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