IGD 2-Wire Systems Assembly instructions

2-WIRE SYSTEMS
2 - W i r e G a s D e t e c t i o n S y s t e m I n s t a l l e r s G u i d e V 4 . 5 1
Triton House
Crosby Street
Stockport
SK2 6SH
England
Tel: [phone]
Fax: [phone]
Email: [email protected]
Website: www.internationalgasdetectors.com
Addressable
2-Wire
FS646773
REF: T550-INST V4.51
EMS696504

1
2-WIRE
GAS DETECTION
www.internationalgasdetectors.com
Display
&
Volt Free
Relay
Analogue in
Analogue in
Sounder
Output
Digital Out
Digital Out
or
or
Gas
Gas
Detector
Detector
Each Detector Node Has Multiple I/O
ALL
OK
First Fit Cabling
Fit Detector Nodes
Fit Additional Devices
Where You Need Them
Safety Assured
CO H2S LPG
4-20
Addressable
2-Wire
HUB
APP Based Setup and Service Tools
No Specific Cable Type
No Cable Polarity
2 Core Cable Connects Detector Nodes
350 Detector Nodes/Devices Possible
Communicate over 3000M Possible
Cascade Hubs or Control Panels
Modbus and Bacnet Compatible
BlueTooth
Ethernet
USB
Battery Backup
FS646773

2
Interaction Between the Gas Detection System and Other Systems
Clear Indication to workers That a Gas Hazard Exists and the Action They Must Take
All Gas Detectors shipped from IGD are pre-calibrated. It is not always necessary to re-calibrate a
newly installed system on site but it is recommended that commissioning is undertaken.
Commissioning should be undertaken by persons trained to do so. Commissioning should ensure that
the system performs and interfaces correctly to all connected devices, host systems and operates to
the required cause and effect.
Failure to follow this installers guide could compromise operation of the 2-Wire gas detection system
so please follow the enclosed information carefully.
A competent person is someone who has sufficient training and experience or knowledge and other
qualities that allow them to assist you properly. The level of competence required will depend on the
complexity of the situation and the particular help you need.
IGD’s gas detection systems are capable of installation by electrical installation engineers. Design of
a system is not covered in this guide and should be undertaken by a competent person. The design
should include:
IGD can provide help to design systems where help is required and can also provide training for
surveyors, specifiers, designers and installers.
This installers guide is intended for the use of system specifiers, surveyors, designers and installers.
The intention of this guide is to provide information for the correct installation of IGD’s range of 2-Wire
gas detection systems. This guide indicates correct cabling practice, types of cabling which can be
used and options available to correctly design and install a 2-wire gas detection system. This guide is
not intended as a design or specification guide, these are available separately.
Note that System control panels, detector nodes, battery backup modules and power boosters are all
supplied with their own manuals. Their general specifications and performances are available both in
their individual manuals and published data sheets. This data is not reproduced in this guide.
The Nature of the Gas Hazard and Appropriate Placement of Detectors
The Necessary Safe Operating Procedures That Must be in Place
IGD are available to answer question using our on-line ticketing system available through our website.
NOTE that ATEX equipment has specific requirements for cable protection and glanding to housings.
These requirements are detailed in manuals for such equipment available through our website.
Systems should be designed and installed by competent persons. A competent person being defined
by the UK Health and Safety Executive as:
Introduction

3
SECTION 1
MOUNTING DETAILS FOR EQUIPMENT

4
Tocsin 750 Physical
Installation Cables
FRONT VIEW
382mm
292mm
72mm
120.5mm
134mm
20mm
48.5mm
Front Face
Top Face
Side Face
56.5mm
30mm
10 off 20mm
Cable Entries
360mm
Supported Installation Cables 2 Core 1.5mmSQ or 2.5mmSQ See IGD Cable System Calculator
Typically SWA, MICC, FP200, SY, CY, H03VVH2-F Mains Cable Screened, screened or Similar
Note 150W and 24V DC Versions Can be
Flush mounted into walls up to the front face flange
300W Versions have active ventilation and must be
surface mounted allowing 100mm clearance all round
Note that the rear case can be rotated to allow
20mm entries to face either up or down
Addressable
2-Wire

5
TOCSIN 650 PHYSICAL
Installation Cables
FRONT VIEW
382mm
292mm
72mm
120.5mm
134mm
20mm
48.5mm
Front Face
Top Face
Side Face
56.5mm
30mm
10 off 20mm
Cable Entries
360mm
Supported Installation Cables 2 Core 1.5mmSQ or 2.5mmSQ See IGD Cable System Calculator
Typically SWA, MICC, FP200, SY, CY, H03VVH2-F Mains Cable Screened, screened or Similar
Addressable
2-Wire
Note 150W and 24V DC Versions Can be
Flush mounted into walls up to the front face flange
300W Versions have active ventilation and must be
surface mounted allowing 100mm clearance all round
Note that the rear case can be rotated to allow
20mm entries to face either up or down

6
Mounting Details and Dimensions Safe Area Versions
Gas Detector Types
Mounting Details and Dimensions ATEX Versions
172
158
76
48
43
86
98 18
5
20mm Entries Top, Bottom & Either Side
Note TOC-750-AN3 Shown
Detectors, Annunciators and
Nodes Share Common
Mounting Details
145.0
126.0 128.5
COVER SECURING SCREW
M20 x 1.5
40.0
25.0
Ø7.0
EXTERNAL EARTH
MKIII FLAMMABLE
GAS DETECTOR
SHOWN
40.0
Ø110
128.0
The ATEX version uses IGD’s JB3 series ATEX EXD terminal enclosure. Please note that cable glanding
and sealing must conform to ATEX requirements which is more fully described in the ATEX JB3 manual
Relative response to Methane @ 4.4% Vol = 100% LEL Equivalent to 55% LEL N-Butane
Refer to individual data sheets for specific data relevant to available gas detectors, types,
accuracies and sensitivities available.
For pellistor type gas detectors complying to BS EN 60079-29-0 and 1, these general purpose
flammable gas detectors are suitable for Methane and LPG detection in the range 0-100% LEL.

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FRONT VIEW
382mm
292mm
72mm
120.5mm
134mm
20mm
48.5mm
Front Face
Bottom Face
Side Face
56.5mm
30mm
10 off 20mm
Cable Entries
360mm
Battery Backup Modules
TOC-750-BAT1 7AH Battery Backup with 150W PSU
TOC-750-BAT2 17AH Battery Backup with 300W PSU
460mm
292mm
115mm
20mm
Front Face
Bottom Face
Side Face
25mm
60mm
95mm
4 off 20mm
Cable Entries

8
SECTION 2
SITING GAS DETECTORS

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Gas detectors usually fall into two groups for placement
Each site should be surveyed and assessed on its own merits. This document presents general
guidance only.
1. Plant Protection. Typically flammable gas detectors fall into this category. Aside from asphyxiation
flammable gases are typically not directly toxic and so detectors are placed strategically where the gas is
expected to accumulate based on its relative density to air (lighter or heavier)
Note that in many cases both life safety and plant protection sensors may be appropriate on a site. For
example a plant using liquid helium may have plant protection sensors at high level to ventilate roof
spaces in the event of leaks. However in the event of ventilation failure Helium could accumulate down
towards the zone where personnel operate. In this case a second set of life safety sensors would be
appropriate.
2. Life Safety Systems. Here the concern is that a toxic or asphyxiant gas is directly hazardous to
personnel and so the gas detection is placed based on the normal operating zone for the people present
Lighter than air gases, detectors placed at highest ceiling points
Consider fitting collector cones at lower level for gas bottle stores
boiler plant and gas meters (see separate application note).
400mm
1000mm
1800mm
Life Safety Zone
Consider ceiling divisions, follow rules for smoke detectors
Methane, Helium, Hydrogen, Ammonia etc
LPG, CO2
CO, CO2, O2
H2S, NO2, NO
HCN, HCL, HF
NH3 etc
Consider fitting splash/dust guards to protect low level sensors
Consider sensors in under floor areas/voids/drains where heavier than air gases are present
LPG 0-100%LEL
SN:20235-1-1 ADD:4110
GAS DETECTOR
LPG 0-100%LEL
SN:20235-1-1 ADD:4110
GAS DETECTOR
Siting Gas Detectors

10
High Concentrations Local to Release Source or Cloud Development Scenario
5M
100%
CO2
For this CO2 Example Expect Higher Concentrations at Low Levels. Use for Ventilation Trigger and
Pre-Alarms
For this CO2 Example use Detectors in the Life Safety Zone to Trigger Ventilation and Evacuation Alarms
5M is a Maximum Detection Distance and Will be Effected by Topography.
Gas Levels Will Drop as Distance to Leak Source Increases Requiring Lower Alarm
Set Points
Siting Gas Detectors
Heavier Than
Air Gases Can Show a Gradient in Room Levels With Higher Concentrations at Floor Level or Slow Leak Scenario
This Example Illustrating A CO2 Gas Release From
A Storage Cylinder. Typical
Scenario, Broken or Blown off Hose, Regulator Incorrectly
Connected, Ruptured Gauge or Similar.

11
Area Coverage for Gas Detectors
Cryogenic Gas Detection
Calibration and service Requirements for Gas Detection Systems
Typically up to 75 SQ M Coverage
In a similar manner to smoke detectors, a gas detector can provide up to 75SQ M area coverage based on
a 5M radius of operation. There are many factors affecting this, geometry of a room, equipment in the area,
gas characteristics, ventilation air flows etc. IGD can support throughout the survey, design and installation
process to ensure the best possible result on site.
Applications involving Cryogenically cooled gases such as liquid Nitrogen or Helium need careful
consideration for gas detection. On initial release as cryogenically cooled gases can typically be at lower
temperature and high density than their surroundings they will behave differently than when in their
gaseous state. In such cases it should be considered if two sets of detection is required, one for the life
safety zone and one for low level detection in the gases cooled state. Applications involving such gases
are recommended to be surveyed.
All gas detection systems require regular checking and calibration to be in compliance with the UK
factories act. The service and calibration period will be a function of the application based on
environmental in service conditions. It is extremely important to ensure a service plan is in place for any
gas detection system installed as part of a site safety system. IGD can work with operators to provide
advice, service and spares to ensure an appropriate level of cover.
Max 5M Radius

12
General Detector Mounting Positions Atex (BS EN 60079-29-1)
General Detector Mounting Positions Safe Area (BS EN 50194)
Detectors should be
mounted vertically with the
sensor face facing
downwards to protect from
contamination.
Sensor Facing Down
Sensor Mounted to Vertical Wall in Various Orientations
Do NOT Mount With The Sensor Facing Upwards

13
Detectors in Airflows Mounting Positions Atex (BS EN 60079-29-1)
Do NOT mount Detectors Where
Airflows Are Likely to be Directed
either onto or Away From the Sensor
Face. This Situation May Result in
Contamination and/or reduced
Detection Capability
Air Flows up to 6M/S Are
Allowable Without Any
Performance Issue Across
the front of The Sensor Face
Air Flows up to 1M/S Are Allowable Without Any Performance Issue
Detectors in Airflows Mounting Positions Safe Area (BS EN 50194)

14
Siting System Components
Consider the use of mimic panels, HMI panels or GSM options available
from IGD to provide additional remote indication/alarm
Control Panels:
These should be located outside of the area protected by its connected
gas detectors.
The control panel should be accessible such that in the event of an
alarm the area can be evacuated and gas levels viewed from the
controller.
As a general rule if there is gas detection fitted to an area then there
should be an audio-visual alarm (beacon sounder) to alert personnel
who may be in the same area. Typically these will be standard beacon
sounders where the sounder can be silenced from the control panel
once an alarm is accepted. Standard LED beacon sounder modules are
available from IGD and can be run from addressable I/O points to
minimise cabling. Another option is to fit IGD’s range of annunciators.
Audio-Visual alarms
Annunciators are addressable devices typically fitted at door entry
points. They provide a clear audible visual alarm in the event of a gas
alarm to warn persons from entering an area where a gas hazard could
be present.
They offer many advantages over standard beacon sounders. They can
be fitted to standard dado trunking systems; cannot be confused with
other alarms; the displayed alarm message and flashing colour display is
unambiguous; they can be fitted with slam switches.
Annunciators
Gas Collector Cones and splash Guards
For detectors fitted at low level, fitting splash guards may be appropriate
to protect sensors from dust, rain splash, floor washing etc.
Where detectors are located above gas plant such as boilers or meters in
rooms with high ceilings then consider the use of gas collector cones.
These are fitted to detectors sited just above gas plant to enhance the
detectors capability to detect gas leaks (see separate application note)

15
SECTION 3
GENERAL CABLING PRINCIPLES
CABLE TYPES
AND
CABLE SIZING

16
Cable Type Guidance
L1 L1
L2
L2
Cable Screens direct to
commoning blocks provided
CY Style Cable
Recommended Cable Preparation
FP Style Cable (Preferred Option)
SWA Style Cable
CY Type cable has a braided screen which should be trimmed
back to ensure no trimmed conductor ends up on sensitive
PCB components, tracks or terminals where it may short. The
screens of the incoming cables should be terminated to the
floating terminal block provided to ensure screen continuity.
Trim back any unused conductors and ensure the braid is
insulated with heat shrink or insulation tape and/or sleeve.
Unused
L1
L2
Unused
L1
L2
Drain Wire Screen
FP style cable is fitted with a foil screen and drain wire. Generally this is easier to terminate than
CY type cable. Trim back any unused cores and foil screen. Ensure the drain wire is insulated
with suitable size sleeving and terminates to the cable screen terminal
SWA style cables are usually only recommended for used with ATEX EXD housings where the
universal cable glands ground the cable armour to the housing. This provides both an effective
EMC screen and mechanical protection. Ensure unused conductors are trimmed back and
isolated. If terminating to plastic enclosures fit ‘pan handles’ and terminate on the outside of the
enclosure to ensure screen continuity
IGD’s 2-Wire gas detection systems operate using screened cabling of appropriate cross sectional
area. There are no specific requirements and our typical advised cable types are indicated below.
Cable screens, either foil and drain wire, braid or armouring must be continuous between devices and
grounded for effective operation. Ancillary devices such as stop buttons, beacons, sounders etc should
commoned to the earth blocks provided as indicated below.
Strip Conductors 7mm Ensure No Stray
Strands

17
Main Base PCB Connectors
When unplugging detectors from the main PCB DO NOT lever them off. This will potentially cause
damage to the PCB and/or connector mating parts and invalidate any warranty. If it is necessary
to remove the PCB connectors use long nose pliers.
Note that connectors can be plugged either
vertically or Horizontally to the PCB

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System Example
LPG 0-100%LEL
SN:20235-1-1 ADD:4110
GAS DETECTOR
LPG 0-100%LEL
SN:20235-1-1 ADD:4110
GAS DETECTOR
Typically 1.5mmSQ
24V L1,L2
Unscreened Cable
2 Core Highway as:
Controller in Supervisors Office
ATEX Zoned Area
Mix Annunciators With Other
Addressable Devices Such as
TOC-750 Series Detectors.
Use ATEX Rated detectors
where required
Use Annunciators For Door
Entry Control.
Use Annunciators with Gas
Detector Interfaces to Detect
& Alarm in Specific Areas
Use the Detector or
Annunciator I/O
Capability to Control
Gas Supply Valves,
Beacon-Sounders or
other devices
Laboratory
Gas Bottle Store
Addressable
2-Wire
Where Required For Longer Cable Runs
or Where Device and Accessory Density
is High add Power Boosters or Cascade
Hubs to Increase Distance Capability to
up to 3KM
Cabling: When using stranded cable fit bootlace ferrules to
prevent stray wire strands shorting.
Cable glands must be used for cable entries.

19
B A 0V DC B A 0V DC
Screen B A 0V DC
RS485 Modbus
Comms Port
RS485 Modbus
Comms Port
RS485 Modbus
Comms Port
Interfacing to the Remote Modbus Port
Cable Sizing
Tocsin 650/750 Controller (slave) Tocsin 650/750 Controller (slave)
Master DCS/BMS
Note only the A,B and 0V DC Connections are
Used. 0V DC between master and slave should
be connected for correct operation and to prevent
damage to both master and slave systems
The Tocsin 750 series controllers have an in-built memory map allowing access to alarm status, panel
status, readings etc using Modbus RTU protocol. Wiring between units is as follows:
Refer to users guide for Modbus channel mapping
More than one controller can be interfaced on the same Modbus cable by
assigning individual Modbus addresses to each controller.
2
Up to 400m use minimum 1.0mm cable with an overall cable screen.
2
Cable runs over 400m use 1.5mm cable with an overall screen
Modbus
Address
100
Modbus
Address
99
Fit terminating
resistor at last
device across
A-B 120 Ohms