Crowcon Flamgard-Plus Инструкции - Страница 2

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1.3 Status Indication

Flamgard Plus includes a local display and status LED, visible through the

junction box window. This is shown in Diagram 1.

The display shows the current flammable gas concentration in the

range 0-100%LEL and current mode of operation ie NORMAL, ZERO or CAL.

The LED shows the current alarm state of the detector. This is summarised in

Table 1.

Operational

LED

4-20mA

state

indication

outputs*

Normal

Steady green

4 to 7.2mA

operation

Normal

Steady red

7.2 to 10.4mA

operation

(Alarm 1)

Normal

Flashing red

10.4 to 20mA

operation

(Alarm 2)

Over-range

Flashing red

24mA (clamp)

Zero/calibration Flashing green

Configuration

mode

dependent

(see section 2)

Detector

Steady amber

0mA

fault

*As standard, AL1 = 20%LEL and AL2 = 40%LEL

Relay version only

Table 1: LED status indicator summary.

2. DETECTOR CONFIGURATION

2.1 Standard configuration

As standard, Flamgard-Plus is factory set as follows:

Current source with 0 mA

2 mA

4-20 mA = Normal operation

24 mA

AL1 relay

Alarm level 1 set to 20%LEL

Normally de-energised, energising on alarm

Contact normally open (NO), closing on alarm

AL2 relay

Alarm level 2 set to 40%LEL

Normally de-energised, energising on alarm

Contact normally open (NO), opening on alarm

FAULT relay

Normally energised, de-energising on fault

Contact normally closed (NC), opening on fault

Alarm/fault relays automatically reset when alarm or fault has cleared.

INHIBIT

Normally selected. ie. when CAL/ZERO selected

current output is forced to 2mA and relays are held in

normal/no alarm state.

Location of links are shown in Diagram 2.

2.2 4-20mA options

To change current source output to sink, set switch to 'SK' position.

To change Inhibit from 2 mA to 4 mA, fit link to '4' position.

2.3 Relay options

To change AL1 or AL2 relay from NO to NC, fit link in the 'NC' position.

To change FAULT relay from NC to NO, fit link in the 'NO' position.

2.4 Inhibit options

To not inhibit 4-20 mA signal and relays, fit link to 'N' and link to '4'.

Relay

Comment*

states*

AL1 - Off

0 to 20% LEL

AL2 - Off

FAULT - On

AL1 - On

20 to 40% LEL

AL2 - Off

FAULT - On

AL1 - On

40 to 100% LEL

AL2 - On

FAULT - On

AL1 - On

>100% LEL

AL2 - On

Display back-

FAULT - On

light flashes

Configuration

Latched until

dependent

reset via 'MENU'

(see section 2)

AL1 - Off

AL2 - Off

FAULT - Off

= Fault

= Inhibit ie. Zero/Cal mode

= Over-range clamp

3. INSTALLATION

WARNING

Flamgard Plus is designed for use in Zone 1 and 2 hazardous areas and

is certified EEx d IIC T6 (AEx d IIC T6 in USA). Installation must be in

accordance with the recognised standards of the appropriate authority

in the country concerned. For more information contact Crowcon.

Prior to carrying out any work ensure local regulations and site

procedures are followed.

3.1 Location

There are no rules which dictate the siting and location of detectors, however,

considerable guidance is available from BS6959:1988 – 'British Standard

Code of Practice for the Selection, Installation, Use and Maintenance of

Apparatus for the Detection and Measurement of Combustible Gases'. In the

USA refer to the National Electrical Code (NEC 1999). Similar international

codes of practice may be used where applicable. In addition certain regulatory

bodies publish specifications giving minimum gas detection requirements for

specific applications.

The detector should be mounted where the gas is most likely to be

present. The following points should be noted when locating flammable gas

detectors:

• To detect gases which are lighter than air e.g. methane, detectors should

be mounted at high level and Crowcon recommend the use of a Collector

Cone, Part No. C01051.

• To detect heavier than air gases e.g. butane, detectors should be mounted

at low level.

• When locating detectors consider the possible damage caused by natural

events e.g. rain or flooding. For detectors mounted outdoors Crowcon

recommend the use of a Weatherproof Cap, Part No. C01442.

• Consider ease of access for functional testing and servicing.

• Consider how the escaping gas may behave due to natural or forced air

currents. Mount detectors in ventilation ducts if appropriate.

• Consider the process conditions. Butane is normally heavier than air, but if

released from a process line which is at an elevated temperature and/or

under pressure the gas may rise rather than fall.

The placement of detectors should be determined following advice of

experts having specialist knowledge of gas dispersion, the plant processing

equipment as well as safety and engineering issues. The agreement reached

on the locations of sensors should be recorded. Crowcon would be

pleased to assist in the selection and siting of gas detectors.

3.2 Mounting

The mounting detail of Flamgard Plus is given in Diagram 1. Flamgard Plus

should be installed at the designated location with the detector pointing down.

This ensures that dust or water will not collect on the sinter and stop gas

entering the detector.

3.3 Cabling Requirement

Cabling to Flamgard Plus must be in accordance with the recognised

standards of the appropriate authority in the country concerned and meet the

electrical requirements of the detector. Crowcon recommend the use of steel

wire armoured (SWA) cable and suitable explosion proof glands must be

used. Alternative cabling techniques, such as steel conduit, may be

acceptable provided appropriate standards are met.

Flamgard Plus requires a dc supply of 10-30 V at up to 210 mA.

Ensure the minimum dc supply of 10 V is observed at the detector, taking into

account the voltage drop due to cable resistance.

For example, a nominal dc supply at the control panel of 24 V has a

guaranteed minimum supply of 18V. The maximum voltage drop

allowed is therefore 8V. Flamgard Plus can demand up to 210 mA and so the

maximum loop resistance allowed is 38 Ohms. A 1.5 mm

allow cable runs up to 1500 m. Table 2 shows maximum cable distances

given typical cable parameters.

cable will typically