CODEL Tunnel Tech 700 Series User manual

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TECHNICAL MANUAL
Tunnel Tech 700 Series
Tunnel Tech 701 - CO/NO/NO²/VIS
Tunnel Tech 702 - CO/VIS/VIS
Tunnel Tech 703 - CO/VIS
Tunnel Tech 704 –NO/VIS
Tunnel Tech 705 - NO²/VIS
Tunnel Tech 706 –CO/NO²/VIS
Tunnel Tech 707 –NO/NO²/VIS
Tunnel Tech 708 - VIS Only
Tunnel Atmosphere Monitoring System
(CO/NO/NO²/Vis)
CODEL International Ltd.
Station Building, Station Road, Bakewell, Derbyshire DE45 1GE United Kingdom
t : [phone] f : [phone] e : c[email protected].uk web : www.codel.co.uk

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Rev. : 0
Date : 25/04/17
Ref. : 100303

CODEL
Issue : A
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Date : 25/04/17
Ref. : 100303

CODEL
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Ref. : 100303
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
CODEL offices, Bakewell, Derbyshire

CODEL
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Ref. : 100303

Technical Manual CODEL
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Contents
1. System Description 1
1.1. The Tunnel Tech 700 Series Concept 1
1.2. CO, NO, NO², and Visibility Air Quality Monitor 2
1.3. Power Supply Unit (PSU) 3
2. Principles of Operation 4
2.1. Air Quality Monitor (AQM) 4
2.1.1. VisibilityMeasurement 4
2.1.2. CO. NO & NO2Measurement 6
3. Specifications 7
3.1. General 7
3.2. Power Supply Unit (PSU) 7
3.3. Air Quality Monitor 7
3.4. RS485 Interface 8
4. Installation 9
4.1. Mounting Details 9
4.1.1. Air Quality Monitor (AQM) 9
4.1.2. Power Supply Unit (PSU) 9
4.2. Connections 10
5. Commissioning 15
5.1. Power Up 15
5.2. Visibility Commissioning 15
5.2.1. Visibility Module Communication 15
5.2.2. Alignment 16
5.2.3. Detector Levels Error! Bookmark not defined.
5.2.4. Calibration Vis 18
5.3. Electrochemical Cell Commissioning 19
5.3.1. Electrochemical Cell Module Communication 19
5.3.2. Detector Levels 19
5.3.3. Electrochemical Cell Calibration 21
6. Maintenance 22
6.1. Routine Maintenance 22
6.1.1. Visibility 22
6.1.2. Electrochemical Cell Calibration 23
6.1.3. Electrochemical Cell Replacement 24
6.1.4. Part Numbers & Replacement List 26
6.1.5. Optional Parts 26
7. Data Communication 28
7.1. Hardware Configuration 28
7.1.1. System 28

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7.2. Address Numbers 29
8. List of Figures 30
Appendix 1 : MODBUS Communication & RS485 Connection 31
Appendix 2 : Optional Tunnel Display Unit (TDU) 34
Appendix 3: Optional Heated Mirrors arrangement & connection 35

Technical Manual CODEL
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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

Technical Manual CODEL
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1
1.
System Description
1.1.
The Tunnel Tech 700 Series Concept
Tunnel Tech 700 Series is an all-new tunnel atmosphere monitoring system designed exclusively for
road tunnel applications. It offers a family of monitors that provide all the essential measurements
necessary to monitor a tunnel atmosphere for:
- Carbon Monoxide
- Nitric Oxide
- Visibility
- Nitrogen dioxide
This is achieved by using a modular design concept so that the users’ precise monitoring
requirements can be satisfied with a minimum number of components, minimum tunnel cabling and
minimum installation costs. It also offers a variety of data outputs to enable simple acquisition of data.

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The monitoring stations, Figure 1, provide all required measurements and outputs at each monitoring
location within the tunnel.
Figure 1 : Tunnel Tech 700 Series - Monitoring Station
1.2.
CO, NO, NO², and Visibility Air Quality Monitor
The Air Quality Monitor (AQM), shown in Figure 2, uses visible light channels to measure visibility and
electrochemical cells. The AQM consists of a transceiver that projects visible beams to a reflector unit
mounted 3m away.
A high-powered modulated LED is used for the visible light source.
Optical visibility is measured by a silicon photo-detector that determines the attenuation of the light
beam, along the instrument sight path, due to the particulates in the tunnel atmosphere.
CO, NO and NO2 are measured using electrochemical cell technology. Once the zero level of the cell
is set and recorded in the instrument memory, the cell output is linear and proportional to the ppm or
ppb reading.
A serial data link via an RS485 interface allows communication directly with the AQM sensors.
CO/NO/NO²/VIS Air Quality
Monitor

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Figure 2 : Tunnel Tech 700 Series –CO/NO/NO²/Vis air quality monitor
1.3.
Power Supply Unit (PSU)
The PSU is required to convert the mains (90-263V AC) supply to the 12V or 24V DC required to
power the AQM.
Figure 3 : Tunnel Tech 700 Series - power supply units 12V DC & 24V DC
DC outputs
12V DC
24V DC
mains input
connections
DC outputs

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2.
Principles of Operation
2.1.
Air Quality Monitor (AQM)
2.1.1.
Visibility Measurement
2.1.1.1.
Transmissometry Principles
Visibility Dimming Coefficient (abbreviated to Dim K or Vis K)
Fine particles suspended in the atmosphere will scatter a beam of light so that the intensity of the
beam reduces as it passes through the air. This reduction in visibility is directly proportional to the
concentration of suspended dust particles.
The intensity of a beam of light follows the Lambert Beer law:
I= Ioe -KL
where K is a parameter known as the visibility coefficient and is proportional to the concentration of
the suspended particles and L is the path length of the beam.
I/Iois the ratio of the measured beam intensity and that of the initial intensity Ioand is known as the
transmissivity (T) of the system:
T = e -KL
Thus visibility coefficient :
K = 1 . loge1
L T
where L = 6m & T is the measured transmissivity.
A visibility sensor measures the transmissivity of a light beam from a source of known brightness over
a fixed path length to enable a value of the visibility coefficient to be deduced. The units of
measurement for this coefficient are m-1 and the typical span range would be 0 - 0.015m-1 or 0 -
15(km)-1.
Visibility
An alternative method of presenting this data is in the form of meteorological visibility. This is defined
as the distance over which the intensity of transmitted light falls to 5% of its initial value. It represents
the distance over which a person can see in a hazy or dusty environment.
In this case, I= 0.05 x Io thus T = 0.05
and since K = 1 . loge1
L T
visibility L = 1 loge20 = 2.99
K K
Thus, for a K value of 0.003, the visibility in metres is 2.99/0.003 = 1000m.
Both K factor and visibility are calculated by the sensor and are available for output.

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2.1.1.2.
LED Control
Operation of the emitting LED is controlled by the on-board processor. The LED is pulsed periodically
as shown in figure 4.These very brief duration pulses enable the instrument to operate without
interference from other light sources within the tunnel.
Figure 4: LED Pulse Graph
2.1.1.3.
Measurement Elements
The visibility channel produces a modulated beam of light from a pulsed LED focused by a lens to a
retro-reflector mounted some 3m away. An internal detector monitors the brightness of the emitted
pulses of light (Vis Tx). The reflected beam is gathered by a second lens and focussed onto a
receiving detector (Vis Rx). The ratio of signals from the two detectors provides the measurement of
transmissivity.
2.1.1.4.
Detector Element
Two silicon detectors are utilised one to measure the initial brightness of the emitted light (Vis Tx), the
other to measure the intensity of the received light (Vis Rx) after transmission to and reflection from
the retro-reflector unit.
The processor takes a series of measurements immediately prior to 'pulsing' the emitter LED in order
to monitor the inherent background levels of light intensity. Then a series of measurements is made
while the LED is illuminated and again after the LED is switched to check that the background levels
haven’t changed. The high frequency at which this occurs provides the device with extremely high
immunity from the effects of background lighting.
2.1.1.5.
Calibration
It is normal for these instruments to be calibrated during a tunnel closure when it is expected that the
opacity will be zero. The instrument can be calibrated by selecting a calibrate mode where, instead of
calculating opacity using a fixed calibration factor, the instrument assumes an opacity value of zero
and calculates the calibration factor required.
Set Cal Vis = 1000000 x (Vis Tx/Vis Rx)
2.1.1.6.
Diagnostic Data
Measurements of opacity and transmissivity are calculated from the two detector measurements. First
the detector measurements are smoothed to improve signal to noise and calculations made as
follows:

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In order to calculate the opacity from the data collected by the detectors, a Y value has to be
established. This is done by using the Vis TX and Vis RX data, along with the Set Cal as shown in
section 2.1.1.5;
Y Value = 1000000- (Vis Rx/Vis Tx x Set Cal)
This Y Value is then used to establish the Opacity as a percentage as shown below;
Opacity = Y/10000
Opacity is a direct reading of the attenuation of light. Zero opacity equates to a totally clean light path
and 100% to total light attenuation.
This can then be used to calculate the transmissivity as a percentage and vis K as shown below;
Transmissivity = 100 –Opacity %
K = 1 . loge1
L T
2.1.1.7.
Auto Zero
The measurement of opacity is dependent upon the optical surfaces of the instrument remaining
clean. If the surfaces of the instrument lenses or the retro-reflector become contaminated it will
reduce the intensity of the received light and increase the opacity measured value. Over a period of
time, it is normal to observe a slow build-up of optical contamination resulting in a steady increase in
the measured opacity value. This appears as a persistent positive output drift.
There are two cures for this problem. One is to clean the optical surfaces on a regular basis.
However, in a road tunnel regular access is not usually possible without a tunnel closure.
The second method is to automatically compensate for such a build-up of contamination. The
technique used by Tunnel Tech relies on the assumption that there will always be periods of low real
opacity during the course of the day. These periods usually occur at night when traffic loading is low.
These periods provide a reference condition for the measurement.
During normal operation, the effect of contamination will be a slow increase the measured value of
opacity. To compensate for this the instrument is programmed to slowly reduce its measured value of
opacity at a rate faster than that at which contamination would increase.
In this way periods of zero opacity, whenever they occur, are utilised to correct the calibration of the
measurement allowing long periods of operation without maintenance and the cleaning of optical
lenses.
2.1.2.
Electro Chemical Cell –CO/NO/NO²
In order to measure the level of gas (CO/NO/NO²), the Tunnel Tech 700 uses an electro chemical cell
to convert the gas in to readable data. The gas diffuses in to the sensor and interacts with the
electrode within the cell. This causes a chemical reaction in which the gas is reduced or oxidised. The
electrochemical reaction results in an electric current which can then be read, with the generated
voltage being linear to the gas response, and the detector level is derived from the incoming voltage
and subsequently a gas measurement.

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3.
Specifications
3.1.
General
Construction
- corrosion resistant epoxy coated aluminium housings sealed to IP66 (AQM & PSU)
- optional 316 stainless steel and 316 stainless steel TI for heads and brackets
Electro-magnetic immunity
- shielded to comply with 73/23/EEC - low voltage and 89/336/EEC-EMC
Ambient temperature
- -20oC to +50oC
3.2.
Power Supply Unit (PSU) (Optional)
Outputs
- 24V DC fused
- maximum current output must not exceed 5A (60W)
Power
- 90 to 264V AC, 47/63Hz, 100VA max.
Dimensions
- 230mm x 200mm x 110mm
3.3.
Air Quality Monitor
Monitoring channels
- up to 4 channels for CO, NO, NO², and visibility
Measurement path
- 3m (6m folded beam)
Measuring range (standard)
- Visibility: 0-0.015 m-1
- CO: 0 - 300ppm
- NO: 0 - 30ppm
- NO²: 0 –5/10ppm
- Other ranges selectable on setup
Averaging time
- 1 to 12 minutes

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Accuracy
- Visibility - ±0.002 m-1
- CO - ±2ppm or 2% span
- NO - ±2ppm or 2% span
- NO² - ±100ppb
Power
- 24V DC, 24VA (obtained from PSU)
Communications
Serial RS485 interface via plug and socket for diagnostics, RS485 Modbus, or Codel
Protocol
Outputs
(Optional)
- analogue - 2 x 4-20mA, 200V Common
- max. load 500
-logic - 2 x volt-free contacts SPCO, 0.5A @ 125V AC,2A @ 30V DC, 0.5A @ 100V
DC (Per card, up to two cards per unit or system)
- Optional Modbus protocol serial communications (must be specified at the time of
order).

Dimensions
- Ø150mm x 260mm
3.4.
RS485 Interface (Optional)
Power
- 5V, 30mA obtained from AQM
PC Communications
- RS485 via 9-way ‘D’ connector
AQM Communication
- TTL levels
- connection via 4-way plug and socket
- isolated
Note: The AQM PCBs are equipped with built-in RS485 communications facilities for use during
commissioning. This facility may further be used after commissioning for communication to
integrate the AQM using MODBUS protocol –fuller details are contained in Appendix A.

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4.
Installation
Be sure to observe all necessary safety precautions at all times during installation.
All cable gland entry holes are drilled and tapped M20 x 1.5 and are fitted with blanking
plugs. Cable glands are to be supplied by the customer according to the cables used during
installation.
4.1.
Mounting Details
After unpacking the equipment check, using the packing list provided, that all items are present. The
Air Quality Monitor (AQM) is carried on a fabricated mounting bracket (if supplied
4.1.1.
Air Quality Monitor (AQM)
The AQM comprises a transceiver and reflector unit. Secure the AQM to the tunnel wall by the
mounting brackets supplied using 4 x M8 bolts (by others) such that the transceiver and reflector are
approximately 3m apart. The transceiver and reflector should be mounted horizontally and arranged
as illustrated in
Figure .
Figure 5 : AQM –mounting holes
4.1.2.
Power Supply Unit (PSU)
Mount the PSU to the tunnel wall again using 4 x M6 bolts (by others). Mounting hole details are
shown in the illustration Figure .
Clean air tubes are supplied and
should be bolted onto the
mounting brackets using the 3 x
M6 bolts provided.

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Figure 6 : PSU –arrangement
4.2.
Connections
Wiring should only be undertaken by a qualified technician.
The following electrical schematic illustrates the connections for the Tunnel Tech 700 Series system.