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Instrument User Manual V1.0
GASCLAM 2
GasClam 2 Instrument User Manual
Ion Science Ltd.
Unrivalled Gas Detection. ionscience.com
2
Thank you for purchasing your Ion Science instrument.
Register your instrument online for the warranty
The standard warranty of your GasClam 2 is for one year.
To receive the warranty, you must register your instrument online within one month of
purchase (terms and conditions apply).
Visit ionscience.com/instrument-registration
Part number: 873203
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Contents ________________________________________________________________________
Declaration of conformity 4
Statements 5
Validity of this Manual ..................................................................................................................................................... 5
Responsibility for Correct Use .......................................................................................................................................... 5
Warnings .......................................................................................................................................................................... 5
Quality Assurance ............................................................................................................................................................. 5
Disposal ............................................................................................................................................................................ 5
Legal Notice ...................................................................................................................................................................... 5
Warranty .......................................................................................................................................................................... 5
Service .............................................................................................................................................................................. 5
Contact details.................................................................................................................................................................. 6
Introduction to GasClam 2 7
Package Contents ............................................................................................................................................................. 8
Parts Description .............................................................................................................................................................. 8
How the GasClam 2 Works ............................................................................................................................................... 9
User Accessible Parts........................................................................................................................................................ 9
Planning Monitoring and Site Preparation 9
Number of Units and Site Layout ................................................................................................................................... 10
Hazardous Areas............................................................................................................................................................. 10
Borehole Headworks ...................................................................................................................................................... 10
GasClam 2 Configuration and Setup 11
Software ......................................................................................................................................................................... 11
Power Supply Options .................................................................................................................................................... 11
External Power Supply ................................................................................................................................................... 12
Remote Data Acquisition................................................................................................................................................ 12
Battery Life and Sample Count....................................................................................................................................... 12
The Effects of Temperature and Humidity on Sample Count ........................................................................................ 13
Temperatures Below 0°C................................................................................................................................................ 14
The Effects of Water on a GasClam 2 ............................................................................................................................. 14
How the GasClam 2 Prevents Water Entering From Below ........................................................................................... 14
How the GasClam 2 Prevents Water Entering From Above........................................................................................... 15
Optimising GasClam 2 Performance .............................................................................................................................. 15
Start Monitoring 15
Changing Batteries ......................................................................................................................................................... 15
Connecting the GasClam 2 to a PC ................................................................................................................................. 17
Check Voltages and Settings .......................................................................................................................................... 17
Installing the GasClam 2 in a Borehole.......................................................................................................................... 17
Turning the GasClam 2 On ............................................................................................................................................. 18
Leaving the Site .............................................................................................................................................................. 18
Site Visits 18
Regular Checks ............................................................................................................................................................... 19
Data Retrieval ................................................................................................................................................................. 19
Leaving the Site .............................................................................................................................................................. 19
Calibration, Servicing and Storage 19
Unit Calibration and Service ........................................................................................................................................... 19
Storing the GasCalm when Not In Use ........................................................................................................................... 20
Filter Management ......................................................................................................................................................... 20
Inspecting and Replacing the Moisture Filter ................................................................................................................ 20
User Serviceable Parts .................................................................................................................................................... 21
User Spare Parts ............................................................................................................................................................. 22
Fault Finding 23
Software ......................................................................................................................................................................... 23
The Effects of Flooding on Data and the GasClam 2 ...................................................................................................... 23
Potential Problems when GasClam 2 used Below 0°C ................................................................................................... 23
Technical Specification 24
General Specification ..................................................................................................................................................... 24
Dimensions ..................................................................................................................................................................... 25
Built-in Sensors ............................................................................................................................................................... 25
Gas Sensor Specifications ............................................................................................................................................... 25
GasClam 2 Instrument User Manual
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Unrivalled Gas Detection. ionscience.com
2
Cross sensitivities and Sensor Performance: ................................................................................................................. 26
GasClam 2 Instrument User Manual
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Unrivalled Gas Detection. ionscience.com
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Symbols ________________________________________________________________________
WARNING!
USED TO INDICATE DANGER WARNINGS WHERE THERE IS A RISK OF INJURY OR
DEATH.
WARNING! - DANGER OF ELECTRIC SHOCK
USED TO INDICATE DANGER WARNINGS WHERE THERE IS A RISK OF INJURY OR DEATH
FROM ELECTRIC SHOCK.
CAUTION
USED TO INDICATE A CAUTION WHERE THERE IS A RISK OF DAMAGE TO EQUIPMENT.
PROHIBITED ACTION
USED TO INDICATE ACTIONS THAT ARE NOT PERMITTED; E.G. 'YOU MUST NEVER'.
INFORMATION
IMPORTANT INFORMATION OR USEFUL HINTS ABOUT USAGE.
Recycling and Disposal ____________________________________________________________
RECYCLING
RECYCLE ALL PACKAGING.
WEEE REGULATIONS
ENSURE THAT WASTE ELECTRICAL EQUIPMENT IS DISPOSED OF CORRECTLY.
GasClam 2 Instrument User Manual
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Declaration of conformity __________________________________________________________
GasClam 2 Instrument User Manual
Ion Science Ltd.
Unrivalled Gas Detection. ionscience.com
5
Statements______________________________________________________________________
Validity of this Manual
This User Manual gives information and procedures for the firmware version shown on the front page of this manual.
If you have different versions of firmware, please obtain the correct User Manual.
Responsibility for Correct Use
Ion Science Ltd accepts no responsibility for incorrect adjustments that cause harm or damage to persons or property.
The users are responsible to respond appropriately to the readings and alarms given by GasClam 2.
Use the equipment in accordance with this manual, and in compliance with local safety standards.
Reduced performance of gas detection might not be obvious, so equipment must be inspected and maintained
regularly. Ion Science recommends:
• you use a schedule of regular checks to ensure it performs within calibration limits, and that
• you keep a record of calibration check data.
Warnings
1. Read and understand this Manual fully before you install or operate the GasClam 2.
2. For safety, the GasClam 2 must only be operated by qualified personnel.
3. Substitution of components can result in unsafe conditions and will invalidate the warranty.
4. Surface mount fuses must only be replaced by Ion Science service centres.
Quality Assurance
The GasClam 2 is manufactured in compliance with ISO9001:2008. That ensures that the equipment is:
• designed and assembled reproducibly, from traceable components,
• calibrated to the stated standards before it leaves our factory.
Disposal
Dispose of GasClam 2 and its components in accordance with all local and national safety and environmental
requirements. This includes the European WEEE (Waste Electrical and Electronic Equipment) directive. Ion Science Ltd
offers a take-back service. Please contact us for more information.
Legal Notice
Whilst every attempt is made to ensure the accuracy of the information contained in this manual, Ion Science accepts
no liability for errors or omissions, or any consequences deriving from the use of information contained herein. It is
provided "as is" and without any representation, term, condition or warranty of any kind, either expressed or implied.
To the extent permitted by law, Ion Science shall not be liable to any person or entity for any loss or damage which
may arise from the use of this manual. We reserve the right at any time and without any notice to remove, amend or
vary any of the content which appears herein.
Warranty
To receive your 2 Year Warranty, you must register within one month of purchase (Terms and Conditions apply). You
will then receive a confirmation email that your Warranty Period has been activated and processed.
Full details, along with a copy of our Warranty Statement can be found by visiting: http://ionscience.com/customer-
support/instrument-registration
Service
Ion Science recommends a twelve-month service replacement of the MiniPID sensor lamp.
Contact Ion Science or your local distributor for service options in your area.
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Contact details
UK Head Office
Ion Science Ltd
The Hive, Butts Lane,
Fowlmere,
Cambridge,
SG8 7SL
UNITED KINGDOM
Tel: +44 (0)1763 208503
Fax: +44 (0) 1763 208814
Email: info@ionscience.com
Web: ionscience.com
USA Office
Ion Science Inc
4153 Bluebonnet Drive
Stafford
TX 77477
USA
Tel: +1 (877) 864 7710
Email: info@ionscienceusa.com
Web: ionscienceusa.com
German Office
Ion Science Messtechnik GMBH
Laubach 30
Metmann-Neandertal
40822
GERMANY
Tel: +49 2104 14480
Fax: +49 2104 144825
Email: info@ism-d.de
Web: ism-d.de
Italian Office
Ion Science Italia
Via Emilia 51/c
40011 Anzola Emilia
Bologna
ITALY
Tel: +39 051 0561850
Fax: +39 051 0561851
Email: info@ionscience.it
Web: ionscience.it
French Office
Ion Science France
41 Rue des Etoiles
83240 Cavalaire-Sur-Mer
FRANCE
Tel: +33 613 505 535
Email: info@ionscience.fr
China Office
Ion Science China Ltd
1101, Builiding B
Far East International Plaza
No. 317 Xiaxia Road
Shanghai
CHINA
Tel: +86 21 52545988
Fax: +86 21 52545986
Email: info@ionscience.cn
Web: ionscience.cn
GasClam 2 Instrument User Manual
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Unrivalled Gas Detection. ionscience.com
7
Introduction to GasClam 2 _________________________________________________________
GasClam 2 is the world’s first in-situ continuous borehole gas monitor and logging instrument. It is an invaluable
tool for detecting and recording the concentration of a wide range of gases commonly required in monitoring
applications, including Methane (CH4), Carbon Dioxide (CO2), Oxygen (O2), Carbon Monoxide (CO), Hydrogen
Sulphide (H2S) and Volatile Organic Compounds (VOC).
In addition to the selected gases, the GasClam 2 also records temperature, barometric pressure and borehole
pressure. An optional borehole water level sensor can be fitted to measure fluctuations in the water table should
this data be required.
Samples can be taken at programmable intervals, providing an invaluable set of data. The GasClam 2’s default
setting is to take a sample every hour, giving it an operational life of approximately one month (using the
rechargeable battery packs supplied) which can be extended up to 3 months (using optional proprietary long-life
Lithium battery packs).
The GasClam 2 can operate as either a stand-alone logger or real-time monitor linked to data acquisition systems
(Telemetry) via an optional modem system or communication cable. Recorded data can be viewed using the
GasClam 2 software or exported for analysis to a spreadsheet.
The software is also used to setup the GasClam 2 for logging, including logging intervals, total number of samples,
power supply and venting options.
The GasClam 2 itself is built to the highest standards with the outer casing from stainless steel, is intrinsically safe
and is certified for use in explosive environments in hazardous zone 1 and conforms to International Protection
code IP68.
Ion Science Ltd recommends that users perform regular bump tests in conjunction with an annual service and
calibration, which is provided by the Ion Science service department or an Ion Science approved service centre.
In this manual a Warning identifies conditions and actions that pose a hazard to the User or the Unit.
WARNING: Before using the GasClam 2ou must read this and the software manual paying particular attention
to the sections covering optimisation of GasClam 2 performance and the effects of water.
WARNING: Do not connect or disconnect any cables in hazardous areas and do not use non-approved
equipment in hazardous areas such as laptops, notebooks and mobile phones.
WARNING: For reasons of intrinsic safety, batteries MUST NOT be changed within hazardous areas. Always
ensure you are in a safe area before carrying out any type of work on your GasClam 2.
WARNING: To maintain the Unit’s certification and intrinsic safety use ONLY GasClam 2 approved batteries,
external power supply junction boxes and spare parts.
GasClam 2 Instrument User Manual
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Package Contents
When first unpacking take a little time to check and examine the contents of the GasClam 2 package:
• GasClam 2
• Power option (standard Charger, Power Supply and 2x Ni-MH rechargeable battery packs)
• Instrument Case
• Serial Communication Cable
• Push-Button Cable
• Allen key (no.5) for battery cover
• Box spanner for Barbs
• Allen key (no.4) for Vent Plug
• Vent Plug Set
• Spare Moisture Filters 2x
• Snorkel Set
• Spare Snorkel Filter
• CD Manual & Software, Calibration Certificate and Warranty
The GasClam 2 is packed for transport with caps on the inlet, outlet and vent barbs, these black caps must be
removed before the Unit is used. If it is intended to store the Unit for a longer period of time it is recommended to
replace the caps on the barbs to stop moisture and dust ingression.
Parts Description
GasClam 2 Head GasClam 2 Base
Identification Plates
Battery Cover
Plate
Communication
Port
Above-ground
Vent Barb
Port
Cap & Lanyard
Gas Inlet Barb
Gas Outlet Barb
Water Level
Sensor Port
Cap + Lanyard
Rubber Collar
Moisture Filter
Foldable Lifting
Handle
Water Proximity
(flooding) Sensor
Sensor Hook
Intrinsically Safe
Connection
Specifications
Version Number
Approval
Serial Number
Values are defined for
certification purposes
only. See
“Specification” for
operating values.
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How the GasClam 2 Works
When logging is started the GasClam 2 instantly takes its first sample. A click is heard and then the pump starts
which takes a sample of air from the borehole. First the pressure and temperature readings are taken. While the
pump is on readings from gas flow sensors are taken. The pump then switches off and after a short pause readings
from static gas sensors are taken. The whole process takes approximately 2 ½ minutes depending on sensor
configuration.
A set of readings is created and stored in non-volatile memory, the number of readings varies with the number of
sensors used. This set of readings is one “Sample”. The next sample can be taken after about ½ minute, hence the
minimum interval between samples which is the “logging interval” is 3 minutes.
The sampled gas is returned back into the borehole, however if required, a venting system can open a pathway
from the borehole to the atmosphere at specified intervals and for specified durations.
User Accessible Parts
WARNING: To ensure the GasClam’s intrinsic safety DO NOT dismantle or attempt any unauthorised servicing.
The GasClam 2 has only two main User
changeable parts: the Moisture Filter
which is accessed by unscrewing the
black Filter Cover tube (see section
“Servicing”) and the batteries which are
accessed by removing the Battery Cover
Plate (see section “Changing Batteries”).
Planning Monitoring and Site Preparation
Gas Inlet and
Battery
Communication
Moisture
Sensor
Vent
Barb
Main Gas Route
Above-ground Venting Option
Battery Packs
Battery Cover Plate
Moisture
Filter Cover
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Number of Units and Site Layout
To achieve the required effectiveness of site monitoring the types of
gases (see section “Specification”) and additional parameters including
water level that need be monitored should be defined and the GasClam
2 units need to be configured and calibrated accordingly prior to
deployment in the field.
Also the number of GasClam 2 units to be used and the location of the
boreholes should be planned with consideration to access, ground water
and possible flooding.
Hazardous Areas
It is important to define the extent of hazardous areas in accordance with national and local standards and how
far these areas extend away from the boreholes where GasClam 2 will be deployed.
Borehole Headworks
The GasClam 2 is designed to fit in a 50 mm (2”) borehole. The recommended Headworks are 8” Monitoring wells
from Stuart Wells (http://wellservices.stuartgroup.ltd.uk/) or a similar type and should be installed following the
diagram below:
It is important to have the standpipe a maximum of 3 cm above the base of the Headworks, this will ensure the
GasClam 2 will fit under the lid of the cover. The Headworks must be concentric to the standpipe for the GasClam
2 to be housed correctly. The standpipe must also be cut square to allow a good seal.
If a protective cover is to be used make sure this ends below the top of the standpipe otherwise the GasClam 2will
not fit correctly.
Concrete Collar
GasClam 2
Gravel
Max clearance 3 cm
Standpipe
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GasClam 2 Configuration and Setup
Software
Installation
The GasClam 2 software will run on: Windows XP SP 2, Windows 7, Windows 8.0 and 8.1.
The GasClam 2 software is on the CD (latest version can be provided by your service centre), it includes an
installation package with .Net Framework 4 (x86) (downloadable also from the Microsoft website) and a PDF
manual. The software needs 45 MB of free space on the hard disk for installation.
WARNING: All connections between the GasClam and a PC and all software settings must be performed outside
the hazardous areas.
Function
The software is used to configure the GasClam 2 for logging, downloading logging data, performing analysis and
exporting data for more detailed analysis in other programs such as spreadsheets. The software is also used to
perform periodic “Bump Test” and “User Calibration”.
The main settings are the logging interval, variable logging interval
programme, the number of samples (sample count), the outlet gas
venting method and whether a borehole water level sensor is fitted.
To help make data analysis easier the software can set each GasClam 2
a “friendly” name. If more than one GasClam 2 is being used on a
monitoring site it is good practice to also label each GasClam 2 so that
they are not put in the wrong boreholes.
Power Supply Options
The GasClam 2 can use 4 approved power sources:
• 2x 1.5 V Alkaline-Manganese Duracell - MN1300 (Alk-Mn) (logging interval 3 minutes to 24 hours)
• 2.6 V Nickle Metal Hydride rechargeable battery pack (Ni-MH) (logging interval 3 minutes to 24 hours)
• 7.2 V Lithium non-rechargeable battery pack (Li) (logging interval 15 minutes to 24 hours)
• 12 V External dc power supply (Ext) (logging interval 3 minutes to 24 hours)
The GasClam 2 can operate as either a stand-alone logger or linked to a data acquisition system.
The Ni-MH battery packs are rechargeable lasting up to a month with a 1-hour logging interval. The Li packs are
non-rechargeable primary cells that can last up to 3 months with a 1-hour logging interval. The lifespan of individual
types of battery packs depends on the logging interval, GasClam 2 sensor configuration, operating temperature
and for rechargeable packs in particular, age and time since they were last charged.
An external power supply is particularly useful if shorter logging intervals are required (sampling up to every 3
minutes) when a battery pack would not last a month and frequent site visits are not feasible. This option is also
advantageous if remote monitoring is required either using the optional modem (which can also be powered
externally) or external telemetry (see section “External Power”). Note: Moisture Filter life is dependent on logging
interval.
The GasClam 2 will automatically select the power source and adjust accordingly (see Software Manual).
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External Power Supply
WARNING: The external power supply and communications can only be designed and installed by persons
suitably qualified and trained while adhering to national and local standards and regulations.
A GasClam 2 can be powered by an external power supply using either
the optional “External Power and Com Cable” which is 10m long or for
longer distances using the optional “Junction Box” and a suitable cable.
Either cable is then connected to the external power supply via barriers
which must have the following parameters to maintain intrinsic safety.
External Power Supply Parameters
Nominal Voltage Un ................................ = 12V DC ±10%
Power Output Pn ..................................... ≧ 5W
Maximum Voltage Uo ............................. ≦ 15.6V
Capacitance Co ........................................ ≧ 600pF + C cable
Impedance Lo .......................................... ≧ 0.2mH + L cable
Remote Data Acquisition
Stand-alone with external power
If the stand-alone solution requires monitoring with more frequent logging
intervals which would be outside the capability of the battery packs it is also
possible to power the GasClam 2 via the optional “Junction Box”.
The external power supply and barriers must have the parameters defined
above to maintain intrinsic safety.
Custom remote data with external power
The optional “External Power and Com Cable” (as above) can also be used to
access logging data or change GasClam 2 settings from outside the hazardous
area. Cable length is 10m which is the maximum guaranteed distance for the
GasClam 2 RS232 interface.
Battery Life and Sample Count
The battery life and the number of samples taken will depend on the battery type, the operating temperature,
humidity and the logging interval.
All batteries will have reduced maximum lifespans at low temperatures.
Power Supply
Voltage
[V]
Capacity
[Ah]
Operating
range
[°C]
Maximum Number of Samples for
Logging Interval
(1)
Nominal Battery Life
in days for Interval
(2)
5 min
15 min
1 hour
15 min
1 hour
Alkaline Duracell 2x
3.0
13.5
0 – 50
197
963
963 8 32
Ni-MH Rechargeable
2.6
9.5
0 – 40
680
666
666 5 23
GasClam 2s without batteries
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Li Long Life
7.2
19.0
0 – 50
na
2937
2937
24
98
The average number of samples for each logging interval is shown (1). This value can vary depending on operating
temperature, the number and type of gas sensors fitted in the GasClam 2 and the state of the filters. These values
are for temperatures at 20 °C with the maximum number of sensors and clean filters.
The “Nominal Battery Life” (2) is a conservative calculation of the number of days a battery will last under
“nominal” conditions (battery is fully charged at the start of logging, operating temperature is 20 °C, the filters are
clean) and using all the sensors. This value is 80% of the average value for 15min and 1 hour logging intervals.
Other factors such as relative humidity can also affect the battery lifespan (see below).
Alkaline Batteries
The GasClam 2 is fitted with Alkaline batteries for initial testing and checks. However, for normal field work it is
recommended to use either the Ni-MH rechargeable or Li long-life battery packs. The Duracell batteries can be
stored in the instrument case as a reserve and can be used when the rechargeable battery has not been charged
and the GasClam 2 must be deployed immediately. Alkaline batteries have a long “shelf life” but do not use after
the date shown on the battery. Short logging intervals will reduce the maximum number of samples taken.
Ni-MH Rechargeable
The Ni-MH rechargeable battery packs should be fully charged using the charger provided (see instructions) and
used for logging as soon as possible. Rechargeable batteries do not have a long “shelf life” as they will self-
discharge over time.
This also means that battery life is not proportional with an increase in logging interval, e.g. if the logging interval
is increased from 1 hour to 12 hours the nominal battery life will not increase 12 times to 276 days (9 months).
The NiMH batteries self-discharge at a rate of 15% - 20% per month.
To obtain the maximum working life from the Ni-MH battery packs it is recommended that they are always first
fully discharged and then charged using the charger provided (see Charger instructions). Also Ni-MH battery packs
should be charged at least once every 6 months even if they are not being used.
Li Long-Life
The Long-life battery pack will last up to 3 months at an hourly logging interval. Only the Li battery pack has a
restriction on the minimum logging interval that can be used and that is 15 minutes.
The Li battery pack has a built-in fuse to maintain intrinsic safety and if the GasClam 2 is switched on/off rapidly
using the Push-button cable in rare cases this can cause the fuse to blow. If the GasClam 2 does not react with a Li
battery pack first check the battery using a voltmeter.
Adhere to the conditions of use and safety instructions enclosed with the Li battery packs.
The Effects of Temperature and Humidity on Sample Count
To ensure that the gas sample is dry before measurement by the CH4 and CO2 sensors a Moisture Filter is fitted in
the GasClam 2. Over time this will hydrate and its ability to remove moisture will decrease. If moisture is not
successfully removed, concentration readings can be affected. The amount of samples that can be taken will
depend on temperature and humidity. The table below shows how many samples can be taken at 90% Relative
Humidity (RH) at different temperatures (90% RH is assumed to be worst case).
Temperature °C
1°C
5°C
10°C
15°C
20°C
25°C
30°C
35°C
38°C
Samples at 90% RH
3455
2620
1850
1320
950
700
520
390
330
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Typically, temperatures in a borehole will not go below 3°C and will not exceed 15°C however, this will depend on
installation. If the GasClam 2 is used above ground then temperatures can vary more widely.
The Ni-MH rechargeable battery on the GasClam 2 lasts approximately 670 samples (hourly sampling). To ensure
the GasClam 2 does not take more samples than the filters capacity use the table above to set the sample count
(see Software “Setup”), e.g. if the borehole is at 30°C set the sample number to less than 520.
It is unlikely that RH in a borehole will exceed 90% all the time and to help assess how to manage the filter after
the first installation there is an indicator system. The indicators work differently below 30°C and above 30°C (see
section “Servicing”).
Temperatures Below 0°C
If the temperature drops below 0°C and there is high humidity the valves in the GasClam 2 may freeze and prevent
correct sampling and a pump error will be flagged. This will not damage the GasClam 2; when temperature rises
above 0°C it will function correctly (see section “Fault Finding”).
Typically the GasClam 2 is installed in boreholes below the ground and the GasClam 2 will not go below 0°C due to
ground heat. If the GasClam 2 is installed above the ground, insulation or a heater will be needed to prevent
freezing. If you are unsure about your GasClam 2 installation contact your local supplier.
The Effects of Water on a GasClam 2
The GasClam 2 is designed to:
• measure gas concentrations,
• measure borehole and atmospheric pressure,
• allow a venting pathway between the borehole and atmosphere,
• the GasClam 2 software enables a selection of venting options.
To measure gas concentrations the gas must be dry and measurements of atmospheric pressure should not include
the pressure of overlying water. As the GasClam 2 can be in a position liable to flooding from above (flooded
Headworks) and below (borehole water level) it is necessary to:
• carrying out simple preventive and remedial maintenance and
• being aware of the limitations of data gathered under flood conditions.
How the GasClam 2 Prevents Water Entering From Below
To prevent water entering the GasClam 2 from below a water proximity sensor is situated below the gas inlet. If
water rises up the borehole and comes into contact with the proximity sensor the GasClam 2 will pause logging.
When water level drops GasClam 2 will resume logging after 1 hour.
To prevent water from reaching the gas inlet barb and flooding the GasClam 2, the Filter Cover creates an air
pocket at the base of the GasClam 2 (Always check to see if the cover is not damaged or cracked as this could then
let water in).
The air pocket should stop water from reaching the gas inlet for at least 7 days when the GasClam 2 is completely
submerged with 20 cm of water above its head. If the GasClam 2 is immersed for longer, the User must check to
ensure water has not reached the inlet barb before restarting the GasClam 2. If the User suspects that water may
have reached the gas inlet they must contact their local service centre.
NOTE: The water proximity sensor works on the principle of conductivity and when water comes into contact
with the sensor it completes the circuit switching off the GasClam. If a non-conducting fluid, such as oil, is
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floating on top of the water in a borehole the water proximity sensor will not detect it and therefore it can be
sucked into the GasClam.
How the GasClam 2 Prevents Water Entering From Above
To prevent water reaching the vent pathway the Snorkel Set should
always be attached to the Vent Barb. The open end tube should be
supported so it is located at the top of the Headworks to reduce the
chance of water ingress.
In locations where the Headworks are likely to be flooded the Vent Barb
must be replaced with the Vent Plug. The supplied box spanner is used
to remove the Vent Barb and the supplied Alan key (no.4) used to insert
the Vent Plug and washer.
If the Vent Plug is inserted it should be configured in the software (see
software “Setup”). Atmospheric pressure will not be recorded in this
mode.
Optimising GasClam 2 Performance
Read the ‘Cross sensitivities and sensor performance’ section to
understand how each gas is detected and the implication of
environmental conditions on their detection.
Understand the implication on sampling and bump testing if a 5% CO2
sensor is installed (see section “Technical Specification”).
Periodically (on a monthly basis) the GasClam 2 should be removed from
the borehole if installed for long periods and checked (see section “Site
Visit”).
If conditions of 85% RH and 40°C have persisted for more than 10 days
the H2S, CO and O2 sensors may need to be reconditioned (see section
“Service”).
The GasClam 2 software (see Software Manual) offers a selection of
venting options during logging.
Start Monitoring
Changing Batteries
WARNING: For reasons of intrinsic safety, batteries MUST NOT be changed within hazardous areas. Always
ensure you are in a safe area before carrying out any type of work on your GasClam.
WARNING: To maintain the Unit’s certification and intrinsic safety use ONLY GasClam approved batteries.
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The battery compartment is accessed by loosening the four (no.5) Allen key
bolts on the Battery Cover Plate – note that the bolts do not unscrew
completely, they remain with the plate.
To replace batteries follow the instructions below:
1) First clamp the Battery Cover Plate so that the spring under
the plate does not exert unequal force on the bolts
ensuring that bolts loosen smoothly without forcing the
thread.
This can be done by clamping the plate with the thumb on the
“GasClam 2” logo and the rest of the fingers under the head.
2) Loosen the bolts first by applying force on the long end of
the Allen key in a cross pattern (1,2,3,4).
3) When the bolts are loose and while still clamping the
Battery Cover Plate unscrew fully.
4) To remove the batteries tilt the GasClam 2 until they slide
out.
5) Replace with only GasClam 2 approved batteries positive
terminal facing DOWN into the GasClam 2.
6) Check the integrity of the O-ring, if damaged it MUST be
replaced. The O-ring should be checked every time the
batteries are replaced.
7) When the O-ring is resting on the battery compartment
push the cover plate down evenly to ensure it travels down
square. This will prevent damage to the O-ring.
The cover plate must sit flush with the head of the GasClam 2
otherwise the intrinsic safety of the unit will be compromised.
8) Again clamp the plate with the thumb on the “GasClam 2”
logo and the rest of the fingers under the head.
9) First tighten the bolts by hand taking care that the bolts
tighten smoothly without crossing the threads.
10) When the bolts are finger tight use the Allen Key, alternate
between the bolts in a cross pattern (1,2,3,4) applying
moderate force on the short end of the Allen Key.
11) Repeat this several times tightening the bolts in a cross
pattern.
12) When the bolts are tight repeat one more time applying
moderate force on the long end of the Allen key.
If this procedure is not followed carefully, damage to the O-ring may be caused compromising the intrinsic safety
of the Unit.
WARNING: Do not connect or disconnect any cables in hazardous areas and do not use non-approved
equipment in hazardous areas such as laptops, notebooks and mobile phones.
4
1
3
2
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Connecting the GasClam 2 to a PC
Whilst the GasClam 2 is outside the hazardous area it can be programmed using a computer with the GasClam 2
software (see Software Manual). This is done using the Serial Communication Cable (supplied) and an RS232-USB
converter (not supplied).
1. Remove the cap from the Com Port on the GasClam 2.
Carefully connect the Serial Communication Cable
ensuring that the two red dots are aligned, then push
for a firm click.
2. Connect the Serial Communication Cable to the RS232
converter and connect to the USB port of the computer
(the RS232 convert will need to install drivers the first
time it is connected to the computer).
3. Start the GasClam 2 software either using the desktop
icon or from the start menu.
Check Voltages and Settings
The GasClam 2 will automatically detect the power source when it is first
inserted and adjust accordingly (see software manual).
After new batteries have been inserted check in the “Home” window
that the appropriate power source has been selected by the GasClam 2
in the line “Power Source” and that “Power Status” meter is showing the
correct voltage:
Alkaline Duracell: New above 3 V.
Ni-MH rechargeable: Fully recharged 2.5 – 2.7 V.
Li Long-life: New battery pack 7.0 – 7.2 V.
After ensuring that the battery type and voltage corresponds with the
newly fitted batteries, proceed to set up the GasClam 2 for the
monitoring application (and specific borehole) by clicking on the “Setup”
button in the “Home” window.
In the “Setup” window first check that the time and date are correct,
that if a water level sensor is fitted it is selected, that the correct venting
option is selected and then add a friendly name for the GasClam 2. After
configuring the GasClam 2 then setup the logging intervals and sample
counts required. When finished, write the setup to the GasClam 2.
Check the settings in the “Home” window then run one test sample.
Afterwards check that the status is “Sleeping”. Switch off the software,
disconnect the Serial Communication Cable and replace the Com Port
Cap on the GasClam 2.
Check that the black Barb Caps have been removed.
The GasClam 2 is ready for deployment.
Installing the GasClam 2 in a Borehole
Using the Lifting Handle carefully lower the GasClam 2 into the borehole
and check that it sits in the standpipe smoothly with the Rubber Collar
forming a good seal.
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Ensure that either a Snorkel Set or the Vent Plug is fitted.
If a water level sensor is to be used first hook it and then connect it to
the GasClam 2 outside the hazardous area. Take the GasClam 2 with the
water level sensor to the borehole. First lower the sensor and then the
GasClam 2 again ensuring a good fit with the Rubber Collar and the
standpipe (see water level sensor instructions).
Turning the GasClam 2 On
The only way to manually start the GasClam 2 when it has been deployed
is to use the supplied Push-Button Cable. It connects to the Com Port on
the head of the GasClam 2 in the same way as the Serial Communication
Cable.
It is intrinsically safe and is the ONLY piece of equipment that can be
connected and disconnected from the Unit in a hazardous area.
To start the GasClam 2, hold the button down for two seconds, the red
LED will flash rapidly indicating the GasClam 2 has started logging and is
currently sampling.
After sampling has finished (approximately 3 minutes) the red LED
flashes intermittently indicating that the GasClam 2 is Logging but
between Samples.
To stop the GasClam 2, press the button for two seconds, the red LED
will stop flashing indicating that the GasClam 2 is “Sleeping”.
The Push-Button cable can also be used to perform occasional checks of
the state of the GasClam 2 without the need to take the Unit out of the
borehole
It is recommended that when a GasClam 2 is deployed and logging is first
started to check that the LED starts to flash rapidly indicating that
sampling has started and then to wait until the LED starts to flash
intermittently indicating that the first sample has finished before
disconnecting the Push-Button Cable.
Leaving the Site
When leaving a borehole check that:
1. the Snorkel Set is fitted correctly and above the flood level,
2. the Com Port Cap is fitted to prevent dust entering the socket,
3. the Headworks cover has been securely fitted.
Site Visits
WARNING: Do not connect or disconnect any cables in the hazardous area and do not use non-approved
equipment in the hazardous area such as laptops, notebooks and mobile phones.
WARNING: Before removing the GasClam from the field it must be run at least once (purged) in a nonhazardous atmosphere to clear any hazardous gasses from the unit.
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Regular Checks
It is recommended that at least once a month (or sooner depending on the power option and logging interval) the
GasClam 2 is safely removed from the borehole and inspected outside the hazardous area in a dry location. When
removed:
• Inspect the GasClam 2 for any signs of wear and tear (especially the Filter Cover Tube).
• Check for signs of water ingress prior to purging the unit (see section “Effects of Flooding”).
• If there are no signs of water ingress, purge the unit.
• Download and backup the logging data.
• Check the data for any faults (see Software Manual) and if required take appropriate action.
• Change batteries if required and check the integrity of the battery O-ring.
• Check and change the Moisture Filter if required (see section “Service”).
• Perform a Bump Test on the sensor channels if required (see Software Manual).
Note: If conditions of 85% and higher RH and +40°C are expected to have persisted for more than 10 days the H2S,
CO and O2 sensors may need to be reconditioned (see section “Specification”).
Data Retrieval
Manual Download
Remove the GasClam 2 from the borehole using the Lifting Handel. Take
the GasClam 2 outside the hazardous area.
Under no circumstances take or connect a laptop to the GasClam 2 in a
hazardous area!
Place the GasClam 2 on a clean dry surface and wipe the head around
the Com Port Cap if dirty. Connect the GasClam 2 to the PC using
procedure previously described.
Download the data using the software as described in the Software
Manual. Sampling will cease when the GasClam 2 logging memory is full.
Ensure memory is cleared for extended sampling once logging data has
been checked, validated and backed-up.
Leaving the Site
When leaving the site after a regular visit, check as before. If leaving the site after monitoring is complete ensure
that the borehole is secured safely and not open.
Calibration, Servicing and Storage
Unit Calibration and Service
To ensure correct and accurate operation it is recommended that the GasClam 2 should be recalibrated and
serviced every 12 months (or sooner depending on the logging interval and sensor configuration). The GasClam is
ATEX certified for use in potentially explosive areas, therefore it must only be serviced and fully calibrated by an
authorised GasClam 2 service centre. Failure to do so will invalidate the warranty and may invalidate the
certification.
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Storing the GasCalm when Not In Use
When the GasClam 2 is not in use it should be cleaned thoroughly, run for several cycles in clean preferably dry
air, the batteries removed and placed in the instrument case. If it is intended to store the Unit for a longer period
it is recommended to replace the caps on the barbs to stop moisture and dust ingression. When storing for a longer
period (more than 3 month) the GasClam 2 should be fitted with 2x 1.5 V Alkaline-Manganese Duracell - MN1300
(Alk-Mn) batteries to ensure the functionality of the electronics
Filter Management
Below 30°C the bottom indicator turns pink after approximately 40% of
filter life and the top turns pink after 50% of filter life. For 15°C and 90%
RH, the indicators will change in accordance to the table below. Above
30°C and high humidity the indicators on the Moisture Filter correspond
to less samples.
Environmental
conditions
Max number
of samples
Bottom indicator
turns pink after:
[samples]
Top indicator
turns pink after:
[samples]
15°C - 90% RH
1320
490
730
38°C - 98% RH
300
240
360
To assess if the filter needs to be replaced when the batteries are
changed inspect the filter indicators. If both indicators are blue, the filter
does not have to be replaced. The table below shows what actions to
take depending on the state of the top and bottom indicators with
respect to temperature and humidity.
Bottom
indicator
Top
indicator
Action at 15°C - 90% RH
Action at 38°C - 98% RH
Blue
Blue
Don’t replace
Don’t replace
Pink
Blue
Don’t replace
(probably need to replace next time)
Replace
Pink
Pink
Replace
Check GasClam 2 for signs of moisture in the unit.
Contact local service centre if any signs of
moisture within the GasClam 2 or tubing.
Replace
Check GasClam 2 for signs of moisture in the unit.
Contact local service centre if there are any signs
of moisture within the GasClam 2 or tubing.
If sampling in the same borehole again reduce
the total number of samples taken so both
indicators do not turn pink.
If both indicators turn pink after 1 battery life (670 samples) contact your local supplier for sampling advice.
Inspecting and Replacing the Moisture Filter
WARNING: The GasClam must never be operated without the
Moisture Filter.
To inspect the Moisture Filter follow the instructions below:
1. Place the GasClam 2 on a table with the head
down.
Top
Bottom
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2. Carefully unscrew the black plastic Filter Cover
using both hands placed on the knurled sections for
better grip.
3. Check the colour of the indicators.
4. Check the sealing O-rings, if damaged replace
immediately.
5. If the result is ok then screw the Filter Cover back
on.
To replace the Moisture Filter follow the instructions below:
1) Place the GasClam 2 on a table with the head down.
2) Carefully unscrew the black plastic Filter Cover.
3) Using both hands, put the thumbs beneath the filter and push
it up and out of the connecting barb and nozzle.
4) Leaning the new filter to right and first connect the tube
(Tygon) to the barb.
5) Push the tube firmly down on the barb.
6) Lean the filter back upright making sure the other inlet sits
down on the nozzle.
7) Push the filter completely down firmly from the top.
8) Run the “Leak Test” from the software to check that the
system is correctly sealed
9) Check the sealing O-rings, if damaged replace immediately.
10) If the result is ok then screw the Filter Cover back on.
User Serviceable Parts
Battery compartment O–ring:
When changing the batteries always inspect the O-ring on the Battery
Cover Plate, if there is any sign of damage replace.
Moisture Filter
The GasClam 2 must never be operated without a Moisture Filter! Follow the
advice regarding Moisture Filter management and the instructions on how to
change the filter.
Filter Compartment O–rings:
When inspecting the Moisture Filter check O-ring 1 and 2, if there are any signs
of damage replace the corresponding O-ring immediately.
Snorkel
The snorkel should be checked regularly, if there is any damage replace immediately.
Rubber Collar
Inspect the collar regularly, if there is any signs of damage replace immediately.
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User Spare Parts
Item
Description
1
Serial Communication Cable (2m)
2
Push-Button Cable (1m)
3
Rubber Collar
4
Moisture Filter (18ml)
5
Snorkel Set
6
Snorkel Filter
7
Vent Plug Set
8
Barb (Vent, Inlet and Outlet)
9
Battery Pack NiMH L1X2 (2.4V - Rechargeable)
10
Battery Charger ECH 1.1
11
Battery Charger Power Supply
12
Battery Pack Lithium Primary Li72-190F
13
Moisture Filter Cover (Plastic)
14
Communication Port Cap and Lanyard
15
Water Level Sensor Cap and Lanyard
16
O-Ring 1 and O-Ring Battery Cover (ᴓ 032 x 2 mm)
17
O-Ring 2 (ᴓ 033 x 2 mm)
18
Battery Cover Plate (Complete)
19
Allen Key no.5 (Battery Cover)
20
Box Spanner no.7 (Vent Barb)
21
Allen key no.4 (Vent Plug)
22
ATEN – USB-RS232 Converter
9
10
15
2
1
22
11
1
16
12
18
19
6
3
16
17
13
20
8
14
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Fault Finding
Software
The primary fault finding tool is the “Error Log” which can be checked after downloading a set of logging data and
the “Error Box” in the software’s home window (see Software Manual).
The Effects of Flooding on Data and the GasClam 2
When the GasClam 2 unit is not taking any samples it has a protection rating of IP68, however immersion will effect
data and may require subsequent corrective action.
These effects and requirements will differ whether immersed from above (flooded Headworks) or from below (rise
in borehole water level) see table below:
Flooded Headworks
Remedial Action
Preventive Maintenance
Effects on
data
Should Vent breather be submerged:
• Atmospheric pressure readings will be
incorrect.
• Scheduled venting will be ineffective.
To replace lost atmospheric data
use borehole pressure as an
approximate replacement or use
data from another source.
If the chamber is known to flood, or is
already full of water:
• Choose another chamber.
• Or replace the Snorkel with a Vent
Plug.
Effects on
GasClam 2
If submerged for an extended period the
vent pipe may become flooded.
The vent breather may become clogged
by dirty water.
When the GasClam 2 is visited
check data and call the service
centre if atmospheric pressure
looks strange, they will advise.
If chamber is liable to flooding:
• Replace Snorkel Filter each visit.
• Position the Snorkel at a higher
location.
Flooded Borehole
Remedial Action
Preventive Maintenance
Effects on
data
Should water reach the base of the Unit
the inflow and outflow valves will close,
no samples will be taken:
• Borehole pressure readings will be
incorrect.
• Gas concentration readings will be
incorrect.
Data points for the set logging
interval will be marked when
samples have not been taken.
If borehole water level is known to be
high or is already full of water:
• Choose another chamber.
• Or extend the borehole above ground
level.
Effects on
GasClam 2
Should water reach the base of the
GasClam 2 the water proximity
(flooding) sensor will react and the
inflow and outflow valves will close and
no samples will be taken.
A flooding error will be flagged up in the
software.
None
Every time a GasClam 2 is removed from
a borehole the inlet barb should be
checked to see if a water droplet is on it.
If so dry with a cloth.
If there is any chance that water may
have entered the inlet contact your local
service centre and DO NOT start or
purge the GasClam 2.
Potential Problems when GasClam 2 used Below 0°C
If the temperature of the body of the GasClam 2 drops below 0°C and there is high humidity the valves inside may
freeze and prevent correct sampling. This will not damage the GasClam 2 and when temperatures rise above 0°C
it will function correctly.
Another indication that the valves have frozen is that the
O2 sensor will go off scale either positively or negatively
and the atmospheric pressure reading will also
dramatically increase.
The graph illustrates a cycle between -10 and 10 °C at 98%
RH. When the temperature reaches -5°C O2 goes off scale
positively and atmospheric pressure increases by 20 mBar.
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When temperature rises the valve thaws and O2
concentrations are correct.
Technical Specification
General Specification
GasClam 2
V8
Material
Outer case and frame: High Quality Stainless Steel. Filter Cover: PP plastic
Weight
7.5 kg (16.8 lb)
Dimensions
Overall length 90 cm, head ᴓ 11 cm
Ingress Protection
IP 68 (continuous submersion, 20 cm above the GasClam 2 head for 7 days)
Working Environment
0 to +40 °C (32 to 104 °F) RH up to 95%
Storage Environment
+5 to +25 °C dry conditions
Power Supply Options
2x 1.5 V Alkaline-Manganese Duracell - MN1300 (Alk-Mn) – LR20
2.6 V Nickle Metal Hydride rechargeable battery pack (Ni-MH) – L1X2
7.2 V Lithium primary battery pack (Li) – Li72-190F
12 V External dc power supply (Ext) – 12V dc ± 10% max 660 mA
Power Consumption
Sampling max 300 mA @ 12V
Sleep 60μA @ 12V
Logging Interval
3 minutes to 24 hours (Lithium battery packs 15 minutes to 24 hours)
Internal Memory
Maximum 30,000 date/time stamped sample set, depending on configuration
If errors are recorded maximum memory is reduced to 15,000 sample sets
Internal Memory Mode
Sampling will stop when the memory is full.
Date and Time
Internal clock
Sensors
5x gas sensors optional), 2x pressure, 1x temperature (built-in), water level (optional)
Communication
RS232 – 115200 baud
Configuration and Setup
GasClam 2 Software
Approvals
CE, EMC
ATEX
-20 °C to +50 °C Alkaline batteries
-10 °C to + 40 °C Ni-MH rechargeable battery pack
-20 °C to +50 °C Li Long-life battery pack
-20 °C to +50 °C External
Protection
II 2G Ex d ib [ib] IIB T4 Gb
Certificate number
FTZU 07 ATEX 0105 X
IECEx (Pending)
-20 °C to +50 °C Alkaline batteries
-10 °C to + 40 °C Ni-MH rechargeable battery pack
Protection
Ex d ib [ib] IIB T4 Gb
Certificate Number
IECEx FTZU 09.0026
CSA C US (Pending)
-20 °C to +50 °C Alkaline batteries
-10 °C to + 40 °C Ni-MH rechargeable battery pack
Protection
Class 1, Zone 1, Ex d ib IIB, T4 Class I, Zone I, AEx d ib IIB, T4
Certificate Number
2320892
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25
Patent
European and Worldwide Patent granted
Dimensions
The main dimensions of the GasClam 2 are show below (mm):
Built-in Sensors
Sensor
Type
Range
Resolution
Barometric Pressure
Piezoelectric
800 - 1250 mBar
1 mBar
Borehole Pressure
Piezoelectric
800 - 1250 mBar
1 mBar
Temperature
Internal Chip
-20 to +50 °C (-4 to 122 °F)
0.1°C (1°F)
Water depth (optional)
Piezoelectric
0 - 27 m
0.01 m
Gas Sensor Specifications
Position
Sensor
Type
Range
Resolution
Accuracy
5
CO2
Infrared
0 - 100 %
1% above 50%
0.5% below 50%
± 2% FSD
5
CO2
Infrared
0 - 5%
-
-
4
CH4
Infrared
0 - 100 %
1% above 50%
0.5% below 50%
± 2% FSD
4
CH4 0 - 5%
-
-
3
O2
Electrochem
0 - 25 %
0.10%
± 5% of reading
± 1 digit
2
CO
Electrochem
0 - 2000 ppm
1 ppm
<± 3ppm at 0
± 5% at 250 ppm
± 10% full scale
2
H2S
Electrochem
0 - 100 ppm
1 ppm
<± 1 ppm at 0
± 2.5% at 50 ppm
2
Dual H2S/CO
CO
Electrochem
0 - 500 ppm
1 ppm
<± 3ppm at 0
± 3% at 250 ppm
H2S
Electrochem
0 - 200 ppm
1 ppm
<± 1 ppm at 0
± 2% at 100 ppm
1
VOC
PID
0 - 4000 ppm
1 ppm
± 5% of reading
± 1 digit
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Note: Specifications obtained under laboratory conditions of gas flow, temperature and humidity. Field performance is
dependent on the correct installation procedures being followed, environmental conditions, frequent sensor cleaning and
regular calibration. Some of the sensors have cross sensitivity, for more information contact your local supplier. Details are
subject to change without notice.
Cross sensitivities and Sensor Performance:
100% Carbon Dioxide (CO2)
Carbon Dioxide is measured using an infrared sensor tuned to C=O. There are no other gasses commonly found in
the subsurface that absorb infrared radiation at this wavelength, so the reading will not typically suffer from cross
sensitivity.
5% Carbon Dioxide (CO2)
When sampling concentrations up to 5% the sensor will read 90% of the real value after one sample (typically this
will be within error of the sensor). For example, if you are sampling every hour and the real concentration changes
from 0% – 2.5% in 1 hour (which is unlikely) the senor will read approximately 2.25%. In reality if low concentrations
are present they will change much more gradually i.e.:
• Sample 1 Real concentration 0.0 Measured 0.000
• Sample 2 Real concentration 0.1 Measured 0.090 (within error)
• Sample 3 Real concentration 0.3 Measured 0.279 (within error)
• Sample 4 Real concentration 0.8 Measured 0.750 (within error)
When concentration decreases the reading will also be 90% of the real value after 1 sample. Below are examples
when 4.7% CO2 has been sampled and how the sensor/filter clears down in air.
• Sample 1 4.701 4.738 4.671
• Sample 2 0.326 0.29 0.468
• Sample 3 0.071 0.037 0.042
Methane (CH4)
Methane is measured using an infrared detector tuned to C-H bonds. The sensor is calibrated using certified
methane calibration gas and will give accurate readings providing no other C-H compounds are present. If
additional hydrocarbons are present they will contribute to the reading.
Oxygen (O2)
The oxygen sensor is a Galvanic sensor and very specific. It has a little cross sensitivity with CO2, 5 % CO2 only
causes a 0.1% change in reading. Humidity has a small effect on output, between 0 % to 95% RH the % O2 change
is < 0.7 %. The sensor can work between 5 - 95 % RH continuously and 0 - 99% short term.
Single Carbon Monoxide (CO)
The Single CO sensor has a filter to reduce the cross sensitivity with H2S, NO2, NO and SO2, the following are the
filter capacities for the given gases:
• H2S 250,000 ppm - hours
• NO2 600,000 ppm - hours
• NO 20,000 ppm - hours
• SO2 300,000 ppm - hours
50 ppm NO will read < 5 ppm
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400 ppm H2 @ 20°C will read < 60 ppm
400 ppm C2H2 will read < 25
Single Hydrogen Sulphide (H2S)
The cross sensitivities with these gases are:
• 5 ppm NO2 will read approximately -1 ppm on the H2S Channel
• 50 ppm NO will read < 5 ppm on the H2S Channel
• 20 ppm SO2 will read < 4 ppm on the H2S channel
• 400 ppm CO will read < 4 ppm on the H2S channel
• 10 ppm Cl2 will read < -25 ppm on the H2S channel
Dual CO / H2S Sensor
The CO and H2S sensors are electrochemical sensors and suffer from cross sensitivity to other gases that may be
found in the subsurface. The carbon monoxide sensor suffers in particular from the cross sensitivity with H2S, H2
and NO.
The cross sensitivities with these gases are:
• 15 ppm H2S will read < 6 ppm on the CO channel
• 35 ppm NO will read < 0.1 ppm on the CO channel
• 100 ppm H2 will read approx. 20 ppm on the CO channel
The hydrogen sulphide sensor is especially cross sensitive to the following:
• 5 ppm NO2 will read approximately -1 ppm on the H2S Channel
• 35 ppm NO will read < 1 ppm on the H2S Channel
• 5 ppm SO2 will read < 1 ppm on the H2S channel
• 300 ppm CO will read < 6 ppm on the H2S channel
If the sensors have been exposed to gases they are cross sensitive for long periods it may take some time for the
sensors to recover. The sensors can be checked after exposure to these gases by setting the GasClam 2 to sample
every 5 minutes in clean air and the concentrations should return to zero and stabilise. If you suspect a cross
sensitivity problem please contact your supplier for further advice.
Additional CO / H2S sensor performance information
If the GasClam 2 is located in a zero oxygen environment for longer than 24 hours the CO and H2S sensor
performance may be hindered. To return the channels to optimal performance the sensor needs to be left exposed
to an oxygenated environment for the same length of time as it was deprived of oxygen for.
Above 85% RH and 40°C a maximum continuous exposure of 10 days is recommended. Where such exposure
occurs the sensor will recover normal electrolyte volumes when allowed to rest at lower % RH and temperature
for several days.
If very accurate CO or H2S measurements are required it is recommended that a single CO or H2S sensor is used.
Volatile Organic Compounds (VOC)
The VOC sensor is a mini photo ionisation detector (PID) and is sensitive to any VOCs that have an ionisation
potential less than 10.6 eV. The sensitivity of the sensor depends on the VOC present. The sensor is calibrated to
isobutylene and its response to other VOCs can be calculated using that compounds response factor. A response
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factor is a number, which relates the PID response to a particular VOC, to the PID response from the calibration
gas (normally isobutylene). If the response of a PID to a particular VOC is eight times smaller than it is for the same
concentration of isobutylene, then the response factor would be 8. Similarly, if the response factor for a particular
VOC is 0.5, the response is twice that for isobutylene at the same concentration.
Concentrations greater than 4% CH4 and CO2 will attenuate the response of the PID sensor.
Some VOCs after ionisation may stick to the PID lamp reducing the amount of ultraviolet light available for future
measurements. Before each PID measurement is made the lamp is turned on for 30s to burn the residual VOCs off.
However, some VOCs may be more persistent and not completely removed, if this happens the PID response will
decrease. To recondition the lamp, set the GasClam 2 to sample every 3 minutes and run for 1 hour in clean air,
then perform a bump test. If the sensor has not completely recovered try reconditioning for longer. If this does
not work contact your local service centre.
Disclaimer: Information in this [manual, document…] is subject to change without notice and does
not represent a commitment on the part of Ion Science. No claims, promises or guarantees are
made about the accuracy, completeness, or adequacy of the information contained herein.
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