Honeywell 705 Series User manual

Sieger Type 705
CO Sensor and Transmitter for Electrochemical Cells
UL Certified 00705A1731
Operating Instructions

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Ensure that you read and understand these Operating
Instructions BEFORE installing or operating any part of the
equipment.
Please pay particular attention to the Safety Warnings.
WARNINGS
1. To maintain safety standards, regular maintenance,
calibration and operation of this equipment by
qualified personnel is essential. Read and understand
this manual completely before operating or servicing
the equipment. If further details are required which
do not appear in this manual contact Zellweger
Analytics Limited or their agent.
2. TheCodeofPracticeregarding'Selection,Installation
and Maintenance of Electrical Apparatus for use in
Potentially Explosive Atmospheres' must be complied
with at all times. Refer to the appropriate local or
national regulations relative to the installation site.
Elsewhere the appropriate local or national
regulations should be used.
3. Operators must be fully aware of the action to be
taken if the gas concentration exceeds an alarm
level.
CAUTION
To maintain safety standards, regular maintenance,
calibration and operation of the equipment by qualified
personnel is essential.
HELPING TO MAKE A SAFER WORLD

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IMPORTANT NOTICES
1. Zellweger Analytics Ltd can take no responsibility
for installation and/or use of its equipment if this is
not done in accordance with the appropriate issue
and/or amendment of the manual.
2. The user of this manual should ensure that it is
appropriate in all details to the exact equipment to
be installed and/or operated. If in doubt, the user
shouldcontactZellwegerAnalyticsLimitedforadvice.
3. If further details are required which do not appear in
this manual, contact Zellweger Analytics Limited or
one of their agents.
HELP US TO HELP YOU
Every effort has been made to ensure the accuracy in the
contents of our documents, however, Zellweger Analytics
Limited can assume no responsibility for any errors or
omissions in our documents or their consequences.
Zellweger Analytics Limited would greatly appreciate being
informed of any errors or omissions that may be found in the
contents of any of our documents and to this end we include
a form for you to photocopy, complete and return to us so
that we may take the appropriate action.
HELPING TO MAKE A SAFER WORLD

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CONTENTS
Section Page
1. INTRODUCTION 7
1.1 General 7
1.2 Principle of Operation 7
1.3 Accessories 8
2. INSTALLATION 12
2.1 Unpacking 12
2.2 Sensor Orientation 12
2.3 Terminal Housings 12
2.4 Cable Connections 13
2.5 Fitting Sensors 14
3. FITTING ACCESSORIES 16
3.1 Collecting Cone 16
3.2 Weather Protection Housing 16
3.3 Sample Flow Housing 16
4. MAINTENANCE 18
4.1 General 18
4.2 Cleaning 18
5. CALIBRATION 19
5.1 General 19
5.2 Cross Interference From Other Gases 19
5.3 Sensor Life 19
5.4 Calibration Procedure 20
6. GASSING THE SENSOR 21
6.1 Equipment Required 21
6.2 Calibration Gassing Procedure 21
7. REPLACEMENT PARTS 22
7.1 Terminal Housings 22
7.2 Maintenance Spares 22
8. TYPE 705 SENSOR ALTERNATIVE SYSTEMS 23
9. SPECIFICATION 25

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1.1 GENERAL
TheType705CarbonMonoxideSensorisatoxicgasdetector
certified for installation in a hazardous area. This version
uses an Electrochemical (ECC) Sensor, in conjunction with
an electronic circuit to form a three wire 4 - 20mA transmitter.
The sensor comprises an aluminium housing containing an
Electrochemical Cell with a sintered stainless steel disc
forming the face of the sensor. The housing has a 47mm AF
body with a 3/4 NPT mounting thread at one end and an M36
accessory thread on the other end. A plastic Filter Housing
screws on to the accessory thread and holds a Hydrophobic
Barrier in position when accessories are not fitted. There are
a number of accessories available for the 705 Sensor which
utilise the M36 accessory thread. Refer to Section 8 for
alternative systems to which the 705 Sensor can be
connected.
Note: New sensors are despatched with a protection disc
in place of the Hydrophobic Barrier. This disc should
not be removed until the sensor is installed or
commissioned.
1.2 PRINCIPLE OF OPERATION
ThesensorcontainsanElectrochemical Cell. Electrochemical
Cells are dynamic devices which generate a current in
proportion to gas concentration within the cell. As the current
output from the cell is in microamps, it is amplified and
processed by the electronics in the terminal enclosure. The
resulting signal in the range 4 - 20mA (representing
0 - 500ppm CO) can then be connected to equipment in the
safe area to provide alarm and concentration indications.
1. INTRODUCTION

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1.3 ACCESSORIES
1.3.1 General
The following accessories are available for use with the
sensors:
a. Collecting Cone (Figure 2).
b. Weather Protection Housing (Figure 3).
c. Sample Flow Housing (Figure 4).
d. Hydrophobic Barrier.
e. Gassing Point Assembly (Figure 5).
1.3.2 Collecting Cone
The detection of a lighter than air gas is enhanced by the use
of a Collecting Cone. The cone fits onto the sensor accessory
thread in place of the Filter Housing and retains the
Hydrophobic Barrier.
1. INTRODUCTION
Figure 1 Type 705 Sensor and Filter Housing
Mounting Thread
Accessory Thread
Sintered Disc
Hydrophobic Barrier
(fit white side out)
Filter Housing

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A nozzle on the cone permits gassing of the sensor with the
cone in position. The test gas is applied either direct to the
nozzle or via a permanently connected pipeline when the
sensor is fitted in an inaccessible location.
Figure 2 Collecting Cone
Nozzle
6.35 O/D 77.6mm
165mm
42mm
1.3.3 Weather Protection Housing
The Weather Protection Housing, fitted to a sensor installed
in an exposed location, affords protection from driving rain
from the vertical to 30° below the horizontal. When mounted
close to the ground, protection is afforded from heavy rain
rebounding off the ground. It also reduces contamination
from industrial waste and enables the application of a test
gas in high wind speeds without significant error.
The housing is fitted to the sensor accessory thread in place
of the Filter Housing and retains the Hydrophobic Barrier.
Incorporated in the housing is a nozzle to facilitate gassing
the sensor with the Weather Protection Housing in position,
either by direct application to the nozzle or via a permanently
connected pipeline. The nozzle is free to rotate within the
housing to allow removal from the sensor without
disconnecting a permanently connected pipeline, when
changing the Hydrophobic Barrier and cleaning the sensor.
1. INTRODUCTION

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1.3.4 Sample Flow Housing
A Sample Flow Housing provides a means to sample gas
from a closed system, via two pipelines. The flow housing is
fitted to the sensor accessory thread by a locking ring,
enabling removal of the housing without disconnecting the
pipeline. The Hydrophobic Barrier is retained by the housing
and interfaces with a gasket bonded to the housing.
1. INTRODUCTION
Figure 4 Sample Flow Housing
61mm
45mm
31mm
30mm
Figure 3 Weather Protection Housing
50.8mm Dia
25.5mm
51.0mm

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1.3.5 Gassing Point Assembly
This assembly can be fixed at a convenient position and
permanently connected by suitable tubing to an inaccessible
sensor, thus simplifying the application of a test gas when
checking the sensor calibration. A DIN rail mounting
assembly (00785-A-0069) is available to enable five Gassing
1. INTRODUCTION
Point Assemblies to be mounted side by side.
1.3.6 Hydrophobic Barrier
The Hydrophobic Barrier consists of a layer of stainless
steel mesh with a rubber rim, with a Hydrophobic Barrier of
PTFE bonded onto its surface. This MUST be fitted with the
white surface facing outwards.
25mm
Gassing Tube Cap
Stainless Steel
Tube
120mm Dia
Yellow Nylon Block
70mm x 38mm x 19mm
Figure 5 Gassing Point Assembly

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WARNING
The Code of Practice regarding ‘Selection, Installation
and Maintenance of Electrical Apparatus for use in
Potentially Explosive Atmospheres’ must be complied
with at all times. Refer to the appropriate local or national
regulations relative to the installation site.
CAUTIONS
1. Replacement of components by other than Zellweger
Analytics Limited authorised engineers will invalidate
the instrument warranty and certification.
2. The Type 705 Sensor must never be used in
conditions when the flameproof integrity of the sensor
and associated terminal housing is impaired.
3. The sintered disc on the sensor assembly must be
kept free from contaminants, for example oil and
dirt.
2.1 UNPACKING
On receipt the equipment must be carefully unpacked,
observing any instructions printed on the packaging and the
contents checked for deficiencies and transit damage.
2.2 SENSOR ORIENTATION
The sensor must be installed with the sensor facing
downwards. In exposed locations a Weather Protection
Housing should be fitted.
2.3 TERMINAL HOUSINGS
A Terminal Housing (Figure 6) provides a mounting base for
the sensor and contains the associated electronic circuit.
The installation wiring enters the Terminal Housing via
conduit.
2. INSTALLATION

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Cable Entry Conduit
Adalet X1HFC3L
Terminal Housing
Killark Box with
705 Sensor
Cable Entry Conduit
Figure 6 Terminal Housings
2.4 CABLE CONNECTIONS
The sensor is connected by three wires to the terminals on
the pcb.
Connections Colour Code
Counter C Brown
Working W Blue
Reference R White
Two 3-way terminals blocks are provided on the pcb in the
terminal enclosure to enable connections from the sensor
and to equipment in the safe area to be made. For wiring
details see Figure 7.
2. INSTALLATION

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2.5 FITTING SENSORS
WARNINGS
1. Before installing sensors, isolate the power supply
by disconnecting or removing the associated control
module from the installation.
2. All electrochemical cells contain acid or a caustic
solution.Avoid its contact with skin, eyes and clothing.
In case of contact flush with water for at least fifteen
minutes.
CAUTION
The sintered disc on the sensor assembly must be kept
free from contaminants, for example oil and dirt.
Circuit Board Assembly Showing
Adjustment Controls
Offset Zero
RFI Shield Plate
TP3
TP2
Span
Connection Terminals
Figure 7 Connections
2. INSTALLATION

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When fitting a sensor to a metal thread, it is recommended
that the mounting thread should be coated with an approved
anti-seize compound, such as a light petroleum grease.
Refer to Section 8 for alternative systems to which the
sensor can be connected. When replacing a sensor refer to
CAUTION 1 in Section 4 Maintenance Section.
To fit the 705 Sensor, proceed as follows:
(1) Remove the protection disc and fit the accessories as
required. (Refer to Section 3).
(2) Isolate the power supply and wait for five minutes.
(3) Remove the Terminal Housing lid.
(4) Pass the cable into Terminal Housing and fit the sensor
to the housing. To comply with certification
requirements, a minimum of five threads must be
engaged.
(5) Connect the sensor cable to the terminal block.
(6) After mounting the Terminal Housing in the required
location, connect the associated Control Module wiring
to the terminal block (see label).
(7) Fit the shield plate to the standoff pillars, replace and
secure the Terminal Housing lid.
(8) If not already replaced by accessories, unscrew the
Filter Housing, remove the protection disc and replace
the Filter Housing and gasket.
Note: The Hydrophobic Barrier is retained in position by
the Filter Housing, or one of the accessories.
(9) Reconnect to the Control Module.
2. INSTALLATION

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3.1 COLLECTING CONE (00780-A-0032)
To fit the Collecting Cone Assembly to a sensor, proceed as
follows:
(1) Remove the Filter Housing and gasket from the sensor.
(2) Fit the Hydrophobic Barrier, ensuring that the white
surface faces away from the sinter.
(3) Screw the Collecting Cone assembly onto the sensor
accessory thread and tighten firmly by hand.
3.2 WEATHER PROTECTION HOUSING
(00780-A-2076)
To fit a Weather Protection Housing to a sensor, proceed as
follows:
(1) Remove the Filter Housing and gasket from the sensor.
(2) Fit the Hydrophobic Barrier, ensuring that the white
surface faces away from the sinter.
(3) Screw Weather Protection Housing on to sensor
accessory thread and tighten firmly by hand.
3.3 SAMPLE FLOW HOUSING (00780-A-0035)
To fit a Sample Flow Housing to the sensor, proceed as
follows:
(1) Remove the Filter Housing and gasket from the sensor.
(2) Ensure that the Sample Flow Housing is fitted with
gasket (00780-C-0017).
(3) Apply a thin coating of anti-seize compound, such as a
light petroleum grease, to the sensor accessory thread.
3. FITTING ACCESSORIES

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3. FITTING ACCESSORIES
(4) Fit the Hydrophobic Barrier, ensuring that the white
surface faces away from the sinter. Screw the Sample
Flow Housing on to the sensor and tighten with a
40mm A/F spanner.
(5) Set the sample flow rate to 1.5 ± 0.1 litres per minute,
unless otherwise directed in System installation
instructions.

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4.1 GENERAL
Maintenance consists of cleaning the sensor and accessories,
replacing the gasket and Hydrophobic Barrier and gassing
the sensor when testing the system.
CAUTIONS
1. The ECC cell contains a small quantity of acid. When
disposing of a sensor, it is necessary to comply with
the current waste disposal regulations, either local
or national ECC TYPE SENSORS SHOULD NEVER
BE DISPOSED OF BY PLACING IN A FIRE.
2. Exposure to gas concentrations above the design
range may result in the sensor needing re-calibrating
or checking.
3. Dismantling of a sensor or a sensor installation by
other than authorised engineers invalidates
certification.
In the event of exposure to contaminant or prolonged
exposure to high concentration of gas, the sensor should be
operated for 24 hours in a clean environment and then
recalibrated.
Note: If the sensor is found to be faulty, or cannot be
calibrated, the complete sensor must be discarded
and replaced.
4.2 CLEANING
The sensor and accessories may be cleaned using an
industrial grade of methanol. Whenever cleaning takes place,
a new Hydrophobic Barrier must be fitted and the following
precautions must be observed:
a. Isolate the power supply fromthe sensor by withdrawing
the associated Control Module from the installation.
b. Do not remove the sensor from the installation.
4. MAINTENANCE

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5.1 GENERAL
When testing and calibrating a gas detection system, the
sensors must be gassed in accordance with the practice
recommended for the particular installation. The sensor
should be calibrated with carbon monoxide using the
procedures detailed in Section 6.
5.2` CROSS INTERFERENCE FROM OTHER
GASES
Some gases, other than carbon monoxide, can produce an
output current. Those which may be encountered and typical
examples of their effect (if any) at 20ºC are as follows:
Gas Concentration Indication
in ppm H2S
Carbon Dioxide 5% Less than 1
Chlorine 20ppm Less than ±2
Ethylene 500ppm Less than 425
Hydrogen 1000ppm Less than 100
HydrogenSulphide 10ppm Less than 38
Methane 5%v/v Less than 5
Sulphur Dioxide 10ppm Less than 5
5.3 SENSOR LIFE
The expected life of the detector assembly is greater than 2
years. The guaranteed life is 12 months in use plus 6 months
storage, subject to storage at a stable temperature between
-10ºC to +20ºC. This guarantee will not apply to extended
use in harsh environments.
5. CALIBRATION

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5.4 CALIBRATION PROCEDURE
Notes: 1. Ensure that the sensor is not pressurised during
calibration by blockage of the exhaust (outlet of
the Flow Housing).
2. This procedure will produce an upscale output
signal which may activate alarms if fitted. Refer to
the Warnings in Section 2 Installation before
proceeding.
(1) Allow a minimum warm-up period of 1 hour after
applying power before carrying out this procedure.
(2) Insert the Digital Multimeter (DMM), set to read current,
in series with the 4 - 20mA line.
(3) Ensure that the sensor is in a gas-free atmosphere
then, if necessary, adjust the ZERO control for 4mA
on the DMM.
(4) Gas the sensor as instructed in Section 6 'Gassing the
Sensor'. After 3 minutes, set the SPAN control to
obtain a 20mA indication on the DMM for 50ppm CO.
(5) If procedures (3) and (4) cannot be achieved, adjust
the OFFSET control as follows:
a. Connect the DMM (set to read mV) between
TP2 and TP3 on pcb. (see Figure 7).
b. Adjust the ZERO control to obtain a reading of
0.000V ± 1mV on the DMM.
c. Disconnect the DMM.
d. Adjust the OFFSET control to obtain an output
(at the terminals) of 4mA.
e. Repeat steps (3) and (4). Remove the gas
adaptor and allow sufficient time for the test gas
to escape.
(6) Turn off the test gas and check the DMM indicates
4mA. If not, adjust the ZERO control for a DMM reading
of 4mA.
5. CALIBRATION

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6.1 EQUIPMENT REQUIRED
To test and calibrate the gas detection system the following
items are required:
a. A suitable Calibration Gas Test Kit and a bottle of the
appropriate test gas.
b. Where sensor accessories are not fitted, a Sample
Flow Housing will be required for accurate sensor
calibration.
Note: Purpose built gassing equipment is available on
request from Zellweger Analytics Limited.
6.2 CALIBRATION GASSING PROCEDURE
(1) Connect a suitable calibration gas test kit to the sensor
gassing nozzle, or to the permanently connected
pipeline where fitted.
CAUTION
Upward pressure on the gassing nozzle of Weather
Protection Housings, forces the nozzle against the
hydrophobic barrier. Do not rotate the nozzle when fitting
the pipeline as this may cause damage.
(2) Open the valve of the calibration gas test kit and set
the flow rate to 1.5 ± 0.1 litres per minute.
(3) Apply the gas to the sensor for a minimum period of 3
minutes.
(4) Set up the Control System as instructed in the Control
System manual.
(5) On completion, shut off the test gas and disconnect
the calibration gas test kit.
6. GASSING THE SENSOR