounting made of PVC (length: 340, height: 300, depth: 107) with intern "plating".

- AC or DC power supply

- 4 measuring inputs for detectors of the explosimetric, toxic or oxygen type (or other type on request)

- Visualization of the measurement by LCD

- Alarms per channel:

 2 increasing or decreasing thresholds, manual or automatic clearance (control logic

of exhaust fans on programming)

 1 increasing or decreasing threshold, automatic clearance, triggering on basis of time

or on averaging

- Relaying: a total of 10 relays distributed as follows:

 2 relays per channel (NO or NC) for the first two alarm thresholds  1 relay common to the channels for the third alarm threshold (or the remote

transmission of the alarm on programming)

 1 relay common to the channels for detector faults and anomalies

- 4-20 mA output per channel (< 1 mA for fault, 2 mA for maintenance)

- Resettable buzzer should alarms or an anomaly appear

Figure 2

2. INSTALLATION AND CONNECTIONS

Please ensure you read the paragraph: Special Specifications for use in Potentially Explosive Atmospheres in Accordance with European Directive ATEX 94/9/EC

2.1. Installation

The detection unit can be installed in any place without an explosive atmosphere. It should be put in a well ventilated place where it can be watched (guard house, control room, security service...).

It is attached according to Figure 2: 4 attachment points, marked 1, 2, 3 and 4, with centres of 314 x 245 mm, using 5 mm screw.

Caution: So that the cover of the detection unit can be completely opened, there must be at least 30 cm of free space above it.

Before installation, switch off the MX42A with the switch located on the inside (bottom left corner).

2.2. Electrical connection of the MX 42A detection unit (fig 2).

Power supply: connect the power supply wires to the terminal blocks of the detection unit.

- Earth, live and neutral terminals, 220 V AC (207 V to 244 V), 50/60 Hz, protected by an F1 630 mA time-delay fuse.

- or + DC, - DC terminals, 24 V (19 V to 32 V), DC protected by an F2 4A fuse.

On option

A sticker on the casing gives the power supply voltages.

Their location depends on three m

- either 115 V AC (103 V to 122 V), 50/60 Hz, protected by an F1 1.25 A time-delay fuse

- or 48 V (43 V to 60 V), protected by an F3 2 A time-delay fuse

2.3. Connection of the detection unit to the detectors

2.3.1. Physical layout of detectors

ain factors:

- Density of gas to be detected: in elevation for gases lighter than air and low down for gases heavier than air

- Leak point: determination of the probable source of a leak

- In the flow of air in ventilated rooms.

Transmitters 4.20 mA / 2 wires.

Explosimetric transmitters (catalytic celles) with 3 wires

Figure 3

4.20 mA /3 wires for flammable gas transmitters

4.20 mA / 2 wires / transmitters for parking CO detection

2.3.2 Type and connection of detectors (fig 3).

3 types of detectors are to be differentiated:

- Explosimetric detectors of the BRIDGE type (no integrated electronics, 3 connecting wires of an armoured cable).

Resistance of detection unit - detector cable: maximum 8 ohms per wire (length 500 m, cable 3 x 1.5 mm²), or 16 ohms in a loop.

- Explosimetric detectors of the 4-20 mA type (a shielded cable with 3 wires of an armoured cable).

Resistance of detection unit - detector cable: maximum 16 ohms per wire (length 1 km,

cable 3 x 1.5 mm²), or 32 ohms in a loop.

- Toxic gas or oxygen detectors of 4-20 mA type (a shielded cable with 2 wires).

Resistance of detection unit - detector cable: maximum 16 ohms per wire (length 1 km,

cable 3 x 1.5 mm²), or 32 ohms in loop.

It is specified that

 detectors are connected by SHIELDED CABLES  using shielded cables is compulsory  the screen of shielded cables must be connected to the earth at two

extremities (detectors and control unit)

 connections to the earth are considered as equipotential.

a) Parking garage application

Toxic gas detectors "Co-parking" type can be mounted in parallel in the event that it is necessary to obtain an average gas concentration. It is absolutely essential that the detectors be located in the same area. A max of, five detectors can be connected in parallel.

Connection of the Zener barrier

The Figure 4 describes the connection between the detector and the barrier

Figure 4

"i"

transmitters

Figure 5

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