Ampcontrol Gasguard 65-6551-CH4 Series User manual

User Manual Part Number: 165714
Version: 6, March 2019
Designed and manufactured in Australia by Ampcontrol Pty Ltd
CATALYTIC METHANESENSOR
ATEXCERTIFIEDMODEL
UserManual

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GASGUARD CH4 GAS SENSOR USER MANUAL
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WARNING!
The warning symbol highlights a potential risk of injury or death.
Please share these warnings with other operators.
CAUTION!
The caution symbol highlights a potential risk of damage to
equipment.
Please share these cautions with other operators.
NOTE
The note symbol highlights key information.
Please share these notes with other operators.
ENVIRO
The enviro (environmental) symbol highlights areas which may have an
impact on the surrounding fauna and/or flora.

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Copyright Notice
The Ampcontrol Gasguard Sensor described in this document is the propertyof AMPCONTROL PTY LTD.
It is furnished under a license agreement and is to be used only in accordance with the terms of the
agreement.
No part of the hardware or documentation may be reproduced, transmitted, transcribed, stored in a
retrieval system, or translated into any language or computer language, in any form or by any means,
without prior written permission of AMPCONTROL PTY LTD.
Disclaimer
While every effort has been made to assure the accuracy and clarity of this document, AMPCONTROL
PTY LTD assumes no liability resulting from any omissions in this document, or from misuse of the
information obtained herein. The information in this document has been carefully checked and is believed
to be entirely reliable with all of the necessary information included. AMPCONTROL PTY LTD reserves
the right to make changes to any products described herein to improve reliability, function, or design, and
reserves the right to revise this document and make changes from time to time in content hereof with no
obligation to notify any persons of revisions or changes. AMPCONTROL PTY LTD does not assume any
liability arising out of the application or any use of any product or circuit described herein; neither does it
convey license under its patent rights or the rights of others.
Before You Begin
Thank you for purchasing the Ampcontrol Gasguard Sensor.
WARNING!
In the interests of safety and correct equipment operation, please
take the time to read and understand the content in this manual.
Ampcontrol Contact Details
7 Billbrooke Close, Cameron Park, NSW, 2285
P [phone] | F [phone]
EMAIL: [e-mail]
WEB: ampcontrolgroup.com

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TABLE OF CONTENTS
1 SAFETY AND OTHER WARNINGS..................................................................6
1.1 Safe Use of Equipment..............................................................................6
2 RECEIVING AND STORAGE............................................................................7
2.1 Receiving...................................................................................................7
2.2 Inspection..................................................................................................7
2.3 Storage after Delivery................................................................................7
2.4 Unpacking of Equipment............................................................................7
3 PRODUCT OVERVIEW ....................................................................................8
3.1 Sensor Details ...........................................................................................9
3.2 Amplifier Electronics PCB........................................................................10
3.3 Enclosures...............................................................................................10
4 INSTALLATION...............................................................................................11
4.1 General Warnings....................................................................................11
4.2 Product Safety Markings..........................................................................11
4.3 Recommendations...................................................................................12
4.4 Sensor Location.......................................................................................12
4.5 Mandatory Installation Practices ..............................................................12
4.6 Mechanical Installation Information..........................................................13
4.7 Electrical Installation Information .............................................................14
5 COMMISSIONING AND CALIBRATION .........................................................15
5.1 Preliminary Checks..................................................................................15
5.2 Gasguard Display Panel..........................................................................15
5.3 Sensor Calibration...................................................................................16
5.4 Zero Calibration.......................................................................................17
5.5 Span Calibration......................................................................................17
6 SERVICE, MAINTENANCE & DISPOSAL.......................................................18
6.1 Equipment Service...................................................................................18
6.2 Equipment Maintenance..........................................................................19
6.3 Disposal...................................................................................................20
7 SPECIFICATIONS ..........................................................................................21
8 EQUIPMENT LIST ..........................................................................................21
APPENDIX A: ATEX CERTIFICATION ..............................................................22

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TABLE OF FIGURES
Figure 3.1: Gasguard CH4 Sensor Stainless Steel Housing...............................10
Figure 4.1: Catalytic Sensor Dimensions............................................................13
Figure 4.2: Electrical Connection Diagram .........................................................14
Figure 4.3: Analogue Output Maximum Loop Resistance...................................14
Figure 5.1: Gasguard Sensor Control Panel.......................................................17
TABLE OF TABLES
Table 1: Sensor Cell Cross Sensitivity..................................................................9
Table 2: Gasguard Sensor Display Status Codes...............................................15
Table 3: Manufacturer’s Periodic Maintenance Recommendation ......................19
Table 4: Corrective Maintenance –Possible Faults............................................20

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1 SAFETY AND OTHER WARNINGS
For safety reasons, the Gasguard CH4 Sensor must be installed, operated and serviced only by
competent personnel. Please read and understand this instruction manual completely before installing,
operating or servicing this equipment. Failure to install or operate this instrument in accordance with the
instructions contained in this manual may create hazardous operating conditions.
WARNING!
The sensors should not be stored in areas that contain solvent vapours.
Some of these vapours are known to create false "high" zero points and
may even damage the sensor electrodes. Similarly, the sensor should
not be exposed to high levels of solvent vapours while in operation.
WARNING!
This equipment has been designed to detect explosive gases and
vapours and to give warning before they reach dangerous conditions.
1.1 Safe Use of Equipment
The equipment supplied has been designed and manufactured to ensure safe operation. The equipment
must only be used within the design parameters.
The instructions within this manual must be observed as an aid towards achieving the safest possible
installation.
Persons responsible for installation, maintenance, or operation, must observe the following
instructions:
1.1.1 Changes to Equipment
Changes in the design and modifications to the equipment are not permitted. Unauthorised changes
made to the hardware or operating firmware will void the manufacturer's warranty, and may
compromise the integrity of the system into which it is installed and other connected equipment.
1.1.2 Equipment Knowledge
Experience with, or understanding of, this equipment is essential for the safe installation and removal of
the equipment. Therefore, please read and understand this manual prior to use. Competency based
training courses are recommended and are available on request.
1.1.3 Manual Handling
Precautions have been taken to ensure all equipment is safe to handle and free from sharp edges.
However care should always be taken when handling enclosures and gloves should be worn.
1.1.4 Installation
Correct operation and safety depend on the Gasguard CH4 Sensor and associated equipment being
installed correctly. Mechanical and or electrical installation and maintenance of plant and equipment
must only be carried out by appropriately qualified personnel and must be tested thoroughly prior to
operation.
1.1.5 Operation
As safety depends on the Gasguard CH4 Sensor functioning correctly it is highly recommended that all
safety functions of the unit be periodically tested to ensure correct operation.

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2 RECEIVING AND STORAGE
2.1 Receiving
All possible precautions are taken to protect the equipment against damage or losses during shipment,
however before accepting delivery, check all items against the packing list or bill of loading. If there is
evidence of physical damage, notify Ampcontrol immediately.
Notify Ampcontrol immediately in case of any discrepancies to the packing list. Keep a record of any
claims and correspondence. Photographs are recommended.
Where practicable do not remove protective covers prior to installation unless there are indications of
damage. Boxes opened for inspection and inventory should be carefully repacked to ensure protection of
the contents or else the parts should be packaged and stored in a safe place. Examine all packing
boxes, wrappings and covers for items attached to them, retain and store any approval documentation
for your safety file as applicable prior to wrapping being discarded.
2.2 Inspection
Equipment that is found to be damaged or has been modified away from its published specification must
not be used. Please contact Ampcontrol if the equipment is suspected to be different than that ordered or
if it does not match the published specifications.
2.3 Storage after Delivery
When the equipment is not to be installed immediately, proper storage is important to ensure protection
of equipment and validity of warranty.
All equipment should be stored indoors between 0-40˚C, preferably on shelves and protected from
moisture and sunlight.
2.4 Unpacking of Equipment
The method of packing used will depend on the size and quantity of the equipment. The following
cautions should be interpreted as appropriate.
CAUTION!
Take care when unpacking crates as the
contents may have shifted during transport.
ENVIRO
The disposal of packaging materials, replaced parts, or components
must comply with environmental restrictions without polluting the soil,
air or water.
Ensure that any timber and cardboard used as packaging is disposed
of in a safe and environmentally responsible manner.
Where possible, dispose of all waste products i.e. oils, metals, plastic
and rubber products by using an approved recycling service centre.

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3 PRODUCT OVERVIEW
Ampcontrol’s Gasguard Flammable Gas Sensor/Transmitter is supplied complete with an amplifier and a
Liquid Crystal Display.
The Gas sensor is housed in a cast stainless steel enclosure, has been approved to be intrinsically safe
and is suitable for use in a Zone 0 hazardous area. A remote head version with up to ten metres of cable
is also available for use on mobile machinery such as roof bolters and continuous miners.
Key Features
Rugged Construction
Reliable
Certified Intrinsically Safe –Ex ia
LCD Display
Non-Intrusive Closed Case Calibration
NOTE
This manual provides commissioning, calibration and maintenance
instructions for the Ampcontrol Gasguard Sensor Units. Because the
units are passive monitoring devices, operating instructions are not
applicable to this equipment.
NOTE
The chemical symbols for toxic-gases and oxygen are used extensively
throughout this manual.
The Gasguard sensor units consist of:
Catalytic - Methane Sensor (CH4)
Amplifier PCB
For which the following instructions and diagrams are included in this manual:
Amplifier PCB Description
Sensor Wiring Diagrams
Stainless Steel Housing Enclosure Dimensions
Unique part numbers in accordance with the following scheme identifies the sensor unit configurations:
See section 8 for Catalytic sensor Item Numbers.
NOTE
In the part numbers listed, CH4 represents the chemical symbol for
methane, the gas detected by this sensor.

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3.1 Sensor Details
3.1.1 Methane Gas Sensor
The Methane Gas Sensor, which operates on the catalytic combustible gas detection principle, is a
small platinum element coated in a catalyst. Electrical current is passed through the platinum wire and
the potential of the catalytic element is monitored by a simple Wheatstone Bridge arrangement.
Combustible gases, once in contact with the heated catalytic surface of the measuring element, react
and cause the surface temperature of the element to rise. Any increase in temperature affects the
resistance of the platinum wire, causing a small shift in potential across the Wheatstone Bridge
proportional to the concentration of the combustible gas. The sensor is temperature compensated and
provides a 4/20mA linear output.
3.1.2 Sensor Cell Cross Sensitivity
Methane gas sensors positively detect the presence of all flammable gases. It is unable to distinguish
the difference between gases so the sensor will display a reading if any flammable gas is present. The
table below details the cross sensitivity data for a methane sensor.
Table 1: Sensor Cell Cross Sensitivity
Gas
Concentration
Reading (%v/v)
Acetic Acid
4.0%
1.45
Acetone
2.6%
2.5
Ammonia
15%
6.25
Benzene
1.2%
2.0
n-Butane
1.8%
2.5
Carbon Monoxide
12.5%
4.0
Chlorobenzene
1.3%
1.7
Ethanol
3.3ppm
2.95
n-Hexane
1.2%
2.0
Hydrogen
4.0%
4.0
Methane
5.0%
5.0
Methanol
6.7%
4.25
n-Pentane
1.4%
2.0
Propane
2.1%
2.5
Toluene
1.2%
2.0
3.1.3 Poisoning of Sensors (Contamination)
High levels of or long exposure to certain compounds may poison the catalytically active detector
filament thereby reducing or destroying its sensitivity.
Among these compounds are halides, sulphur compounds, leaded petrol, silanes, silicates and other
produces with silicon. Products such as aerosol sprays, polishes, waxes and lubricants with silicones
and non-catalysed silicone rubbers such as “silastic”, phosphate esters and hydraulic fluids all damage
catalytic sensors.
CAUTION!
Exposure to Hydrogen Sulphide gas (H2S) may affect the performance
of the detector by reducing its sensitivity to methane. If the sensor is
exposed to H2S gas then the detector must be recalibrated.

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3.2 Amplifier Electronics PCB
The purpose of the amplifier electronics is to convert the low-level electrical output of the sensor into a
signal capable of driving external indicator equipment such as the Ampcontrol Gasguard 4 Channel
Controller.
The Gasguard amplifier electronics are designed to operate as a 3-wire unit with connections provided
for input power, power supply return and current loop signal output.
The electronics require 12VDC operating voltage and transmits a signal in the range of 4 - 20mA. The
4mA signal level indicates a zero gas concentration. The 20mA signal indicates that the sensor cell has
detected a full span gas concentration. ZERO and SPAN adjustment reed relays located on the PCB are
used for calibration of the sensor.
3.3 Enclosures
Stainless Steel Housing
The standard Stainless Steel Housing, Item Number 23-6550LB, incorporates the Sensor Cell and
Amplifier PCB. The housing is robust and is corrosion resistant. It is suitable for almost all applications
and provides for easy installation and maintenance. When properly used it gives many years of efficient
operation.
Figure 3.1: Gasguard CH4 Sensor Stainless Steel Housing

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4 INSTALLATION
4.1 General Warnings
These instructions have been designed to assist users of the Gasguard CH4 Sensor with installation.
Before the unit can be installed, there are a number of things that need to be considered and understood
to prevent incorrect or unsafe operation of the unit or the system into which it is installed.
Along with relevant competence, and an understanding of the target application, the following points
should be considered:
4.1.1 Ensure that the information provided in this user manual is fully understood.
It is extremely important that the limitations and functionality of the Gasguard CH4 Sensor are
understood to prevent incorrect installation and use from creating a potentially dangerous risk. If in
doubt as to the nature of the limitations or their implication, consult a competent authority such as a
supervisor or Ampcontrol technical representative.
4.1.2 Ensure that the application into which the Gasguard CH4 Sensor is being installed
has been properly defined, designed and approved.
Any system intended to mitigate the risk of injury needs to be properly designed and implemented.
Such a system must be the result of structured risk analysis with the outcomes used to define the
system requirements. These requirements, in turn, will guide the choice of instrumentation, logic
solvers and actuators needed to implement the system. Understanding the needs of the system will
ensure proper selection of equipment.
4.1.3 Ensure that the Gasguard CH4 Sensor will properly perform the required functions
within the system design.
It is important to understand how the Gasguard CH4 Sensor is intended to interact with other
equipment within a system. For safe and reliable use, it is crucial that neither the Gasguard CH4
Sensor logical operation nor its signalling be compromised by incompatibilities with connected
equipment.
4.1.4 Modifications of any form to the Gasguard CH4 Sensor are prohibited.
The Gasguard CH4 Sensor as supplied has been designed and manufactured to comply with the
requirements of protection standards. If modifications of any form are made to the Gasguard CH4
Sensor, the equipment may no longer be fit for use. If any modifications or damage to the [Gasguard
CH4 Sensor is evident, do not use the equipment and contact Ampcontrol for advice.
4.2 Product Safety Markings
The ATEX Gasguard methane sensor carries the following information as part of its front panel labelling:
Equipment Type: Gas Sensor/Transmitter
Product Type: Gasguard Series 65-6551CH4
Cert No: Baseefa09ATEX0204X
Ex marking: I M1 Ex ia I [-20C ≤ Ta ≤ +40C]
These markings provide information identifying the sensor type, certificate number and its safety
classification. This information, along with that provided on the certificate must be taken into account
when installing, operating and maintaining this sensor.

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4.3 Recommendations
Select a suitable central location for mounting with good access. The location should be as clean
and dry as practicable and at a temperature as close to 20C as practicable.
Mount the sensor unit in a position that minimises the risk of mechanical damage.
Mounting should be to a vertical surface, allowing for easy wiring access and subsequent
servicing. It is essential that the sensor be positioned to take into account the expected flow of
the gas to be measured (see Section 4.4 Sensor Location).
The sensor should not be mounted with the gas detection port pointing upwards. Positioning the
sensor in this manner could result in the gas entry holes and filter membranes becoming blocked
by water or debris. If this occurs, the sensor will likely suffer reduced sensitivity and/or extended
response times.
It is recommended that the sensor is not mounted next to electrical cables or equipment that is
likely to produce large amounts of electrical or magnetic switching noise.
4.4 Sensor Location
The relative density or buoyancy of the gas or vapour with respect to air is a very important
consideration. This determines its propensity to rise or fall when released into the atmosphere.
Gases or vapours with buoyancy less than air will tend to rise from the source of release. Conversely,
gases or vapours heavier than air will tend to fall from the source of release.
Over time, all gases will disperse and become mixed into the general surrounding atmosphere. Methane
is lighter than air and can therefore become trapped in elevated areas where low air currents prevent
mixing. Places such as corners, roof or cable spaces are examples.
For monitoring in areas where there are no air currents, mount the sensor as high as possible. For areas
that are ventilated and have good airflow, positioning is not as critical since general mixing will occur.
For these areas it is recommended to locate the sensor around, or just above head height. For
applications requiring specific detection characteristics such as at the point of potential release, proper
analysis of the site should be undertaken to determine the optimum sensor location.
4.5 Mandatory Installation Practices
The following information must be adhered to when installing the Gasguard CH4 Sensor. Failure to
adhere to this information may give rise to unsafe operation.
Using the Gasguard CH4 Sensor in a manner that exceeds its electrical, functional or physical
specifications, or in a way that is contrary to its operating restrictions, may create risks to personnel
and/or equipment resulting in injury or death.
The sensor must be powered from an intrinsically safe source of power. This may be either:-
oAn intrinsically safe power supply, or,
oA safe-area located, non-intrinsically safe power supply via the use of an appropriate
zener barrier.
The sensor must not be directly powered from a non-intrinsically safe power supply (i.e. without
the use of an intervening appropriate barrier).
Connections to and from this sensor must only be to equipment with compatible entity
parameters.
The installation of this sensor must be carried out by suitably trained and qualified personnel.
Certification and identification labels fixed to this sensor must not be damaged, removed or
covered before, during or after installation.
Modifications must not be made to any part of the sensor. As supplied, the unit is built to, and
complies with the standards against which it has been certified. Modifications to its construction
will render the unit incompatible with its certificate.
Complete and accurate records of the installation must be kept as part of the site dossier.

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4.6 Mechanical Installation Information
4.6.1 Enclosure Dimensions
Figure 4.1: Catalytic Sensor Dimensions
4.6.2 Mounting Arrangements
The Gasguard CH4 Catalytic Sensor is a panel mounted unit, see enclosure dimensions for mounting
point configuration.
(TOXIC)
(FLAMMABLE)
170
198

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4.7 Electrical Installation Information
Electrical connections to the catalytic sensor are by means of a cable encapsulated into the sensor and
terminated with a cable mounted plug. The sensor plugs into the Amplifier electronics PCB (Connector
J4 within the sensor enclosure). The amplifier PCB is fitted with plug/screw connectors. This allows the
connector to be unplugged from the PCB to attach the wiring and then be plugged back into the board.
A second wiring assembly connects the supply and signal connections from the incoming terminals to
the Amplifier electronics PCB (Connector J5 within the sensor enclosure). Connector J5 is the
connection point for incoming cables. Figure 4.2 shows these electrical connections.
Figure 4.2: Electrical Connection Diagram
The loop resistance that the Gasguard Sensor’s analogue output can drive is limited by the input supply
voltage. This relationship is depicted in Figure 4.3.
Figure 4.3: Analogue Output Maximum Loop Resistance
Gasguard
65-6551
Sensor
Transmitter
123
4-20mA DC
-
+
0V
Signal
+V Supply
4
Maximum Loop Resistance at 20mA
0
100
200
300
400
500
600
910 11 12 13 14 15
Input Supply Voltage (V)
Ohms

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5 COMMISSIONING AND CALIBRATION
Commissioning is the process of carrying out initial checks, adjustments and calibration prior to placing
the system into operation for the first time.
Sensor calibration, although forming part of the commissioning process, is also performed periodically
throughout its operational life. Calibration is also required immediately following any repair to the sensor.
During commissioning and subsequent recalibration, it is important to ensure that appropriate steps are
taken to prevent the sensor output signal from initiating a fault, warn or alarm condition, or
inappropriately driving an equipment control function. Consult the relevant equipment user manuals for
specific details on how to isolate alarms and functions.
The sensor, as supplied has been factory calibrated to traceable standards. However, before putting the
sensors into operation, it is important to verify this calibration. This is especially important if the
instruments are commissioned sometime after delivery.
5.1 Preliminary Checks
Perform the following preliminary checks:
Verify that electrical connections are correct and that they comply with the appropriate standards.
Apply power to the sensor.
Check the voltage applied to the Amplifier electronics is between 12VDC and the maximum
permitted under the conditions of certification.
Verify that the sensor is displaying a gas reading and has not entered a fault condition. The
reading may not sit at zero initially since the sensor needs to stabilise from the point of applying
power.
5.2 Gasguard Display Panel
The Gasguard display provides a number of indications relating to its operational status. The table below
lists these along with their meaning.
Table 2: Gasguard Sensor Display Status Codes
Display
Description
-777
There is no sensor plugged into the amplifier or supply voltage low
-888
Sensor is faulty/expired
-999
Amplifier needs reconfiguration
Er
Error has occurred
CAL
Calibration mode initiated (display blinks when in calibration mode)
SAU
Calibration settings have been saved
PU
Powering Up

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5.3 Sensor Calibration
Before the start of calibration, the sensor should be powered up and left to stabilise for at least two
hours.
NOTE
Calibration can only be carried out once the installation is complete and
fault free.
Following the stabilisation period, sensor performance can be checked. If performance is within the
limits of error given in the product specification, no calibration is required.
5.3.1 Calibration Gas
Sensor zero calibration must only be carried out using industrial grade clean air that is within its
expiry date and carries a standards traceable specification.
Sensor span calibration must only be carried out using methane that is within its expiry date and
carries a standards traceable concentration.
To achieve the required concentration for calibration purposes, methane is mixed or ‘balanced’ with a
‘carrier’ gas. This carrier gas must be air for the Gasguard’s catalytic sensor to operate correctly.
Methane balanced with nitrogen must never be used to verify or calibrate the sensor since this will
inhibit the function of the catalytic sensor bead.
Calibration gas should ideally be 50% of full scale. However, sometimes, due to practical restraints and
safety reasons, the gas may need to be less than 50%. Concentrations of less than 25% of full scale
should not be used in order to avoid potential calibration inaccuracies.
5.3.2 Flow Rate
Calibration gas should be applied to the sensor at a rate of approximately 0.5 to 1.0 litres per minute. It
is not necessary to leave the gas flowing to the sensor for any longer than is needed for the output to
stabilise and the calibration adjustment to be made.
5.3.3 Safety
Because sensor calibration involves the use of gas, appropriate safety procedures must be observed in
regard to its safe handling and use.
Proper regard to site safety practices must be given, including the creation of safe work method
statements where necessary. Specific conditions relating to the site into which the sensor is located
may also need to be considered. It may be necessary to use equipment that is approved for use within
the area where the sensor is located.

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Figure 5.1: Gasguard Sensor Control Panel
5.4 Zero Calibration
Perform a zero calibration as follows, noting that the gas must be flowing for the duration of the
operation:
a) Apply clean air to the sensor via the calibration hood and allow the reading to stabilise.
b) Place the magnetic tip of the calibration pen over the CAL symbol (1) for 5 seconds.
c) Now that the CAL mode is accessed place the magnetic tip over the ZERO symbol (3) for 5
seconds.
d) The display should have a zero reading. To save the zero setting place the magnetic tip over the
CAL symbol (1) for 5 seconds.
e) The sensor display (5) will show SAV to confirm that it has saved the zero setting.
f) Turn off the gas flow to the sensor
5.5 Span Calibration
Perform a span calibration as follows, noting that the gas must be flowing for the duration of the
operation:
a) Apply methane to the sensor at the rate of 0.5 to1 litre per minute and allow the reading to
stabilise.
b) If the reading lies outside the error limits given in the product specification, adjustment will be
necessary.
c) To adjust the sensor reading so that it reads the correct value for the applied methane
concentration, enter calibration mode by placing the magnetic tip of the Calibration pen over the
CAL symbol (1) for 5 seconds.
d) Place the magnetic tip of the pen over the UP symbol (4) to increase the display reading and over
the DOWN symbol (6) to decrease the display reading. Use these actions to set the reading to
the correct value.
e) To save the calibration value, place the magnetic tip over the CAL symbol (1) for 5 seconds.
f) Turn off the gas flow to the sensor.

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6 SERVICE, MAINTENANCE & DISPOSAL
6.1 Equipment Service
A number of external system based checks should be completed on a regular basis. These ‘routine
inspections’ must be carried out by suitably trained people with knowledge of the Gasguard CH4 Sensor
and the systems into which it is fitted. Routine inspections may take the form of either visual-only checks,
or visual and ‘hands-on’ checks.
6.1.1 Visual Only Inspections
A basic visual inspection focuses on looking at the installation for signs of physical damage, water or
dust ingress and the condition of cables and labels. This type of inspection may involve opening
cabinets to gain access to the Gasguard CH4 Sensor and other equipment. This level of inspection
may also include cleaning display windows that have become obscured by dirt.
Observations would typically be:
Check that equipment enclosures, cable trays, conduits, etc. are in good order with no physical
damage.
Check that sealed wall boxes are free from water and dust ingress internally. Door seals are in
good condition.
Check that connected cables are free from cuts, abrasions and obvious signs of damage. Cable
restraints are in good order and correctly fitted.
Check that labels on equipment, wall boxes and cables are present and in good condition
(especially certification labels).
Check that no modifications have been carried out to installed equipment.
6.1.2 Hands-On (Detailed) Inspections
A more detailed inspection would include all of the elements of a visual inspection, plus some checks
that cover the integrity of connections, fixtures and fittings.
In addition to basic visual observations, more detailed integrity checks would involve:
Verify that equipment housings, wall boxes and other mechanical fixtures are secured in place.
This includes terminal box lids, tightness of cable glands, integrity of wall-box mountings, security
of equipment fixing to walls/DIN rails etc.
Verify all electrical connections are secure with no loose screw terminals or DIN rail terminals not
fitted to rails etc.

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6.2 Equipment Maintenance
WARNING!
The Gasguard CH4 Sensor has no user-serviceable parts.
All repairs must be carried out by Ampcontrol only.
If a fault develops, return the Gasguard CH4 Sensor to Ampcontrol for
repair. It is essential that no attempt be made to repair the Gasguard
CH4 Sensor as any attempt to dismantle or repair the Gasguard CH4
Sensor can seriously compromise the safety of the unit and voids
product warranty.
6.2.1 Periodic Maintenance
Periodic maintenance involves scheduled checks to ensure the instrument remains operating safely
and performs within its specification. The following maintenance schedule is recommended.
Specific site schedules may exist to perform visual, close and detailed inspections of equipment. These
will include checks for both basic mechanical integrity and electrical/performance checks. The schedule
given below is the manufacturer’s recommendations.
Table 3: Manufacturer’s Periodic Maintenance Recommendation
Time Frame
Maintenance
Daily
Verify operation by visually checking the reading on the respective
control unit/monitor. Investigate any abnormal deviations from Zero
reading.
Clean any dirt from display window to maintain a clear view of readings.
This should be done carefully to avoid scratching the window and
rendering the display unreadable.
Monthly
Check the Zero reading in fresh air or by applying nitrogen/clean air.
Readjust as necessary.
Check the Span calibration with a known concentration of methane.
Readjust as necessary.
As Required
Replace the catalytic gas sensor whenever it becomes impossible to
adjust to Zero, or when the Span adjustment is insufficient to enable
adjustment to the calibration gas value. If this occurs, recalibrate the unit
as described in Section 5 Commissioning and Calibration.
Following Power
Removal
If power has been removed from the unit for a long period of time, a re-
commissioning check should be carried out.

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6.2.2 Corrective Maintenance
During maintenance and subsequent recalibration, it is important to ensure that appropriate steps are
taken to prevent the sensor output signal from initiating a fault, warn or alarm condition, or
inappropriately driving an equipment control function. Consult the relevant equipment user manuals for
specific details on how to isolate alarms and functions.
There are only two active replaceable units in the sensor system, the Amplifier Electronics PCB and the
gas sensor. Therefore, fault isolation is limited to the following possible faults and remedies.
Table 4: Corrective Maintenance –Possible Faults
Fault
Rectification
4-20mA output not
functioning
a) Verify all connections are correct and are not damaged or
disconnected.
b) Verify that the fault does not lie with connected equipment such
as controllers etc.
c) Verify the supply voltage applied to the Amplifier PCB is within
specification.
d) Check for loose plug and terminal connections.
e) If the above checks indicate no faults, replace the Amplifier
electronics PCB.
Sensor cannot be
Spanned or Zeroed
a) Check the supply voltage to the sensor is within specification.
b) Check for loose plug and terminal connections.
c) Verify the calibration gas being used is of the correct type and is
within its expiry date
d) Verify that the gas entry ports are free from obstruction by water
or debris.
e) If the above is correct and the problem persists, replace the
sensor
f) If the sensor still cannot be Spanned or Zeroed, replace the
Amplifier PCB.
Erratic Output
a) Check that voltage and polarity applied to the Amplifier PCB is
correct. Also, check that there are no severe voltage swings,
indicating an intermittent fault in the field wiring or control unit.
b) Check for loose plug and terminal connections.
c) If the above is correct and the problem persists, replace the
sensor.
d) If the output is still erratic, replace the Amplifier PCB.
6.3 Disposal
ENVIRO
The electronic equipment discussed in this manual must not be
treated as general waste. By ensuring that this product is disposed of
correctly you will be helping to prevent potentially negative
consequences for the environment which could otherwise be caused by
incorrect waste handling of this product.