Sierra Monitor Corporation 2-Wire Series User manual

MODEL 4501-XX
2-Wire Series
TOXIC GAS SENSOR MODULE
APPLICABILITY & EFFECTIVITY
Effective for all Model 4501-XX Modules manufactured after September 1, 2006.
4501-03 FM Pending
4501-04 FM Pending
4501-05 FM Approved
4501-06 FM Pending
4501-08
4501-10
4501-12
4501-25
4501-26
Instruction Manual Part Number T13022
Rev. B

Model 4501-XX Toxic Gas Sensor Module
FM PERFORMANCE APPROVAL
ONLY THE FOLLOWING ITEMS, FUNCTIONS AND OPTIONS ARE FM*APPROVED
Model 4501-05 Hydrogen Sulfide Gas Sensor Module
Sensor Module
Model 4501-05 Sensor Module - Hydrogen Sulfide
Calibration Equipment
Model 1250-01 Gas Sensor Calibration Kit, Type A
Model 1260-05 Hydrogen Sulfide in N2, 25 ppm Gas Cylinder
Model 1260-45 Hydrogen Sulfide in N2, 10 ppm Gas Cylinder
Model 5358-01 Calibration Adapter
Notes:
1) Apparatus must be installed in accordance with National Electrical Code.
2) FM Comments.
*FM Approvals, a subsidiary of FM Global
Project# 3028099

Model 4501-XX Toxic Gas Sensor Module
TABLE OF CONTENTS
1. PRODUCT DESCRIPTION .............................................................................................................................1
1.1 GENERAL........................................................................................................................................................1
1.2 MOUNTING CONFIGURATION......................................................................................................................1
1.3 THEORY OF OPERATION..............................................................................................................................1
1.4 MECHANICAL .................................................................................................................................................2
1.5 INTERCONNECT WIRING..............................................................................................................................2
1.6 POWER REQUIREMENTS .............................................................................................................................2
2. CAUTIONS & WARNINGS .............................................................................................................................4
2.1 INTRODUCTION .............................................................................................................................................4
2.2 GAS SENSOR MODULES - GENERAL.........................................................................................................4
2.3 WIRING............................................................................................................................................................4
2.4 CALIBRATION FREQUENCY .........................................................................................................................4
3. QUICK START ................................................................................................................................................5
3.1 OVERVIEW......................................................................................................................................................5
3.2 WIRING............................................................................................................................................................5
3.3 MODULE INSTALLATION...............................................................................................................................5
3.4 TRANSMITTER INSTALLATION ....................................................................................................................5
3.5 START-UP & OPERATION .............................................................................................................................5
3.6 ZERO STABILIZATION ...................................................................................................................................5
4. INSTALLATION ..............................................................................................................................................6
4.1 SENSOR MODULE LOCATIONS ...................................................................................................................6
4.2 WIRING............................................................................................................................................................7
4.3 ENCLOSURE INSTALLATION........................................................................................................................7
4.4 TRANSMITTER AND SENSOR INSTALLATION ...........................................................................................8
5. OPERATION ...................................................................................................................................................9
5.1 INTRODUCTION .............................................................................................................................................9
5.2 DATA ENTRY KEYPAD ..................................................................................................................................9
5.3 MAIN MENU ..................................................................................................................................................10
5.4 SETUP SUB-MENU.......................................................................................................................................11
5.5 MAINTENANCE SUB-MENU ........................................................................................................................13
6. CALIBRATION..............................................................................................................................................14
6.1 CALIBRATION FREQUENCY .......................................................................................................................14
6.2 CALIBRATION PREPARATION....................................................................................................................14
6.3 CALIBRATION GAS DELIVERY METHODS.................................................................................................14
6.4 SENSOR EXPOSURE TO GAS ....................................................................................................................14
6.5 CALIBRATION SUB-MENU...........................................................................................................................15
7. SERVICE.......................................................................................................................................................16
7.1 SENSOR MODULE CONFIGURATION ........................................................................................................16
7.2 ENCLOSURE REPLACEMENT ....................................................................................................................16
7.3 TRANSMITTER REPLACEMENT .................................................................................................................17
7.4 SENSOR REPLACEMENT............................................................................................................................17
7.5 INSTALLATION INSPECTION ......................................................................................................................17
7.6 INSPECTION AND TROUBLESHOOTING GUIDE.......................................................................................18

Model 4501-XX Toxic Gas Sensor Module
8. APPENDICES ...............................................................................................................................................19
8.1 APPENDIX A: SPECIFICATIONS..................................................................................................................19
8.2 APPENDIX B: MODEL NUMBERS &PARTS LIST .......................................................................................22
8.3 APPENDIX C: LIMITED WARRANTY............................................................................................................24
8.4 APPENDIX D: 4501-25/26 GAS SENSOR MODULE ....................................................................................25
8.5 APPENDIX E: US FM APPROVAL ................................................................................................................29
8.6 APPENDIX F: CANADIAN FM APPROVAL...................................................................................................30
LIST OF FIGURES
1-1: MODEL 4501-XX-AL HYDROGEN SULFIDE GAS SENSOR MODULE …………………………………..…… 5
1-2: MODEL 4501-XX HYDROGEN SULFIDE GAS SENSOR MODULE – ORIENTATION OPTIONS ……..…... 5
4-1: TYPICAL MOUNTING OPTIONS ……………………..…………………………………………………………….. 8
4-2: 4-20 MA CONNECTION ………………………………..…………………………………………………………….. 9
4-3: CONNECTOR LOCATIONS ……………………………..…………………………………………………………..10
5-1: FACE PLATE WITH OPERATOR KEYPAD ……………..………………………………………………………...11
6-1: MODEL 5358-01 CALIBRATOR ADAPTOR ……………..……………………………………………………….. 15
7-1: MODULE COMPONENTS …………………………………..……………………………………………………… 17
8-1: MODULE COMPONENTS ……………………………………..…………………………………………………….26
8-2: SENSOR ASSEMBLY – EXPLODED VIEW …………………..………………………………………………….. 28
8-3: MODEL 4501-25-AL & 4501-26-AL………………………………..………………………………………………... 29
8-4: MODEL 4501-25-SS & 4501-26-SS...……………………………..………………………………………………... 29
LIST OF TABLES
5-1: MASTER MENU ……………………………………………………..……………………………………………….. 12
5-2: KEY OPERATIONAL DISPLAY …………………………………….….…………………………………………….12
5-3: SET-UP CONFIGURATION …………………………………………..…………………………………………...... 13
5-4: MAINTENANCE SUB MENU ………………………………………..…………………………………………….... 14
6-1: CALIBRATION ……………………………………………………………..…………………………………………. 16

Model 4501-XX Toxic Gas Sensor Module
Page 1 of 33
1. PRODUCT DESCRIPTION
1.1 GENERAL
The Model 4501-XX Toxic Gas Sensor Module is a 2-wire transmitter with 4-20 mA output and it offers a broad
array of features including:
2-wire loop powered
180 day calibration interval
Selectable ranges (if appropriate for gas type)
Non-intrusive one-person calibration
Integral LCD 2-line, 20-character display
Stainless steel enclosure and sensor housing
4-20 mA output
Long sensor life
Rotatable faceplate enables multi-directional conduit
installation.
The 4501-XX is designed and approved for installation and
operation in hazardous locations.
Members of the 4501-XX Two-Wire Toxic Gas family include:
▪4501-03 Oxygen Gas Sensor Module
▪4501-04 Carbon Monoxide Gas Sensor Module
▪4501-05 Hydrogen Sulfide Gas Sensor Module
▪4501-06 Chlorine Gas Sensor Module
▪4501-08 Chlorine Dioxide Gas Sensor Module
▪4501-10 Sulfur Dioxide Gas Sensor Module
▪4501-12 Nitrogen Dioxide Gas Sensor Module
▪4501-25 Ammonia Gas Sensor Module
▪4501-26 Hydrogen Fluoride Gas Sensor Module
1.2 MOUNTING CONFIGURATION
Various module mounting configurations can be implemented without special fixtures. Where applicable,
these options are factory configured prior to shipment. Mounting configuration can be selected by the installer
or field technician and are fully described in this manual. Sensor must always be oriented downward.
1.3 THEORY OF OPERATION
Electrochemical sensors are fuel cell-like devices consisting of an anode, cathode, and electrolyte. The
components of the cell are selected so a subject gas, allowed to diffuse into the cell, will cause a chemical
reaction and generate a current. The cells are diffusion limited so the rate the gas enters the cell is solely
dependent on the gas concentration. The current generated is proportional to the rate of consumption of the
subject gas in the cell.

Model 4501-XX Toxic Gas Sensor Module
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Sierra Monitor electrochemical sensors provide improved reliability by allowing the gas to diffuse into the
sensor through a capillary port, rather than diffusing through membranes. The result is an extremely stable
sensor with very low temperature and pressure coefficients and the capability to monitor gas as ppm.
1.4 MECHANICAL
The sensor module is comprised of the following three primary components:
1.4.1 ENCLOSURE
Explosion proof, rain-tight aluminum or stainless steel electrical housing with three ¾” FNPT conduit hubs.
The enclosure cover has a viewing window. The 3 conduit hubs combined with the rotatable faceplate
enable the user to mount the module in a variety of configurations. See Figure 1-2 for details.
1.4.2 TRANSMITTER ELECTRONICS
Electronic Assembly consisting of one printed circuit board assembly mounted under a cover plate. Wiring
connections for power and signal interface are located on the back side of the display.
1.4.3 SENSOR ASSEMBLY
The sensor assembly includes a stainless steel, explosion proof, housing containing the gas sensor and a
wiring harness for connection to the transmitter. The sensor assembly threads into one hub of the
enclosure. The exposed end of the sensor assembly is threaded to allow connection of a rain-shield or
calibration gas delivery fitting.
1.5 INTERCONNECT WIRING
Not supplied with the sensor module, but necessary to the installation and operation is the two conductor
wiring shielded which connects the module to its power source and controller. Before this wiring is installed it
is important to read and understand the control system installation instructions to determine wiring
requirements and alternatives.
1.6 POWER REQUIREMENTS
The 4501-XX module operates on DC power between 14 VDC and 30 VDC. The DC power must be supplied
by the loop controller.

Model 4501-XX Toxic Gas Sensor Module
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Figure 1-2
Model 4501-XX Hydrogen Sulfide Gas Sensor Module– Orientation Options
Figure 1-1
Model 4501-05-AL or SS Hydrogen Sulfide Gas Sensor Module

Model 4501-XX Toxic Gas Sensor Module
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2. CAUTIONS & WARNINGS
2.1 INTRODUCTION
Although the 4501-XX Gas Sensor Module is designed and constructed for installation and operation in
industrial applications including hostile environments, caution should be taken to insure that the installation is
made in compliance with this instruction manual and that certain procedures and conditions are avoided. This
chapter discusses the necessary cautions. Read the entire chapter prior to installation of the equipment.
2.2 GAS SENSOR MODULES - GENERAL
Avoid installing sensor modules where they will be unnecessarily exposed to wind, dust, water (i.e. direct hose
down), shock, or vibration. Observe temperature range limitations.
Sensors may be adversely affected by prolonged exposure to certain materials. Loss of sensitivity, or
corrosion, may be gradual if such materials are present in low concentrations. These materials include:
Halides (compounds containing chlorine, fluorine, bromine, iodine), acid vapors, caustic liquids or mists.
Care has been taken by the manufacturer to ship modules in protective packaging to avoid contamination prior
to installation. It is recommended that the modules remain protected during installation and that the covering
be removed immediately prior to system start-up.
During normal use the O2, CO, H2S, SO2and NO2sensors are protected from dirt and oil contamination by a
sintered metal cover. If this cover becomes clogged, the response of the sensor will be reduced. Protect the
sensor from contamination by careful placement, or by use of rain shields and dust shields.
Sensor modules must not be painted. Paint may contain compounds which will contaminate the sensor. Paint
will cause clogging of the sintered metal cover and will cause difficulties during attachment of the calibration
head or other maintenance activity. It is recommended that the module be tagged "DO NOT PAINT".
2.3 WIRING
The manufacturer recommends that extra caution be taken where the installation is near any sources of
electromagnetic or radio frequency interference. Precautions include:
Avoid running sensor module cable close to high power cables, radio transmission lines, or cables
subject to pulses of high current.
Avoid running cables near large electric motors or generators.
Analog devices require shielded cable.
In conduit installations and cable applications the shield should be connected to instrument ground.
All splices must be via either a termination hardware system or soldered. Improperly spliced cable can
result in corrosion, resistance changes and system errors.
NOTE
Installation and wiring must be in accordance with the National Electrical Code.
Voltage AC conductors are not to be run in the same conduit as voltage DC
conductors.
2.4 CALIBRATION FREQUENCY
The 4501-XX calibration frequency is six months (180 days). However, prudent gas detector maintenance
practices normally suggest a simple recalibration following incidences of exposure to high levels of gas that
would lead to alarm activation within any system utilizing the output of the gas sensor module.

Model 4501-XX Toxic Gas Sensor Module
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3. QUICK START
3.1 OVERVIEW
The gas sensor module has been supplied factory calibrated and ready for immediate installation and
operation. An installer familiar with installation and operation of gas detection products can use this section to
begin immediate use of the module.
3.2 WIRING
Provide two conductor twisted shielded wiring from the power supply/control device to the sensor module
location. Use wire that is 18 AWG or larger.
3.3 MODULE INSTALLATION
The 4501-XX can be mounted in a variety of configurations supported by the conduit. See figure 1-2 to
determine which configuration is best for your specific application. The default configuration enables the
modules to be put in line with other modules with the sensor element below the transmitter. To change the
configuration simply remove the transmitter and rotate to the appropriate configuration and remount the
standoffs and transmitter.
The module is designed to be installed on a ¾” conduit. Two important warnings:
The installation must meet any hazardous environment codes for electrical equipment.
The sensor module enclosure mounting must be spaced far enough from any vertical surface
to allow removal and replacement of the sensor assembly which is threaded into one ¾”
conduit entry.
Sensor housing must be oriented vertically pointing downward.
3.4 TRANSMITTER INSTALLATION
To install the transmitter printed circuit assembly into the housing, carefully turn the faceplate so that the
printing is in the correct horizontal position for the mounting configuration and slide the assembly over the two
stand-offs in the enclosure.
Hand tighten the two captive panel thumb screws into the stand-offs. Replace the enclosure cover prior to
providing power to the transmitter.
If the transmitter is installed in a classified hazardous area, replace the threaded cover prior to
providing power.
3.5 START-UP & OPERATION
To begin operation of the sensor module activate the instrument loop with 14-30 VDC. Each time the sensor
module is powered up it will perform a warm-up for approximately 1.0 minutes (60 seconds). During this time
the display will read “Starting”. The loop output will be held at 4 mA.
NOTE: If the sensor is uncalibrated, the startup display will state “UNCALIB” instead of “STARTING”
NOTE: The 4501-06, 4501-08, 4501-25 and 4501-26 require 300 seconds warm-up period
After the warm-up period has expired, the display will indicate the gas concentration. Also, the instrument loop
will be released to output current in the range of 4 to 20 mA. The actual current is linear with the gas
concentration and depends on the selected range. For instance, when the range of 0 to 50 PPM has been
selected, a current of 4 mA corresponds to 0 PPM and a current of 20 mA corresponds to 50 PPM.
3.6 ZERO STABILIZATION
All electrochemical sensors require at least 30 minutes on power prior to calibration. This allows the electrode
potentials to equilibrate, resulting in a stable zero signal level.

Model 4501-XX Toxic Gas Sensor Module
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4. INSTALLATION
4.1 SENSOR MODULE LOCATIONS
The gas sensor module utilizes a diffusion type sensor which
should be located close to either the expected source or
destination of the gas hazard. If the gas is heavier than air, the
sensor module should be installed within 24 inches of the ground
or floor. If it is lighter than air, move it above 6’.
After optimum locations are determined based on the above
recommendations, consideration should be given to placing the
sensor modules in locations which are accessible for calibration
service. Slight adjustments to the location of the sensor module
may have little impact on effectiveness but major effect on
accessibility.
Modules should be placed in areas accessible for
calibration.
The cover should face out from the wall for easy access.
Sensors should be pointed down and the conduit should
include an inverse trap to reduce moisture (condensation)
from accumulating in the electronics enclosure.
Model Gas Specific Gravity
N/A Air 1.00
4501-04 CO 0.97
4501-05 H2S 1.19
4501-06 Cl22.49
4501-08 ClO23.09
4501-10 SO22.26
4501-12 NO21.59
4501-25 NH30.60
4501-26 HF 1.86
Table 4-1
Specific Gravities
Figure 4-1
Typical Mounting Options

Model 4501-XX Toxic Gas Sensor Module
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Figure 4-2
4-20 mA Connection
4.2 WIRING
Wire should be 18 AWG minimum at a maximum distance is 5,000 feet. Install conduit as required by
local code or construction specifications.
See figure 4-2 for typical 2 terminal and 4 terminal connections.
4.3 ENCLOSURE INSTALLATION
To protect the transmitter and sensor assembly they should be removed from the enclosure and preserved
until final installation and wiring termination.
Prior to installation and wiring:
1. Remove the transmitter from the module housing by:
Unscrew the two captive panel screws on the faceplate.
Lift the transmitter out of the enclosure.
Unplug the sensor cable from transmitter connector J1.
Remove the sensor assembly from the enclosure hub.
2. Install the module enclosure onto the end of the supply conduit and/or bolt into position as required.
NOTE
When enclosure earth grounding is required for the installation a grounding lug is located in
the base of the enclosure. Install the earth ground under the green ground screw.

Model 4501-XX Toxic Gas Sensor Module
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4.4 TRANSMITTER AND SENSOR INSTALLATION
When all pre-wiring is complete:
1. Install sensor assembly in the open hub on the module enclosure. The sensor assembly thread
must be fully seated into the hub and tightened to maintain explosion proof assembly.
2. Connect the sensor assembly cable to transmitter connector J1. (Figure 4-3)
3. Connect the loop wires (Loop + and Loop -) to transmitter connector P1 4-20 mA + and –
(Figure 4-3).
NOTE
Conductor P1 is removable
4. Carefully return the transmitter to the enclosure installing it over the two standoffs. Finger tighten
the retaining screws into the standoffs.
Figure 4-3
Connector Locations
Loop Power
Sensor
Connector

Model 4501-XX Toxic Gas Sensor Module
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Figure 5-1
Face Plate with Operator Keypad
5. OPERATION
5.1 INTRODUCTION
The 4501-XX Toxic Gas Sensor Module utilizes a visual menu system operated by means of a magnet with
the cover in place. A magnet stick is supplied for this purpose. Access the menu system to calibrate the
sensor module, and for maintenance and diagnostic procedures.
The following adjustments can be made to the sensor module:
Range adjustments (see section 5.4)
4mA and 20mA calibration adjustments (see section 5.4)
Span adjustment (see section 6.3)
5.2 DATA ENTRY KEYPAD
The module menu system is operated by means of directing the magnet stick toward each of four independent
hall-effect magnetic switches. Each switch functions as if it is a manually activated panel key. The keys are
located under the faceplate above and below the LCD and are labeled M , E , and as shown in
Figure 5-1.
Key : MODE
Key ENTER
Key : UP (+)
Key : DOWN (-)

Model 4501-XX Toxic Gas Sensor Module
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Table 5-2
Key Operational Display
5.3 MAIN MENU
Function Display Description Reference
ME

ME

ME

ME

ME

ME

ME

ME

4501-XX
Starting
Third screen at start-up, will remain for 60 seconds
(4501-05)
4501-XX
Version Second screen at start-up, Version (e.g. V300aA)
H2S
XXX.PPM Default Display (example 4501-05)
Key
Mode Switch [M]
Enter Switch [E]
Up Switch [▲] Previous Menu
Down Switch [▼] Next Menu
4501-XX
CAL 180
First screen at power-up, Model and days to
calibration
Mode H2S
CALIB: Mode Function: Calibration (example 4501-05) Table 6-1
Down H2S
MAINT: Mode Function: Maintenance (example 4501-05) Table 5-5
Down H2S
SETUP: Mode Function: Setup (example 4501-05) Table 5-4
Table 5-1
Master Menu
Down H2S
Exit-? Exit Mode (example 4501-05)
Table 5-2 defines the key operational displays on the operator interface.
Display Description
- H2S -
STARTING Warm-up at start-up (example 4501-05)
SENSOR
FAIL Sensor failure
NO
SENSOR Sensor not found or plugged in
C.## PPM Calibration Mode
F.## PPM Failure detected, sensor is attempting recovery
XXX
DONE Finished with step

Model 4501-XX Toxic Gas Sensor Module
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5.4 SETUP SUB-MENU
The sensor module set-points menu is used to initially set-up the range and 4-20 mA calibration.
Range: Once the Set-up menu is selected, press key [▼] twice and press [E] to activate the Range Set-
up menu. Use the [▲] or [▼] keys to select Range menu and press [E]. When “Range” is selected menu
provides any choices of ranges available for the gas type selected. Use the [▲] or [▼] keys to select the
desired range. If the “User” range is selected, use the [▲] or [▼] keys to adjust the high end of the range
desired. See specifications below for optional ranges.
4-20mA: Once the Set-up menu is selected, press key [▼] three times and press [E] to activate the 4-
20mA Set-up menu. Use the [▲] or [▼] keys to select Calib menu and press [E]. The “Calib” section of
the menu allows the user to calibrate the 4 mA and 20 mA outputs. To calibrate the 4 mA and 20 mA
outputs it is necessary to have an amp meter connected to the 4501-XX and upon selecting the 4 mA
output calibration then the [▲] or [▼] keys can be used to adjust the 4 mA reading on the amp meter until it
reads 4 mA. Similar steps can then be performed for the 20 mA output.
Factory Range Set-up
Model Range Other Available
4501-03 5-25% 0-25%
4501-04 0-500 PPM Variable
4501-05 0-100 PPM Variable
4501-06 0-10 PPM None
4501-08 0-3 PPM None
4501-10 0-100 PPM Variable
4501-12 0-20 PPM None
4501-25 0-100 PPM Variable
4501-26 0-10 PPM None

Model 4501-XX Toxic Gas Sensor Module
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Function Display Description Reference
ME

ME

M
E

ME

ME

ME

ME

ME

ME

ME

ME

ME
 Enter H2S
ACK Momentary Acknowledge of new Set Point
Enter H2S
4mA Selects 4 mA
Gas Range Adjustment Example
Enter Range S.P. Function - Range Adjust
Enter H2S
*100 PPM Select [E] to select or or to select another and press [E]
Down H2S
10 PPM Press [E] if selecting 0-10 PPM range
Down H2S
USER Press [E] if selecting User adjustable range
Table 5-3 Set-Up Configuration
Down H2S
SETUP:
Mode H2S
CALIB:
Key
H2S
XX PPM Default Display (example 4501-05)
Enter H2S
100 PPM Select [E] to select or or to select another and press [E]
4-20 mA Adjustment Example
Enter H2S
Calib S.P. Function - Calib Adjust
Down H2S
4-20mA S.P Function 4-20 mA Calibrator
Enter H2S
Out: 4mA Use or keys to select 4 mA or 20mA

Model 4501-XX Toxic Gas Sensor Module
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5.5 MAINTENANCE SUB-MENU
The maintenance menu enables the operator to view sensor and software versions. Sierra Monitor technical
support has access to other values as needed. The maintenance menu operation is described in Table 5-4.
Function Display Description Reference
ME

ME

ME

ME

ME

ME

H2S
VX.XX Version number of firmware
Enter H2S:
CCC001 Configuration Version
Table 5-4
Maintenance Sub Menu
Enter H2S
CALIB Go to previous maintenance menu item
Down H2S
SETUP:
Enter
Key
Mode H2S
XXX PPM Default Display(example 4501-05)
Down H2S
MAINT:

Model 4501-XX Toxic Gas Sensor Module
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6. CALIBRATION
6.1 CALIBRATION FREQUENCY
The sensor module must be calibrated every 180 days at a minimum. Periodic functional tests are advisable
for critical applications and hostile environments.
The sensor module microprocessor software includes high-level self checking algorithms which provide
continuous sensor diagnostic and self adjustment.
6.2 CALIBRATION PREPARATION
Calibration of the sensor is accomplished by simple menu based steps and application of span gas.
NOTE
If an error is made during any stage of the calibration process, hold the magnet stick at the
[M] for 10 seconds. A scrolling display will indicate “calibration aborted” and the sensor
module will exit the calibration activity and return to normal operating mode. The calibration
procedure can then be restarted.
Calibration must be performed only when the area is known to be clear of the gas of interest. When in doubt,
use a portable instrument to confirm that there is no background.
For compliance with Factory Mutual (FM) Approvals, the Sierra Monitor Model 1250-01, 1260 -05 and 1260-45
are the FM Approved calibration gas delivery devices. Use the Model 5358-01 Calibration Adapter delivery
fitting.
NOTE: Refer to Appendix D for information on use of permeation tube for 4501-25 calibration.
6.3 CALIBRATION GAS DELIVERY METHODS
Calibration gas can be delivered to the sensors via the Model 5358-01:
Calibration Adapter (Figure 6-1) - used with portable calibrators.
CALIBRATION PROCEDURE
The Calibration Menu is described on Table 6-1:
The procedure requires that the menu “keys” be activated using the magnet stick.
Each key press steps through the process of setting the zero value for clean air
and then setting the span value.
At each of these steps, apply calibration gas of the value corresponding to
the setting accepted on the sensor module display.
6.4 SENSOR EXPOSURE TO GAS
Calibration gas must be delivered to the sensor using the flow rate and
duration listed in below:
Model Calibration Gas Flow Period
4501-03 Air 300 cc of Zero Air or exposure to Ambient Air (3 minutes)
4501-04 Carbon Monoxide 300 cc/min Until Stable (minimum 3 minutes)
4501-05 Hydrogen Sulfide 300 cc/min Until Stable (minimum 3 minutes)
4501-06 Chlorine 300 cc/min Until Stable (minimum 3 minutes)
4501-08* Chlorine 300 cc/min Until Stable (minimum 3 minutes)
4501-10 Sulfur Dioxide 300 cc/min Until Stable (minimum 3 minutes)
4501-12 Nitrogen Dioxide 300 cc/min Until Stable (minimum 3 minutes)
4501-25 Ammonia See Appendix D
4501-26** Chlorine 500 cc/min Until Stable (minimum 6 minutes)
* Note: Use 10 PPM Cl2to calibrate, equivalent reading = 3.0 PPM ClO2
** Note: Use 5 PPM Cl2to calibrate equivalent reading = 8.0 PPM HF
Figure 6-1
Model 5358-01
Calibration Adapter
Sample Gas In

Model 4501-XX Toxic Gas Sensor Module
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6.5 CALIBRATION SUB-MENU
* 4501-03 –
Oxygen Calibration: If area is known to be safe with adequate air flow, you may use the surrounding air as the calibration gas.
If Oxygen levels are unknown, it is recommended to use a Zero Air gas standard.
When calibrating an Oxygen module, there is no zero gas process in the calibration procedure. Only span adjustments can be
made. Normal ambient Air = 20.9% Oxygen.
Begin calibration procedure using the magnet on the Mode key until CALIB is displayed.
Enter to begin procedure. Select cal gas value (20.9), Enter to confirm.
Apply span gas for 3 minutes or use surrounding air if acceptable.
Select Enter when done, and procedure is complete.
NOTE
The Analog output values to be transmitted during the calibration procedure are selected in
the maintenance configuration. Normal 20.9% value provides 17.3 mA.
Function Display Description Reference
ME

ME

ME

ME

ME

ME

ME

ME

ME

ME

ME

Sub-Routines
XXXPPM Default Display
Operation: Confirm area clear of gas, or apply zero air to
sensor.
H2S
10PPM-SP Banner: Select span, enter <E> when done*
Enter H2S
ACK Zero gas setting acknowledged
H2S
CXXX PPM Banner: Apply span gas, then enter <E> to calibrate gas sensor
H2S
CXXX PPM Operation: Apply calbrationgas.
Enter
Sub A
Sub A
Sub B
H2S
10PPM-SP Banner: Select span, enter <E> when done
Down H2S
25PPM-SP Operation: Change Span Gas Value to25PPM
H2S
WAIT-300
Operation: Five minute time out before sensor is returned to
service.
Down H2S
Adj-SPAN Operation: User adjustable value
Enter H2S
25PPM-SP Operation: Ready for user adjustment
Mode Function - Calibrate
Enter H2S
Cal Zero Banner: Apply zero gas, enter <E> when done
Mode H2S
CAL IB:--
Key
Table 6-1
Calibration
Banner: Calibration Aborted
Mode
H2S
XXXPPM Default Display
H2S
CXXXPPM
Operation: As gas is applied the reading will increase - wait 3
minutes
Enter H2S
CAL-OK Calibration Passed - now remove gas
H2S
WAIT-300
Operation: Five minute time out before sensor is returned to
service.
Enter H2S
CAL -FAI L
Operation: No calibration gas applied, or sensor did not respond
correctly.
(Any) Operation: Hold magnet over Mode Switch for ten senconds to
abort calibration Sub C
Enter H2S
C 25PPM
Banner: Apply 25PPM gas, then enter <E> to calibrate gas
sensor Sub B
H2S
C 25PPM Operation: Apply calbrationgas.

Model 4501-XX Toxic Gas Sensor Module
Page 16 of 33
Figure 7-1
Module Components
7. SERVICE
7.1 SENSOR MODULE CONFIGURATION
The gas sensor module is comprised of the following sub-assemblies (Figure 7-1):
4501-XX Gas Sensor Module
SPL27077 Stainless Steel Enclosure (SPL 27085 for Aluminum Enclosure)
SPM27071 Transmitter Assembly
XXXXXXX Sensor Assembly (see Appendix B)
XXXXXXX Sensor (see Appendix B)
There are no field serviceable components below the sub assembly level.
NOTE
Area must be determined to be non-hazardous before opening enclosure.
7.2 ENCLOSURE REPLACEMENT
The enclosure should be replaced if the cover threads or conduit threads have been damaged, or if the
enclosure has been damaged sufficiently that it no longer meets the required NEMA classification.
To replace the enclosure follow the transmitter and sensor assembly removal instructions, remove the
damaged enclosure from its conduit, install a new enclosure and continue the transmitter and sensor assembly
replacement instructions.