Ampcontrol GASGUARD 65-6550 Series User manual

Version:7, February 2019
User Manual Part #: 161297
Designed and manufactured in Australia by Ampcontrol Pty Ltd
GASGUARD
CH4CATALYTIC DETECTOR UNIT
User Manual

Ampcontrol Pty Ltd – ABN 28 000 915 542
GASGUARD CH
4
DETECTOR USER MANUAL
GSB093 Version 7 – FEB/19
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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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4
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Copyright Notice
The Ampcontrol GasGuard detector unit described in this document is the property of 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 from the Ampcontrol GasGuard range.
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: [email protected]
WEB: ampcontrolgroup.com

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4
DETECTOR USER MANUAL
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TABLE OF CONTENTS
1 SAFETY AND OTHER WARNINGS..................................................................7
1.1 Safe Use of Equipment..............................................................................7
2 RECEIVING AND STORAGE............................................................................8
2.1 Receiving...................................................................................................8
2.2 Inspection..................................................................................................8
2.3 Storage after Delivery................................................................................8
2.4 Unpacking of Equipment............................................................................8
3 PRODUCT OVERVIEW ....................................................................................9
3.1 Methane Gas Sensor...............................................................................10
3.2 Amplifier PCB ..........................................................................................11
3.3 Stainless Steel Enclosure........................................................................11
3.4 Sensor Wiring Assembly..........................................................................11
4 PRODUCT OPERATION.................................................................................12
5 INSTALLATION...............................................................................................13
5.1 General Warnings....................................................................................13
5.2 Mandatory Installation Practices..............................................................13
5.3 Installation Guidelines..............................................................................14
5.4 Mechanical Installation Information..........................................................15
5.5 Electrical Installation Information .............................................................16
6 COMMISSIONING AND CALIBRATION .........................................................19
6.1 Preliminary Checks..................................................................................19
6.2 System Calibration...................................................................................19
6.3 Zero Calibration.......................................................................................20
6.4 Span Calibration......................................................................................20
6.5 Response time testing .............................................................................21
7 SERVICE, MAINTENANCE & DISPOSAL.......................................................22
7.1 Equipment Service...................................................................................22
7.2 Equipment Maintenance..........................................................................23
7.3 Disposal...................................................................................................23
8 SPECIFICATIONS ..........................................................................................24
9 EQUIPMENT LIST ..........................................................................................25

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TABLE OF FIGURES
Figure 3.1: Anti-vibration clip.....................................................................................11
Figure 4.1: Sensor / Transmitter User Interface ........................................................12
Figure 5.1: Catalytic detector dimensions .................................................................15
Figure 5.2: Catalytic sensor unit wiring diagram........................................................17
Figure 5.3: Remote catalytic sensor unit wiring diagram...........................................18
Figure 6.1: GasGuard detector control panel ............................................................20
TABLE OF TABLES
Table 1: Methane cross-sensitivity............................................................................10
Table 2: Sensor / Transmitter User Interface Descriptors..........................................12
Table 3: GasGuard Display Codes............................................................................12
Table 4: Gas Density Relative to Air .........................................................................14
Table 5: Nominal Resistance Values for Typical Wire Sizes .....................................16
Table 6: Corrective Maintenance Checks..................................................................23

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DEFINITIONS
Term Definition
Detector
Complete apparatus purchased by end user comprised of a sensor head and
amplifier PCB in a stainless steel enclosure that detects gas and converts to a 4-
20mA signal as well as displays a reading on the LCD screen
Sensor head The assembly attached to the bottom of the detector which houses the sensor cell
Amplifier PCB
The PCB inside the detector that amplifies the sensor cell signal into a usable 4-
20mA loop
CH4Methane
NATA National Association of Testing Authorities, Australia

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1 SAFETY AND OTHER WARNINGS
For safety reasons, the GasGuard detectors 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 these instruments in accordance with the
instructions contained in this manual may create hazardous operating 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 detector 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 detector functioning correctly it is highly recommended that all
safety functions of the product be periodically tested to ensure correct operation.

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4
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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 the 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 specifications
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 3-20˚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 Methane Sensor / Transmitters are supplied complete with an amplifier and a
Liquid Crystal Display.
The Transmitter/Sensor assembly is an IEC Ex ia Group I certified assembly. The Certification is based
on the unit being sealed to IP66 in a stainless steel enclosure and the appropriate checks being made on
the Intrinsically Safe Parameters of the overall system the transmitter is connected into.
The Transmitter and Sensor can be mounted as an integral device but there is also an option to mount
the sensor separately up to 10m from the transmitter. In the remote configuration the sensor is factory
fitted with a type 2S cable which is potted directly into the sensor assembly.
The sensor is designed to provide a standardised output applicable for the gas range. This signal is not
for direct connection to other devices and so the amplifier PCB in the transmitter housing is used to
condition the signal, provide calibration functions and produce a 4-20mA signal.
The transmitter and amplifier assembly is configured in the factory for a specific gas range.
Key Features
•Economical Fixed Gas Sensor / Transmitter
•Rugged Construction
•Reliable
•Certified Intrinsically Safe – Ex ia
•LCD Display
•Non-Intrusive Closed Case Calibration
This document covers the catalytic range of GasGuard detectors. The GasGuard range of detectors
consists of electrochemical, catalytic and infrared sensor types and each provides a linear 4-20mA DC
current output. The full range consists of:
Electrochemical:
•Oxygen (O2)
•Carbon Monoxide (CO)
•Hydrogen Sulphide (H2S)
•Nitric Oxide (NO)
•Nitrogen Dioxide (NO2)
Catalytic
•Methane (CH4)
Infrared:
•Carbon Dioxide (CO2)
The sensor unit part numbers are unique and are identified in accordance with the following scheme:
Model Number 65-6550XXX series is for electrochemical detector units.
Model Number 65-6551XXX series is for catalytic detector units.
Model Number 65-6552XXX series is for Infrared sensor units.
Where XXX represents the chemical symbols for the gas detected by the unit. For example, 65-
6550CH4 is the Model number for an electrochemical unit designed to detect Methane (CH4).

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3.1 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.
3.1.1 Sensor Cell Cross Sensitivity
The cross sensitivity of the methane sensor cells to commonly occurring gases are listed below in Table
1.
Methane (CH4) gas sensors positively detect the presence of all flammable gases. They are unable to
distinguish the difference between gases so the sensor will display a reading if any flammable gas is
present.
CAUTION!
Exposure to Hydrogen Sulphide gas (H2S) may affect the performance
of the Methane sensor (i.e. it may reduce its sensitivity). If the sensor is
exposed to H2S gas then it should be recalibrated.
3.1.1.1 Cross-sensitivity Data Table 1: Methane cross-sensitivity
Methane 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
Methyl ethyl kentone
1.9%
2.0
n-Pentane
1.4%
2.0
Propane
2.1%
2.5
Toluene
1.2%
2.0
3.1.2 Humidity
Sensors can operate in a condensing atmosphere. In such an environment, a thin film of water can form
across the membrane, effectively sealing it and stopping the passage of gas into the sensor. On
evaporation of this water the sensor usually resumes normal operation.
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
products 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 – will all damage
catalytic sensors.

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3.2 Amplifier PCB
The purpose of the Amplifier PCB is to convert the low-level electrical output of the sensor into a signal
capable of driving various types of external indicator equipment such as the Ampcontrol GasGuard 4
Channel Controller.
The Amplifier PCB requires a 12VDC operating voltage and transmits a signal of 4-20mA. At the lower
end of the range, the 4mA signal level indicates a zero gas concentration. At the upper end of the range,
the 20mA signal indicates that the sensor has detected a full span gas concentration. ZERO and SPAN
adjustment reed switches located on the PCB are used for calibration of the instrument.
The CH4 detector latches when the reading is over 5.50% gas concentration. This will result in the
output current latching at 21.6mA. To recover, the detector must have a power cycle, and restart with a
reading less than 5.50%.
NOTE
The CH4 detector latches when the reading is over 5.50% gas
concentration. This will result in the output current latching at 21.6mA.
To recover, the detector must have a power cycle, and restart with a
reading less than 5.50%.
3.3 Stainless Steel Enclosure
The standard stainless steel housing, (shown in Figure 1.1, Page 1), incorporates the methane sensor
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.
3.4 Sensor Wiring Assembly
Sensor and Transmitter assemblies are matched together and cannot be replaced or interchanged by
unauthorised personnel. Connection of any other type of sensor head will render the unit non-
operational.
3.4.1 Anti-Vibration Clip
An Anti-Vibration clip Pt/No. 121647 is fitted to the sensor and power connectors on the rear of the
Amplifier PCB.
Figure 3.1: Anti-vibration clip

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4 PRODUCT OPERATION
The user interface for the Sensor / Transmitter is shown in Figure 4.1, with the numbered items being
explained in Table 2.
Figure 4.1: Sensor / Transmitter User Interface
Table 2: Sensor / Transmitter User Interface Descriptors
Item
Name
Function
1 CAL Button operated using the magnetic calibration tool
2
Sensor Type
Label displaying Sensor Type
3 ZERO Button operated using the magnetic calibration tool
4 UP Button operated using the magnetic calibration tool
5 Screen Used to display the detected gas level or display codes
6 DOWN Button operated using the magnetic calibration tool
Table 3: GasGuard Display Codes
Display
Description
-777 There is no sensor plugged into the amplifier
-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
Power Up
1
3
2
4
6
5

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5 INSTALLATION
5.1 General Warnings
These instructions have been designed to assist users of the GasGuard detector with installation.
Before a GasGuard detector can be installed, there are a number of things that need to be considered
and understood to prevent incorrect or unsafe operation of the detector 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:
5.1.1 Ensure that the information provided in this user manual is fully understood.
It is extremely important that the limitations and functionality of the GasGuard detector is 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.
5.1.2 Ensure that the application into which the GasGuard detector 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.
5.1.3 Ensure that the GasGuard detector will properly perform the required functions
within the system design.
It is important to understand how a GasGuard detector is intended to interact with other equipment within
a system. For safe and reliable use, it is crucial that neither the detector logical operation nor its
signalling be compromised by incompatibilities with connected equipment.
5.1.4 Modifications of any form to the GasGuard detector are prohibited.
The GasGuard detector as supplied has been designed and manufactured to comply with the
requirements of protection standards. If modifications of any form are made to the detector, the
equipment may no longer be fit for use. If any modifications or damage to the detector is evident, do not
use the equipment and contact Ampcontrol for advice.
5.2 Mandatory Installation Practices
The following information must be adhered to when installing any GasGuard detector. Failure to adhere
to this information may give rise to unsafe operation.
Using the detector 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 GasGuard detector must be powered within the specified voltage range.
•The installation of the GasGuard detector must be carried out by suitably trained and qualified
personnel.
•Identification labels fixed to the GasGuard detector must not be damaged, removed or covered
before, during or after installation.
•The installation is to be in accordance with the relevant installation Standards/Codes of Practice.
•Modifications must not be made to any part of the GasGuard detector. As supplied, the unit is
built to, and complies with the relevant standards. Modifications to its construction will render the
unit non-compliant.

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•Complete and accurate records of the installation must be kept as part of the site installation.
5.3 Installation Guidelines
5.3.1 Mounting Location
To ensure continued reliable operation of the sensor system, the following should be considered when
mounting the unit:
•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 reduces the risk of mechanical damage.
•Mounting should be to a vertical surface, pointing downwards, 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.
•Allow sufficient space under the sensor for fitting of calibration cups or accessories.
•Ensure to account for the relative density to air of the gas that is being detected.
5.3.2 Relative Density of Gas Type
The relative density or buoyancy a gas or vapour with respect to air 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 and accumulate in concentrations over
long periods of time. Normal air movements in and around such gas concentrations will have the
inevitable effect of producing zones of highly toxic mixtures.
This knowledge of the characteristics of the gas assists when determining the location of the gas
sensor. See Table 4 for gas density values.
For this reason the methane sensor should be installed as high as practical.
The services of a Risk Assessment Engineer or specialist should be used if additional assistance is
required in selecting the position of, or the number of sensors required for the application.
Table 4: Gas Density Relative to Air
Gas
Density
Hydrogen
Lighter than Air
Ammonia
Methane
Carbon Monoxide
Carbon Dioxide
Heavier than Air
Nitric Oxide
Oxygen
Hydrogen Sulphide
Chlorine

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5.4 Mechanical Installation Information
5.4.1 Enclosure Dimensions
Figure 5.1: Catalytic detector dimensions
5.4.2 Mounting Arrangements
The GasGuard detector is a panel mounted unit. See Figure 5.1 for hole centre locations.
5.4.3 Terminal Layout
The connection terminals for GasGuard detectors are located within the enclosure. In order connect the
incoming cable to the unit the cable must feed through the side mounted cable gland.

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5.5 Electrical Installation Information
5.5.1 Cable Resistance Considerations
The voltage available to the amplifier must be a minimum of 10VDC. The maximum resistance in the 4-
20mA signal to ground at 12V DC supply is 150 Ohms. See Table 5 for typical cable resistance values.
Table 5: Nominal Resistance Values for Typical Wire Sizes
Conductor Area (mm
2
) Resistance (Typical) Loop
Per 500m
0.5 39Ω
1.0 21.2Ω
1.5 13.6Ω
2.5 8Ω
4.0
4.95Ω
5.5.2 Earthing Procedures
Consideration should be given to the earthing of the transmitters and cable screens of the incoming
customer cables.
Normal practice would be to isolate the cable screens at the Transmitter and connect the screens to
earth adjacent to the Control units or power supply to the system.
Remote sensor cable screens should be earthed at the transmitter.

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5.5.3 Catalytic Sensor Unit Wiring Diagram
Figure 5.2: Catalytic sensor unit wiring diagram

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5.5.4 Remote Catalytic Sensor Unit Wiring Diagram
Figure 5.3: Remote catalytic sensor unit wiring diagram

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6 COMMISSIONING AND CALIBRATION
Commissioning is the performance of initial checks, adjustments and calibration prior to placing the
system in operation for the first time. Calibration, however, is not limited to performance of
commissioning. Calibration is also performed throughout the life of the system on a periodic basis and
after major repairs to the system.
During commissioning and subsequent re-calibration, it is vital to ensure that procedures are followed to
prevent any abnormal sensor signal from initiating any fault, warning or alarm status indicator or
equipment control function, on auxiliary equipment connected to the transmitter. Consult the relevant
control unit manual for details of how to do this.
The instruments supplied are NATA calibrated prior to delivery. However, before putting the system into
operation, it is recommended to check the calibration. This is especially important if the instruments are
commissioned sometime after delivery.
6.1 Preliminary Checks
Perform the following preliminary checks:
1. Verify that all connections are correct and installation complete as detailed in Section 5.
2. Check that voltage available to the amplifier is 12VDC.
3. Apply power to the system.
6.2 System Calibration
Before the start of calibration, the system should be left in a powered-up operational (no fault) state for
one hour to allow the gas sensors to stabilise. However, if such a delay is not practical, observe the
display indications with the sensor in a gas free atmosphere, until there is no appreciable display
movement for a period of time. The system should then be sufficiently stable to allow calibration.
Calibration of the methane sensor can only be achieved by using methane gas. The methane calibration
gas should ideally be about 50% of full scale of the relevant monitor. However, sometimes, due to
practical restraints and safety reasons, the gas may be 20% or less of full scale. While calibration at
such a low level is not ideal, the resulting inaccuracies are usually within the safety tolerances for the
system.
Calibration gas should be applied to the sensor at a rate of approximately 0.5 to 1.0 litres per minute. It is
not advisable to leave the gas flow on the sensor any longer than is needed for the output to stabilise
and the calibration adjustment to be made.

Ampcontrol Pty Ltd – ABN 28 000 915 542
GASGUARD CH
4
DETECTOR USER MANUAL
GSB093 Version 7 – FEB/19
Uncontrolled Copy - Refer to Ampcontrol Website for Latest Version
Page 20 of 25
APPROVED FOR EXTERNAL DISTRIBUTION –PROPERTY OF AMPCONTROL PTY LTD –NOT TO BE REPRODUCED IN PART
Figure 6.1: GasGuard detector control panel
6.3 Zero Calibration
Perform Zero Calibration as follows:
1. Ensure that the sensor is in a fresh air environment, and apply zero air via the Calibration Cup.
2. Place the magnetic tip of the calibration pen over the CAL symbol (1) for 5 seconds. The display
will flash every 1-2 seconds while in calibration mode.
3. Now that the CAL mode is accessed place the magnetic tip over the ZERO symbol (3) for 2-3
seconds.
4. The display should have changed to a zero reading. To save the zero setting place the magnetic
tip over the CAL symbol (1) for 5 seconds.
5. The sensor display (5) will show SAU to confirm that it has saved the zero setting. The display
will cease to flash.
6.4 Span Calibration
Perform Span Calibration as follows:
1. Apply CH4calibration gas to the sensor at the rate of 0.5 to 1 litres per minute. Use a calibration
gas of suitable concentration between 40-100% of the range of the unit.
2. To adjust the display so that it reads the correct value for the gas applied enter Calibration Mode
by placing the magnetic tip of the Calibration pen over the CAL symbol (1) for 5 seconds. The
display will flash every 1-2 seconds.
3. 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.
4. Place the magnetic tip over the CAL symbol (1) for 5 seconds once the display reads the correct
value for the gas applied. The display will cease to flash.
5. Shut off the calibration gas. If the Zero calibration is to be checked, wait for the sensor to stabilise
before proceeding.
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