Turn Key iGAS User manual

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iGAS Operating Instructions, Issue 6, Apr 2018
TURNKEY ® iGAS® OPERATING INSTRUCTIONS
The following associated documentation is available from www.iGASES.uk
•iGAS Installation Instructions
•Installing the Power Portal
•Connecting iGAS to AirQWeb
BEFORE YOU START
iGAS® is supplied with its air filters removed. It is important these are refitted before you start to
use the instrument. Please refer to Figure 7 of the iGAS Installation Instructions. The larger Zero
Filter screws into the adaptor on the left, the twin o-rings of the smaller PTFE sample filter push
into the adaptor on the right. Before you begin, please make sure both filters are installed
correctly.
IMPORTANT: REMOVE THE END CAPS FROM A NEW ZERO FILTER AND IT ALLOW TO VENT FOR
24 HOURS BEFORE FITTING. OTHERWISE, WHEN A NEW ZERO FILTER IS FITTED, IT CAN TAKE
SEVERAL HOURS FOR THE READINGS TO STABILIZE, ESPECIALLY CO, H2S and SO2
It is recommended that the filters are changed at 3-monthly intervals, however, filter life may
vary depending on local ambient conditions. iGAS is supplied with one spare set of filters. It good
practice to mark the filters with their installation date.
A Filter Shield is provided with the instrument and this should be fitted when the instrument is
installed. It prevents the filters rapidly heating-up in direct sunshine and provides some
additional anti-tamper security. Please refer to the installation guide for more information.
iGAS is supplied in a weather proof case and, providing the Manifold temperature does not
exceed 45⁰C, will operate unshielded in most temperate climates. However, if the instrument is
to be installed in tropical locations, a full Sun Shield is available. This prevents the instrument
case overheating by reflecting away direct sunlight and is fitted in place of the standard Filter
Shield. Please contact Turnkey for more information

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iGAS Operating Instructions, Issue 6, Apr 2018
PREAMBLE
iGAS® operates automatically under the control of AirQWeb and associated programs and
Apps. The instrument is supplied pre-configured so that it will start operating automatically as
soon as it is connected to AirQWeb.
iGAS is factory set to measure the following
•Measurements are in SI units
•Reporting interval is 1 minute
•Viewing interval is 2 seconds
•Zero phase length is 1 minute
•Continuous zero correction is enabled
Visit www.iGASES.uk to download more information.
The rest of this document gives deeper knowledge of the instrument to allow the operator to
change its operating mode to suit their application. These changes can be made using AirQWeb
or other programs and Apps. All sampling measurements must be stopped before any of the
instrument’s settings can be changed.
Operation of the instrument is controlled by the state of its Feature Flags and its Instrument
Settings. Its operational state is indicated by the Instrument Information table, Fault Flag
states and Diagnostic & Housekeeping Readings.
Please see Appendix of this document for full lists of the Feature Flags, Instrument Settings,
Fault Flags and Diagnostic readings.
The electrochemical cells used in iGAS need to be held under a constant bias voltage even when
the instrument is not being used. With 8 cells connected, this draws a current of about 10 mA
from the battery, WHICH MEANS THE BATTERY WILL BECOME EXHAUSTED AFTER ABOUT 10
DAYS.
If you intend not to use the iGAS instrument for several days, disconnect the battery by setting
the power isolator switch to O. Return the switch to 1 when you wish to start using the
instrument again. Note that the electrochemical cells may take several hours to recover after
powering down. Wait until their readings stabilize. You may also momentarily click the isolator
switch if, for whatever reason, you need to reboot the instrument.
AIR QUALITY INDEX
The Air Quality Index (AQI) is based on the concentration of various gaseous and particulate
pollutants. Current values for the UK and USA are listed in the following tables: but be aware, the
UK index runs from 0 to 10, the USA one 0 to 500!

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iGAS Operating Instructions, Issue 6, Apr 2018
EU and UK DEFRA
The Daily Air Quality Index (DAQI) in the leftmost column tells you about levels of air pollution
and provides recommended actions and health advice. The index is numbered 1-10 and divided
into four bands, low (1) to very high (10), to provide detail about air pollution levels in a simple
way, similar to the sun index or pollen index.
USA EPA
The carbon monoxide (CO) readings are in ppm (parts per million). The UK readings are given in
µg/m3, the USA EPA in ppb (parts per billion). The conversion between the two is given by the
following table, iGAS can record results either in ppb or µg/m3 (see Feature Flags)
1 ppb
µg/m3
SO2
2.62
NO2
1.88
NO
1.25
O3
2.0
CO
1.15
H2S
1.47
VOC
2.29
CO2
1.80

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iGAS Operating Instructions, Issue 6, Apr 2018
ZERO GAS AND SAMPLE FILTERS
iGAS is fitted with a pair of air filters, one of which is used to generate a zero gas. The air
sample is selectively drawn through these filters by a pair of ultra-quiet pumps. The humidity
and temperature in both air sample streams is equalized using Nafion drier tubes. Looking at
the instrument door, the larger Zero Filter is on the left, the Sample Filter on the right.
The Zero Filter uses a standard AXP3 respirator filter with Rd40 thread.
For iGAS we specify AXP3 Rd40 respirator cartridges. These contain a P3 particle filter and AX
micro-porous activated coconut charcoal only. They contain no impregnated charcoal. There is
some evidence that metal impregnated charcoal may increase the catalytic reduction of water
vapour to H2and CO by the charcoal.
All charcoal filters will catalytically reduce water vapour to create ppb levels of hydrogen and
carbon monoxide. The activity increases with increasing temperature and the Filter Shield
protects the Zero Filter from sudden temperature changes. Since hydrogen can have a
significant effect on electrochemical cells, especially SO2 and H2S, iGAS incorporates special
sensors to compensate for the effect.
The Sample Filter is a 1 micron PTFE membrane filter which is used simply to prevent ambient
dust particles being drawn into the instrument when sampling. A PTFE membrane is used to
minimize absorption of sample gases, especially ozone. Note that most P3 respirator filters
absorb ozone and acidic gases, especially SO2, and are not suitable.
The AXP3 Zero Filter contains about 300g of pure activated charcoal which absorbs most
polluting gas species. Note that this Zero Filter will not absorb carbon monoxide and iGAS is
factory configured to exclude CO from the zero correction scheme. This is feasible because the
CO sensor is stable at ppm levels of pollution and, therefore, does not need zero correction.
It is recommended that the filters are changed at 3 monthly intervals but the actual lifetime of
the Zero Filter will depend on the level of ambient pollution, humidity, and the zeroing scheme
used. The Continuous Zeroing scheme (see below) uses the Zero Filter most and draws about 10
litres of air per hour through it. Filter breakthrough is unlikely to occur before 1 gram of
pollutant gas has been absorbed, equivalent to about 106ppm litres of flow if 1ppb=1µg/m3.
This corresponds to < 1% of the weight of the activated charcoal.

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iGAS Operating Instructions, Issue 6, Apr 2018
ZEROING SCHEMES
There are three zeroing schemes which may be selected to compensate for temperature and
humidity drift in the sensors. Use the Feature Flags to set the zeroing scheme you require. The
Continuous Zero is the factory default. Any of the sensors in the Manifold may be excluded
from the zeroing process by setting the SEDs accordingly.
Continuous Zeroing: Air is alternatively drawn through the Zero Filter and then the Sample
Filter, the actual reading is the difference between the two measurements. The length of the
Zero Phase determines how long the air is drawn through each filter and measurements are
taken for 10 seconds at the end of each phase. The shortest (default) phase time is 1 minute,
meaning the air is alternatively drawn through the Zero Filter for 1 minute and then through
the Sample Filter for 1 minute. If Use Rise Time is selected, the 90% response time (T90) of the
cell is taken into account when the results are calculated.
Continuous Zeroing overrides all other zeroing schemes and is the recommended mode of
operation. Use to acclimatize a new Zero Filter.
Periodic Zeroing: Measures the sensor offsets at the Zeroing Interval specified in the
Instrument Settings. If the Zeroing Interval is zero, the offsets are just measured at the start of
the sample. Each offset measurement takes three Zero Phases, make sure you select the
feature Use Periodic Zeros to actually apply those offsets. The advantage of this method is the
zeroing takes place only infrequently allowing a faster reporting interval to be used. It also
maximizes the lifetime of the Zero Filter but may give rise to more offset drift between
successive zeros. However, unless there are significant changes in temperature or humidity, this
will be small on the AQI scale.
Temperature Zeroing: If neither of the above Feature Flags are set, the instrument will measure
the sensor offsets whenever the Manifold Temperature has changed by the amount specified
by the Zero Trigger temperature specified in the Instrument Settings. Again, select Use Periodic
Zeros to apply the measured offsets.
In all cases the default zero phase length is 1 minute.

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iGAS Operating Instructions, Issue 6, Apr 2018
SAMPLING
Sampling is the process by which the instrument measures and stores readings from its gas
specific sensors. Each sample consists of a series reports measured over successive time
intervals, this is the Reporting Interval. The series of reports which make up the sample is
known as the time series. The reported readings will be the average (or sometimes the peak)
value over the reporting interval. Average (or peak) readings are also recorded over the
duration of the sample.
Sampling may be started and stopped automatically as defined by the Feature Flags. Automatic
samples are generally aligned with 1 minute boundaries.
The shortest reporting interval is one second, the longest 50 minutes. The recommended
reporting intervals are between 1 minute and 15 minutes, these give the best compromise
between memory use and time resolution. The shortest sampling period is one report interval,
the maximum many days.
For those instruments with a display output, analogue output or micro-website, the Viewing
Interval specifies how often the output is updated. The output is the average (or peak) over the
specified viewing interval. The viewing interval can be in the range 1 second to 30 minutes and
is independent of the reporting interval.
The instrument’s memory can hold up to 100 samples each consisting of many reports. A
sample is identified by its Sample Number. When the memory is cleared the sample number is
reset. The total number of samples measured by the instrument over its life is the Sample
Total.
SAMPLE CONTROL FEATURE FLAGS
If Automatic Start is set, sampling will automatically start on the next 1 minute boundary after
the instrument is switched on. If Timed Sample is set the sample will last for the Duration
number of reports (specified in the Instrument Settings) and, if Automatic Start is set too,
another sample of the same duration will start immediately. This process will carry on till the
memory fills when a Memory Full Fault Flag will end the current sample and prevent another
restarting.
If Circular Buffer is set, the last sample (i.e. the one just finished) will be overwritten if the
Instrument Settings Sample Stack value equals 0, if it equals 1 the last but 1 will be overwritten
and so on. Hence it is possible to create a stack of N samples that will overwrite forever.
If New Sample Daily is set a new sample will start at precisely midnight but only if Automatic
Start is set. This can be combined with the Circular Buffer flag and the value of the Sample
Stack to create a rotating, N-day, sample block.

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iGAS Operating Instructions, Issue 6, Apr 2018
POWER MANAGEMENT AND SLEEPING
The instrument is fitted with a 6 Volt, 5 cell NiMH battery.
If the battery voltage drops below 5.5 Volts, measurements will stop and the current sample
will be terminated and the Dead battery Fault Flag will be set. If the battery drops below 5.2
Volts the instrument will go into a low power sleep to conserve energy (regardless of the state
of the AllowToSleep flag). The Dead Battery flag will only be cleared when the battery voltage
has recovered to > 5.8 Volt
The Low Battery Fault Flag is set when the battery voltage drops below 5.8 Volt. An existing
sample will continue but a new sample cannot start while that flag is set.
When the instrument is on-charge the red light is always on.
The iGAS internal battery capacity is 2000 mAH. The battery is intended to keep the instrument
operating if the external +12 Volt power disappears. Assuming a full charge, iGAS will continue
to operate without external power for about 10 hours.
If the battery is discharged, a full recharge will take about 12 to 14 hours with the instrument
automatically switching on before then when the battery reaches 6.5 Volt.
The battery is not required for data storage and the instrument uses flash memory to store the
results. Data retention is more than 100 years.
When you have finished using the instrument, it is good practice to clear the Automatic Start
flag, stop the instrument sampling, and set the Allow To Sleep flag. This will allow the
instrument to sleep until next required while only slowly discharging its battery. You can do
this by clicking Hibernate in AirQWeb. Remember, if you wish to turn off for several days, you
must isolate the battery by clicking the isolator switch to 0

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iGAS Operating Instructions, Issue 6, Apr 2018
GETTING STARTED WITH iGAS®
Please refer to the latest versions of the associated documentation for instructions on how to
install iGAS, the Power Portal, and connect to AirQWeb. All the latest documentation can be
found at www.iGASES.uk .
To turn the instrument on, switch the toggle switch to 1. The instrument will only start if the
battery voltage is greater than 5.8 Volts. If it isn’t you must connect the +12 Volt power supply
from the Power Portal and wait until the battery is sufficiently charged. The red light will appear
when external 12Volt power is connected.
If a 12 Volt power supply is connected, the instrument will automatically turn-on if the supply
voltage is > 9 Volts and the battery voltage is > 6.5Volts.
The instrument can also be turned on remotely by sending a 1 second RS485 BREAK command
from the WS3 web server in the Power Portal. Please refer to your AirQWeb documentation.
If the Allow to Sleep Feature Flag is set and
1. there is no communications activity
2. the instrument is not measuring a sample
the instrument will automatically fall asleep after about 5 minutes. The instrument can be
awoken again by toggling to power switch, sending a BREAK command or simply connecting the
+12 Volt supply. The instrument will not fall asleep if the +12 Volt supply is connected and the
battery voltage is > 6.5 Volt.
Applying mains power to the Power Portal should automatically establish an internet
connection between iGAS and AirQWeb. Please refer to Connecting iGAS to AirQWeb from
www.iGASES.uk for more instructions.
Please contact [email protected] if you experience any difficulties.

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iGAS Operating Instructions, Issue 6, Apr 2018
APPENDIX
FEATURE FLAGS
(shown as underlined italics in the text)
The operation of iGAS is controlled by Feature Flags which may be set or cleared by the operator. They
are normally set automatically by AirQWeb. The basic set of Feature Flags is as follows, preset factory
defaults are shown ticked:
Feature Flag Name
Explanation/Description
iGAS
√
Measure gas concentrations
iEXTRA
√
Measure extras such as NOX, ambient CO2, manifold T,
sample T
iDUST
Measure particle concentrations, iDUST module required
iMET
Measure meteorological conditions, iMET module required
US units
SI units by default
IGAS mass/volume
Express gas concentrations as µg/m^3 instead of ppb
Auto Start
Automatically start sampling whenever power is on and
battery condition is OK
Daily sample
New sample starts at midnight each day, the Auto Start
feature must be on. Will terminate active sample at
midnight.
Timed sample
Each sampling period terminates after a set number of
reports, specified in the Instrument Settings table (IS)
Stop if fault
√
Stops sampling if a fatal fault occurs
Continuous Zero
√
Continually determine sensor zero gas offset. Overrides
Periodic Zero flag. Takes two Zero phases to complete (2
minutes by default).
Periodic Zero
Measure sensor zero gas offset at start of sampling and
thence at the Zeroing interval specified in the instrument
Settings. Takes three Zero phases to complete
Use Period Zero
Apply the zero offset readings determined by the Periodic
Zero above. Over-ridden by the Continuous Zero Flag
Apply offsets
√
Apply the systemic zero offsets, manually entered into SEDs
Use rise times
√
Correct for T90 response time
iDUST Auto Zero
Only If the iDUST module is fitted, measures the zero dust
particle count.
Continuous PID lamp
Power the PID lamp continuously
Circular Buffer
Use circular buffers to record stacked samples, number of
stacked samples saved before overwrite is specified in the
Instrument Settings Table (IS)
Calculate NOX
Calculate NOX=NO2+NO. Sensors must be fitted
Swap Air Filters
Electronically interchanges the chemical air filters, so the
sample filter becomes the zero gas filter and vice-versa
Use iGAS Matrix
√
Correct for gas species interferences. Gas matrix elements
must be defined in SEDs
Age correction
Apply the sensor cell ageing characteristic from SEDs.
Typically -2% per month
Disable CCC
Turn off Carbon Catalysis Compensation measurement
No CCC
Don’t apply Carbon Catalysis Compensation

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iGAS Operating Instructions, Issue 6, Apr 2018
Save iGAS
√
Save the iGAS readings in the dataset
Save iEXTRA
√
Save iEXTRA readings in the dataset
Save iDUST
Save the iDUST readings in the dataset
Save iMET
Save the iMET readings in the dataset
Save housekeep.
Save the Housekeeping readings in the dataset
Save diagnostic
Save the Diagnostic readings in the dataset
Save GPS
Save the GPS co-ordinates if GPS module is fitted
Allow to sleep
√
Allow to fall asleep after about 5 minutes if not sampling
and no communications. Toggle switch or send break to
command from WS3 to awaken. Will automatically awaken
and not fall asleep if +12V connected and battery > 6.5V
Dummy readings
For test purposes only
Calibrate iGAS
Use default 1000nA/ppm sensitivity
Calibrate iDUST
Apply calibration to iDUST module
Use time server
Use internet time server to set time, requires WiFi module
Use WiFI
Use WiFi, requires WiFi module
Measure manifold pressure
Measure manifold flow pressure
Sample T&RH
Sample temperature and humidity sensor is fitted
Power photoionization detector
Supply power to PID, sensor must be fitted
Lamp can be operated intermittently to save power
Measure atmospheric pressure
Sensor is fitted by default. Measures enclosure T too
Measure ambient T & RH
External T & RH sensor must be fitted
Measure ambient CO2
Measure ambient CO2, sensor must be fitted
Measure iDUST sample flow
Measure iDUST sample flow, sensor must be fitted
Measure wind speed & direction
Requires iMET with anemometer module
Measure insolation
Requires iMET with solar module fitted, measures intensity
of sunlight in W/m2
Measure rainfall
Requires iMET with tipping bucket rain gauge.
INSTRUMENT INFORMATION
(show in bold font in the text)
The Instrument Information table (II) provides additional information about the instrument. It is read
only and cannot be modified by the user. Some of the values (SEDs) are automatically uploaded from
the Manifold. Not all of the Instrument Information is listed below.
Information Table (II)
Explanation/Description
Serial Number
Instrument serial number
Instrument type
iGAS Monitor
Manufacturer
Turnkey UK
Software Version
Software version programmed into instrument
Gas Manifold
iGAS Manifold serial number
Cal. Due by
Date next instrument re-calibration is due.
CH0 to CH7 names
Names of the primary measurements
CH0 to CH7 units
Measurement units for the primary measurements
Gas-A to Gas-H cal. dates
Calibration dates of the individual gas sensors
Gas-A to Gas-H type
Species and type of the individual gas sensors. For
example, NO-B4 is a 4 -electrode electrochemical
nitric oxide sensor

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iGAS Operating Instructions, Issue 6, Apr 2018
Gas-A to H GasCode & SN
The two character GasCode and serial number of the
individual gas sensors
Gas-A to H elect. offset
Intrinsic zero electrical offset of the gas sensors
Gas-A to H syst. offset
The systemic zero offset determined for the manifold
Gas-A to H signal/ppm
The sensitivity of the gas sensors, typically in nA/ppm
for electrochemical cells
Gas-A to H periodic zero
The cell zero offset as determined by the latest
periodic zero.
Gas A to H CC Comp %
The Carbon Catalysis Compensation in %
Gas A to H vol. to mass
The volume to mass conversion factor of each gas
species used to convert, for example, ppb to µg/m3
Gas-A to H ageing %/month
The sensitivity ageing characteristic for the individual
gas sensors in % per month, negative values means
sensitivity is lost
Gas-A to H 90% rise time
The 90% response time (in seconds) to a step
function change in gas concentration, aka T90
INSTRUMENT SETTINGS
(show in bold font in the text)
These settings control the instrument’s reporting and sampling. They are normally controlled
automatically by AirQWeb. Not all of the Instrument Settings are listed below.
Instrument Setting
Explanation/Description
Sample Total
Running count of total number of samples taken by the
instrument over its life. Never normally reset.
Sample Number
Next sample number, is reset to 0 when memory is
cleared. Increments by 1 every time a sample is
completed. Range is 0 to 99. Sample 0 is always the first
sample.
Reporting interval (sec)
Time interval when new results are reported.
AirQWeb normally sets this to 5 minutes (300 secs)
Flow (scc/min)
The set point sample flow for iDUST
Zeroing (sec)
The interval in seconds between iGAS and iDUST periodic
zeros, if 0 will just do zero at start of sampling
Viewing (sec)
The display refresh rate for those instruments with a
display or micro website
Start time
If sampling, start timestamp of current sample. If not,
start timestamp of last sample
Stop time
If sampling, timestamp of latest report. If not, stop
timestamp of last sample

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iGAS Operating Instructions, Issue 6, Apr 2018
Sample Stack
Number of samples in the stack before loopback if
Circular Buffer Feature Flag is selected
Zero phase (min)
The length, in minutess, of each iGAS zero phase, either
continuous of periodic.
Zero trigger dT
The temperature change dT in ⁰C of the gas sensor
manifold since the last periodic zero to trigger another.
Report Number
Number of reports in the current sample, or last sample if
not sampling.
Duration (rpt)
Number of reports in a sample before it auto-stops, only
if Timed Sample Feature Flag is selected. If AutoStart is
set, will restart a new sample. If Circular Buffer is set will
accumulate a circular buffer of samples. Sample Stack
sets the number of contiguous samples in the buffer.
Company
Company name string, up to 16 bytes
Location
Location name string up to 16 bytes
Gas Sensor Mask
Mask showing which sensors are fitted in the iGAS
manifold
Zeroable Mask
Mask showing which of those sensors are suitable for
continuous or periodic zeroing
Manifold hours
Hours the gas sensor manifold has been used.
Diffometer
iGAS filter (h)
iDUST filter (mg)
Last AZ Temp.
Temperature of manifold during last periodic zero
Last AZ humidity
Humidity of sample gas flow during last periodic zero,
only if sample flow T &RH sensor fitted
Last AZ at
Time and date of last none-continuous autozero
Manifold at
Time and date iGAS Manifold fitted
Diffometer at
Time and date iDUST Diffractometer fitted
iGAS filter at
Time and date iGAS filters change
iDUST filter at
Time and date iDUST filter changed

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iGAS Operating Instructions, Issue 6, Apr 2018
FAULT FLAGS
(shown as underlined italics in the text)
These flags indicate the faults or errors the instrument has encountered. Many of these are managed
automatically by AirQWeb.
FAULT FLAG
Explanation/Description
Directory FULL
100 samples have been stored. Sampling is stopped and
canniot restart. Upload and clear memory
Memory FULL
The IvIbe memory is full. Sampling has stopped. Upload
and clear memory. Depending on length of samples, may
occur before 100 samples have been saved.
Dead battery
Battery voltage < 5.5Volts. Sampling will have been
stopped and cannot re-start until battery voltage . 5.8
Volts.
I’m too hot!
The case temperature is >60C. Sampling is stopped
Fatal Error
One of the above faults has occurred, sampling is stopped
until fault condition clears.
Memory 90% full
Memory is at 90 % capacity, stop sampling and clear
memory.
Low battery
The battery voltage is < 5.8 Volts. Recharge battery. New
sample cannot be started.
Cal. < 50 day
Calibration is due in less than 50 days. Have instrument
recalibrated.
Cal. OVERDUE
Calibration is now overdue. Soon the instrument will be
disconnected from AirQWeb server. Have instrument
recalibrated as soon as possible..
PID warning
The PID lamp has failed or needs cleaning

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iGAS Operating Instructions, Issue 6, Apr 2018
NOTES
Please visit www.iGASES.uk to access other iGAS and iDUST documentation
If you need assistance, please contact:
Turnkey Instruments Ltd, Dalby Court, Gadbrook Business Centre, Northwich, England CW9 7TN
Tel: [phone] Fax: [phone]
Email: [e-mail]
Revision History
•Original, 7 May 2017
•18 April 2017, issue 6, for iGAS HashCode 64, G1.90mjl
© 2017 Turnkey, MJL, Issue 6, Apr 2018
CE 2017
www.turnkey.tel
Turnkey®, iGAS ® and iDUST® are registered trademarks