Forbes Marshall CODEL TunnelTech205 User manual

Issue : B
Rev. : 1
Date : 11/07/22
Ref. : 100042
OPERATING MANUAL
TunnelTech205
Tunnel Atmosphere
Air Quality Monitor for NO2
CODEL International Ltd.
Unit 4 , Station Road, Bakewell, Derbyshire DE45 1GE United Kingdom
t : [phone] f : [phone] e : c[email protected] web : www.codel.co.uk

Issue : B
Rev. : 1
Date : 11/07/22
Ref. : 100042

Technical Manual CODEL
Issue : B
Rev. : 1
Date : 11/07/22
Ref. : 100042
CODEL International Ltd is a UK company based
in the heart of the Peak District National Park at
Bakewell, Derbyshire. The company specialises in
the design and manufacture of high-technology
instrumentation for the monitoring of combustion
processes and atmospheric pollutant emissions.
The constant search for new products and existing
product improvement keeps CODEL one step
ahead. With a simple strategy, to design well-
engineered, rugged, reliable equipment, capable
of continuous operation over long periods with
minimal maintenance, CODEL has set standards
both for itself and for the rest of the industry.
All development and design work is carried out ‘in-
house’ by experienced engineers using proven
state-of-the-art CAD and software development
techniques, while stringent assembly and test
procedures ensure that the highest standards of
product quality, synonymous with the CODEL
name, are maintained.
High priority is placed upon customer support.
CODEL’s dedicated team of field and service
engineers will assist with any application problem
to ensure that the best possible use is derived from
investment in CODEL quality products.
If you require any further information about
CODEL or its products, please contact us using
one of the numbers below or alternatively visit our
web site.
t : [phone]
f : [phone]
e : [email protected]
web : www.codel.co.uk
Over the past 15 years CODEL tunnel sensors have
been supplied to more than 400 road and rail tunnels
throughout the world. Our impressive reference list
includes Eurotunnel (France), Mont Blanc Tunnel
(France), Dartford Tunnel (UK), Lane Cove Tunnel
(Australia), Snow Mountain Tunnel (Taiwan) and the
SMART Tunnel in Malaysia, plus many others
throughout China, Italy, Switzerland and South
Korea placing CODEL as a world leader in tunnel
atmosphere monitoring.
CODEL’s tunnel sensor range is further extended by
additional sensors for the measurement of CO, NO,
Visibility and Wind Speed and Direction.
Additional product data sheets: TunnelCraft III Air
Quality Monitor for the Measurement of Carbon
Monoxide, Nitric Oxide & Visibility & TunnelCraft III
Air Flow Monitor for the Measurement of Tunnel Air
Speed & Direction, are available to download from
our web site: www.codel.co.uk.

Technical Manual CODEL
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Rev. : 1
Date : 11/07/22
Ref. : 100042

Technical Manual CODEL
Issue : B
Rev. : 1
Date : 11/07/22
Ref. : 100042
1. Air Quality Monitor for NO2 1
2. Principles of Operation 3
2.1. Air Quality Monitor (AQM) ............................................................................................................................3
2.1.1. NO2 Measurement................................................................................................................................3
3. Specifications 6
3.1. General...................................................................................................................................................6
3.2. Air Quality Monitor –NO2.......................................................................................................................6
3.3. Tunnel Display Unit (TDU) .....................................................................................................................6
3.4. Power Supply Unit (PSU).......................................................................................................................6
4. Basic Equipment Supply 7
4.1. Standard Supplied Items..............................................................................................................................7
4.2. Customer Supplied Items.............................................................................................................................7
5. Installation 8
5.1. Check the Equipment...................................................................................................................................8
5.1.1. NO2 Air Quality Monitor........................................................................................................................8
5.1.2. Power Supply Unit (PSU)......................................................................................................................8
5.1.3. Tunnel Display Unit (TDU)....................................................................................................................9
5.2. Connections..........................................................................................................................................10
5.2.1. Connection schedule, (for AQM & TDU up to 100m apart).........................................................10
5.2.2. Connection Schedule J-Box configuration 1, (for AQM & TDU up to 1km apart)........................11
5.2.3. Connection Schedule J-Box configuration 2, (for AQM & TDU up to 200m apart) .....................12
6. TDU Operation 13
6.1. Introduction.................................................................................................................................................14
6.1.1. Measurement ......................................................................................................................................14
6.1.2. Calibration...........................................................................................................................................14
6.2. Normal Start-Up Procedure........................................................................................................................14
6.3. Modes of Operation....................................................................................................................................14
6.4. Key Operation.............................................................................................................................................15
6.5. Program Tree .............................................................................................................................................16
6.6. Operating Mode..........................................................................................................................................16
6.7. Parameter Mode (Mode 2) .........................................................................................................................17
6.7.1. Identification........................................................................................................................................17
6.7.2. Output..................................................................................................................................................17
6.7.3. Alarm...................................................................................................................................................17
6.7.4. Clock ...................................................................................................................................................17
6.7.5. Auto Cal...............................................................................................................................................17
6.8. Chamber.....................................................................................................................................................18
6.9. Diagnostic Mode (Mode 4) .........................................................................................................................18
6.9.1. Temperature........................................................................................................................................19
6.9.2. Y & Z Values .......................................................................................................................................19
6.9.3. NO2 Values.........................................................................................................................................19
6.9.4. Calibration Data ..................................................................................................................................19

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6.10. Set-Up Mode (Mode 5).............................................................................................................................21
6.10.1. Security Code Entry..........................................................................................................................21
6.10.2. Configure O/P 1 & 2..........................................................................................................................22
6.10.3. Alarms...............................................................................................................................................25
5.2.4.6.10.4. Parameters.........................................................................................................................25
6.10.5. Identity...............................................................................................................................................26
6.10.6. Protocol.............................................................................................................................................26
6.10.7. Baud Rate .........................................................................................................................................26
6.10.8. Set Clock...........................................................................................................................................26
6.10.9. Calibrate............................................................................................................................................26
7. Commissioning 29
7.1. AQM (NO2).................................................................................................................................................29
7.1.1. Communications (see also Appendix A for further information) .........................................................29
7.1.2. Heater Control.....................................................................................................................................29
7.1.3. Alignment ............................................................................................................................................29
7.1.4. Gain Adjustment..................................................................................................................................29
7.1.5. Calibration NO2...................................................................................................................................30
8. Maintenance 31
8.1. General.......................................................................................................................................................31
8.2. Emergency Shutdown/Isolation Procedure................................................................................................31
9. Data Communication 32
9.1. Hardware Configuration .............................................................................................................................32
9.1.1. System ................................................................................................................................................32
9.1.2. Processor Architecture........................................................................................................................32
9.2. Address Numbers.......................................................................................................................................33
9.2.1. AQM Address......................................................................................................................................33
9.2.2. TDU Address.......................................................................................................................................33
10. List of Figures 34
Appendix A : Standard MODBUS Communication with CODEL NO2 TDU 35

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IMPORTANT
The warning signs (and meanings) shown below, are used throughout these instructions and are intended to
ensure your safety while carrying out installation, operation and maintenance procedures. Please read these
instructions fully before proceeding.
Caution, risk of electric shock.
Caution, risk of danger.
Caution, hot surface.
Earth (ground) terminal.
Protective conductor terminal

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1.
Air Quality Monitor for NO2
NO2 is produced naturally by the combustion processes within the internal combustion engine and is emitted from
the tail pipes of all types of vehicles. NO2 is also particularly toxic and prolonged exposure to levels as low as a
few hundred parts per billion will have a detrimental effect on human health. There is a growing international
requirement to measure and limit the levels of NO2 within road tunnels to reduce the exposure of tunnel users to
this toxic gas.
Previous attempts to continuously measure NO2 levels in tunnels have failed due to either insufficient accuracy
of measurement or too great a complexity and cost of the measuring instrument, resulting in unacceptable levels
of maintenance and measurement availability.
The CODEL NO2 Air Quality Monitor resolves these issues by means of a very simple but accurate measurement.
The CODEL sensor is a precision transmissometer which measures the attenuation of blue light by NO2 in the
tunnel atmosphere. The light source is a simple LED and the interfering effects of particulates in the atmosphere
are eliminated by making the measurement within a 1m diffusion cell into which the atmospheric gases, but not
the particulates, can freely diffuse.
The result is a very accurate and stable sensor having no moving components and requiring no maintenance
throughout its lifetime. Even the optics remain clean because they are contained within the diffusion cell which
prevents the deposition of dirt on the optical surfaces. The filters through which the gas diffuses do not become
blocked because the diffusion process exerts no pressure on particulates to force them into the filter pores.
Fully configurable analogue and alarm outputs are generated inside the Tunnel Display Unit (TDU). In addition
there is an RS485 output that can be utilised to deliver MODBUS protocol to a SCADA system located in the
tunnel control centre.
The NO2 Air Quality Monitor system arrangement is illustrated in Figure 1.

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Figure 1: System Arrangement

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2.
Principles of Operation
2.1.
Air Quality Monitor (AQM)
2.1.1.
NO2 Measurement
2.1.1.1.
Measurement Principles
By measuring the amount of blue light absorption along a specific measurement path the concentration of NO2 in
that path can be determined. It is important to minimise the impact that interfering absorption elements will have
on the measurement. Absorption by solid particulate matter suspended in the atmosphere is eliminated by
enclosing the measurement light beam within a measurement cell into which only gases can diffuse. The NO2
monitor utilises a Single Wavelength Optical Transmissometer (SWOT) technique.
2.1.1.2.
Measurement Elements
An LED is employed as the light source. It is mounted behind a lens that focuses the light down the 1m-long
measurement cell (see Figure 2) to a reflecting mirror and back to a single receiving lens that focuses the light
onto a silicon photocell detector. The sensor microprocessor switches the LED on and off to modulate the light at
a frequency of 10,000Hz. An additional silicon detector is used to measure the brightness of the transmitted LED
light.
Figure 2: AQM Measurement Elements
①
LED Source
②
Detector
③
1 Meter Measurement Cell
④
Stainless-Steel Diffusers
⑤
Reflector
⑤
③
①
④
②

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A parameter, ‘Y’(blue) is defined, which is a measure of the light attenuation of the blue light beam, thus:
‘Y’(blue) = 90,000 - (set cal) x DRblue/DTblue
where: DRblue is the received detector signal for the blue light channel.
DTblue is the detector signal from the transmitted blue light.
The set cal value is the calibration constant required to set the ‘Y’(blue) value to 10,000 when the
NO2 concentration is zero.
NO2 concentration is derived from the relationship:
NO2 = Kb x [‘Y’(blue) - 10,000]
The constant Kb is a factory-set value that is used to calibrate the analyser response to NO2 in ppb.
Because of the extreme sensitivity of the measurement it is necessary for the LEDs and detectors to be held at a
constant temperature to eliminate drifts due to temperature. This is achieved by heating the internal metal block
which contains all these elements and accurately controlling its temperature.
2.1.1.3.
Diffusion Cell
Because light will be absorbed and scattered by solid particulate matter suspended in the tunnel atmosphere it is
essential that the measurement of NO2 is made over a measurement path free from such particles. This is
achieved by enclosing the optical beams within a 1m-long stainless-steel sample chamber. Rows of stainless-
steel sintered filters mounted along the wall of this chamber allow atmospheric gases to diffuse quickly into the
chamber while restricting totally the passage of solid particulates. The gas transfer is by a diffusion process and
there is no suction force pulling the gases or the particulates into the sintered filters. The filters do not therefore
become blocked with solid deposits in the filter pores and the system can remain operational for many years
without the need to clean the filters.
2.1.1.4.
Diagnostic Data
Every second, a complete measurement is determined for each of the detector levels and a refresh of the NO2
measured level is made. Diagnostic data for each of the detector values, the ‘Y’(blue) values along with
temperature control data is available as diagnostic data through the TDU.
2.1.1.5.
Periodic Calibration
The measurement of NO2 is required typically in the range 0 to 2ppm. This device is accurate to +/-40ppb. When
calibrating analysers such as CO or NO in tunnels a zero level can often be produced by over-ventilating to flush
the tunnel with ambient air that always contains less than 1ppm of CO and NO. This solution is not possible with
NO2 sensors measuring in the range to 1ppm. Normal atmosphere levels can contain 100ppb or more of NO2. In
city centre locations this could rise to 200 or 300ppb. An accurate zero level necessary to calibrate the analyser
must be achieved by injecting nitrogen into the calibration port of the sensor enabling the measurement chamber
to be flooded with nitrogen to obtain a true zero calibration.
A span check will require a zero calibration to be performed with nitrogen being injected into the inlet port of the
diffusion cell. The span can then be checked either by injecting a low concentration (typically 1ppm) of NO2 in N2
directly into the diffusion cell or by injecting typically 150ppm of NO2 in N2 into a low-volume flow-through cell
mounted in the reflector end of the diffusion cell. Of the two alternative span-check methods the flow-through cell
method is preferred as it consumes much less gas.
Because of the potential safety hazards of leaving pressurised gas cylinders in tunnels, using bottled N2 for
automatic zero calibration is not generally acceptable.
A compromise solution is to assume a general background level of atmospheric NO2, say 100ppb, and under
normal clear tunnel conditions calibrate the sensor to read this background level without the need for nitrogen
zero calibration cylinders.

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Zero calibration may be configured to be activated:
- Manually - from the TDU keypad
- Automatically - from the TDU clock (up to 1 week intervals)
- Remotely - from the TDU logic input (volt-free contact input into +PS/0PS terminals

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3.
Specifications
3.1. General
Construction
corrosion resistant polyester-coated aluminium housings sealed to IP67
(AQM); IP66 (PSU & TDU)
Electro-magnetic immunity
shielded to comply with 73/23/EEC - low voltage and 89/336/EEC-EMC
Ambient temperature
-20oC to +50oC
3.2. Air Quality Monitor –NO2
Monitoring channels
NO2
Measurement path
2m (folded to 1m)
Measuring range (standard)
0 to 2000ppb, other ranges selectable on set-up
Accuracy
+/- 40ppb
Power
48V DC, 36VA obtained from local data bus from TDU
Communication
local data bus
Dimensions (mm)
Ø180 x 1130mm (see Figure 3)
3.3. Tunnel Display Unit (TDU)
Display
32-character back-lit alpha-numeric display with soft-touch keypad
Outputs
Analogue:
2 x 4-20mA, 200V, common mode isolation, max.
load 500
Contact:
3 x volt-free contacts SPCO, 50V, 1A
local data bus
RS485:
commissioning software or standard MODBUS
Power
48V DC, 12VA
Dimensions (mm)
160 x 160 x 90mm
3.4. Power Supply Unit (PSU)
Outputs
48V DC fused (maximum current output must not exceed 2.6A @ 125W)
Power
85 to 264V AC, 47/63Hz, 230VA maximum
Dimensions
200 x 230 x 110mm

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4.
Basic Equipment Supply
4.1.
Standard Supplied Items
CODEL will supply the following equipment:
-NO2 Air Quality Monitor(s) each fully assembled with diffusion tube and reflector with flow-
through cell and fitted with :
1 x 4-core interconnecting cable (5m) between the AQM and the junction box
-1 x 2-core interconnecting cable between the AQM reflector and the junction box
-1 x Junction box for each AQM (to IP66 specification), suitable for 6-core cables and complete
with 3 x cable glands
-2 x Mounting brackets per AQM
-1 x Power Supply Unit per AQM
-1 x Tunnel Display Unit per AQM
-Cable glands for each PSU & TDU
4.2.
Customer Supplied Items
The customer will supply the following equipment:
-Alarm/analogue cable for each AQM
-1 x 4-core interconnecting cable between the TDU and the junction box
-1 x 2-core interconnecting cable between the PSU and the junction box
-Suitable mounting bolts for each AQM, PSU & TDU

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5.
Installation
WARNING! Be sure to observe all necessary safety precautions at all times during installation.
5.1.
Check the Equipment
After unpacking the equipment check that all items are present using the packing list provided.
5.1.1.
NO2 Air Quality Monitor
The NO2 monitor is secured horizontally to the tunnel wall using the brackets provided to support and clamp the
measurement chamber. The arrangement of the monitor together with mounting-hole details are shown in Figure
3.
Figure 3 : Air Quality Monitor –NO2
5.1.2.
Power Supply Unit (PSU)
Mount the PSU to the tunnel wall using 4 x M6 bolts (customer supply).
Figure 4 : Power Supply Unit
600
1130
4 holes (in each flange) 10.5 dia
on 168 pcd for M10 bolts

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To mount the PSU first remove the cover by loosening the four captive screws. Secure the case to a firm support
by use of the four mounting holes, one in each corner. Since the mounting holes are located outside the seal of
the case it is not necessary to seal the mounting holes after installation, nor is it necessary to remove the circuitry
from the case for installation.
If commissioning is not to be carried out immediately reattach the lid to the unit.
5.1.3.
Tunnel Display Unit (TDU)
The TDU may be mounted close to the NO2 monitor or up to 1km distant, but consideration should be given to
the method of connection in relation to the separation distance –see Figure 9 and Figure 11. Where the TDU &
AQM are separated by up to 500m then the 48V supply may be connected directly into the TDU using 1.5mm2
overall conductor core cable. If the TDU & AQM are more than 500m apart (up to 1km) then the 48V supply should
be connected into the junction box and the PSU mounted near to the AQM.
Figure 5 : Data Display Unit
To mount the TDU first remove the cover by loosening the four captive screws. Secure the case to a firm support
by use of the four mounting holes, one in each corner. Since the mounting holes are located outside the seal of
the case it is not necessary to seal the mounting holes after installation, nor is it necessary to remove the circuitry
from the case for installation.
If commissioning is not to be carried out immediately reattach the lid to the unit.

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5.2.
Connections
WARNING Wiring should only be undertaken by a qualified technician.
The following diagrams illustrate the connections for the equipment.
NOTE: Only use the O/P 3 and 4, 1Amp outputs connections on the PSU.
5.2.1. Connection schedule, (for AQM & TDU up to 100m apart)
Figure 6: Connection Schedule
Figure 7: Connection Without Junction Box
RS485
4 –20mA
Mains power
48V DC
TDU
PSU
AQM
Transceiver
Heated mirror

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If the DDU is to be mounted apart from the sensor probe at a distance greater than 100m, then it is necessary to
use a junction box due to voltage drop over long cable distances.
5.2.2. Connection Schedule J-Box configuration 1, (for AQM & TDU up to 1km apart)
Figure 8 : J-Box Connection Schedule, Config 1
Figure 9: J-box Connection Diagram
RS485
4 –20mA
Mains power
48V DC
Junction Box
TDU
PSU
AQM
Transceiver
Heated mirror

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5.2.3. Connection Schedule J-Box configuration 2, (for AQM & TDU up to 200m apart)
Figure 10: J-Box Connection Schedule, Config 2
Figure 11 : Alternative J-box Connection Diagram
RS485
4 –20mA
Mains power
48V DC
Junction Box
TDU
PSU
AQM
Transceiver
Heated mirror