Sierra Monitor 4501-XX Electrochemical 2-Wire Toxic Gas Sensor Owner's manual

Brand: Sierra Monitor

Model: 4501-XX Electrochemical 2-Wire Toxic Gas Sensor

Category: Carbon monoxide (CO) detectors

Type: Owner's manual

This manual is also suitable for

SMC 4501-XX Toxic Gas Detector

Manual # T13022

Document Revision: C2

Model 4501-XX

2-Wire Series

Toxic Gas Sensor Module

APPLICABILITY & EFFECTIVITY

Effective for all Model 4501-XX Modules manufactured after September 2018.

4501-03 4501-04 4501-05 (FM Approved) 4501-06 4501-08

4501-10 4501-12 4501-25 4501-26

Model 4501-XX Toxic Gas Sensor Module

Contact Information

Manual Number: T13022

This manual contains intellectual property that was developed by Sierra Monitor Corporation and is

protected by the copyright laws of the United States, international copyright treaties, and all other

applicable national laws. This manual contains information regarding technology that is protected under

one or more issued or pending United States and foreign patents.

Sierra Monitor and Sentry IT are trademarks of Sierra Monitor Corporation. All other trademarks are the

property of their respective owners.

This manual is licensed to users of Sierra Monitor products and may be copied, in whole or in part.

The offices of Sierra Monitor are located at:

Sierra Monitor Corporation

1991 Tarob Court

Milpitas, CA 95035

USA

Customer Service:

Telephone: (408) 964-4443

Fax: (408) 262-9042

Toll-Free: (800) 727-4377

Email: support@sierramonitor.com

Website: www.sierramonitor.com

Model 4501-XX Toxic Gas Sensor Module

FM Information

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

 Specific Conditions of Use:

- Consult the original manufacturer for information on the dimensions of the flameproof

joints.

- Appropriate certified cable glands for direct entry must be used.

  Model 4501-XX Toxic Gas Sensor Module 
Table of Contents 
TABLE OF CONTENTS 
TABLE OF CONTENTS .............................................................................................................................................4 
LIST OF FIGURES .....................................................................................................................................................6 
PRODUCT DESCRIPTION .................................................................................................................................7 
1  General .........................................................................................................................................................7 
2  Mounting Configuration ................................................................................................................................7 
3  Theory of Operation .....................................................................................................................................8 
4  Mechanical ...................................................................................................................................................8 
4.1  Enclosure ..............................................................................................................................................8 
4.2  Transmitter Electronics ...................................................................................................................... 10 
4.3  Sensor Assembly ............................................................................................................................... 10 
5  Interconnected Wiring ............................................................................................................................... 10 
6  Power Requirements ................................................................................................................................. 10 
CAUTIONS AND WARNINGS ......................................................................................................................... 11 
1  Introduction ................................................................................................................................................ 11 
2  Gas Sensor Modules – General ................................................................................................................ 11 
3  Wiring ........................................................................................................................................................ 11 
4  Calibration Frequency ............................................................................................................................... 11 
QUICK START ................................................................................................................................................. 12 
1  Overview ................................................................................................................................................... 12 
2  Wiring ........................................................................................................................................................ 12 
3  Module Installation .................................................................................................................................... 12 
4  Transmitter Installation .............................................................................................................................. 12 
5  Start-Up & Operation ................................................................................................................................. 12 
6  Zero Stabilization ...................................................................................................................................... 12 
INSTALLATION ............................................................................................................................................... 13 
1  Sensor Module Locations .......................................................................................................................... 13 
2  Wiring ........................................................................................................................................................ 14 
3  Enclosure Installation ................................................................................................................................ 14 
4  Transmitter and Sensor Installation .......................................................................................................... 15 
OPERATION .................................................................................................................................................... 16 
1  Introduction ................................................................................................................................................ 16 
2  Data Entry Keypad .................................................................................................................................... 16 
3  Main Menu ................................................................................................................................................. 17 
4  Setup Sub-Menu ....................................................................................................................................... 18 
5  Maintenance Sub-Menu ............................................................................................................................ 19 
CALIBRATION ................................................................................................................................................. 20 
1  Calibration Frequency ............................................................................................................................... 20 
2  Calibration Preparation ............................................................................................................................. 20 
3  Calibration Gas Delivery Methods............................................................................................................. 20 
4  Sensor Exposure to Gas ........................................................................................................................... 21 
5  Calibration Sub-Menu ............................................................................................................................... 21 
APPENDIX A. SERVICE ......................................................................................................................................... 23 
Appendix A.1. Sensor Module Configuration ....................................................................................................... 23 
Appendix A.2. Enclosure Replacement ............................................................................................................... 23 
Appendix A.3. Transmitter Replacement ............................................................................................................. 24 
Appendix A.4. Sensor Replacement .................................................................................................................... 24 
Appendix A.5. Installation Inspection ................................................................................................................... 24 
Appendix A.5.1. Controller Installation ............................................................................................................. 24 
Appendix A.5.2. Cabling Installation ................................................................................................................ 24 
Appendix A.5.3. Sensor Module Installation .................................................................................................... 25 
Appendix A.5.4. Moisture Traps And Rainshields ............................................................................................ 25 

  Model 4501-XX Toxic Gas Sensor Module 
Table of Contents 
Appendix A.5.5. Standard Voltages ................................................................................................................. 25 
Appendix A.6. Inspection and Troubleshooting Guide......................................................................................... 25 
Appendix A.6.1. Module Does Not Respond to Gas ........................................................................................ 25 
Appendix A.6.2. The Module Displays “Starting” for More Than 1 Hour .......................................................... 25 
Appendix A.6.3. The Module Does Not Display The Correct PPM .................................................................. 25 
Appendix A.6.4. The Display Shows ‘F’ OR “NO SENSOR” ............................................................................ 25 
Appendix A.6.5. The Display Shows ‘C’ ........................................................................................................... 25 
APPENDIX B. SPECIFICATIONS .......................................................................................................................... 26 
APPENDIX C. MODEL NUMBERS & PARTS LIST ............................................................................................... 29 
APPENDIX D. LIMITED WARRENTY .................................................................................................................... 30 
APPENDIX E. 4501-25 & 4501-26 GAS SENSOR MODULE ................................................................................ 31 
APPENDIX F. US FM APPROVAL ......................................................................................................................... 35 
APPENDIX G. APPENDIX F. CANADIAN FM APPROVAL .................................................................................. 37 
APPENDIX H. ATEX CERTIFICATE ...................................................................................................................... 40 
APPENDIX I. PIPE MOUNTING FOR 4501-XX ALUMINUM ................................................................................. 41 
 
 
 

  Model 4501-XX Toxic Gas Sensor Module 
List of Figures 
LIST OF FIGURES 
Figure 1: Model 4501-XX Hydrogen Sulfide Gas Sensor Module – Mounting Options .............................................8 
Figure 2: Model 4501-05-S1/S2/A2 Toxic Gas Sensor – Stainless Steel/Aluminum Enclosure, Dimensions ...........9 
Figure 3: Model 4501-05-A1 Toxic Gas Sensor – Cast Aluminum Enclosure, Dimensions ......................................9 
Figure 4: Specific Gravities ...................................................................................................................................... 13 
Figure 5: Typical Mounting Options ......................................................................................................................... 13 
Figure 6: 4-20 mA Connection ................................................................................................................................. 14 
Figure 7: Connector Locations ................................................................................................................................ 15 
Figure 8: Face Plate with Operator Keypad ............................................................................................................ 16 
Figure 9: Master Menu............................................................................................................................................. 17 
Figure 10: Operation Display Values ....................................................................................................................... 17 
Figure 11: Set-Up Configuration .............................................................................................................................. 18 
Figure 12: Maintenance Sub-Menu ......................................................................................................................... 19 
Figure 13: Model 5358-01 Calibration Adapter ....................................................................................................... 20 
Figure 14: Calibration Sub-Menu ............................................................................................................................. 21 
Figure 15: Module Components .............................................................................................................................. 23 
Figure 16: Electrolyte Replacement ........................................................................................................................ 31 
Figure 17: Sensor Assembly – Exploded View ....................................................................................................... 33 
Figure 18: Model 4501-25-A1 and Model 4501-26-A1 ............................................................................................ 34 
Figure 19: Model 4501-25-S1 and Model 4501-26-S1 ............................................................................................ 34 
Figure 20: Model 4501-XX-A1 Aluminum Enclosure Pipe Mount ........................................................................... 41 
Figure 21: Pipe Mount Bracket for 4501-XX-A1 Aluminum Enclosure .................................................................... 41 
 

Model 4501-XX Toxic Gas Sensor Module

Page 7 of 41

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 multidirectional 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 Dioxide 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.

Model 4501-XX Toxic Gas Sensor Module

Page 8 of 41

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.

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 (Figure 2 & Figure 3) 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 (Figure 1).

NOTE: Module installation must be such that it is mounted vertically with sensor pointing downward.

Figure 1: Model 4501-XX Hydrogen Sulfide Gas Sensor Module – Mounting Options

Model 4501-XX Toxic Gas Sensor Module

Page 9 of 41

Figure 2: Model 4501-05-S1/S2/A2 Toxic Gas Sensor – Stainless Steel/Aluminum Enclosure, Dimensions

Figure 3: Model 4501-05-A1 Toxic Gas Sensor – Cast Aluminum Enclosure, Dimensions

Model 4501-XX Toxic Gas Sensor Module

Page 10 of 41

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 Interconnected 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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2 CAUTIONS AND 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 O

, CO, H

S, SO

, and NO

sensors 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

Page 12 of 41

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 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. Three 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.

NOTE: For transmitters installed in classified hazardous areas, 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

Page 13 of 41

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

0.97

4501-05

1.19

4501-06

2.49

4501-08

ClO

3.09

4501-10

2.26

4501-12

1.59

4501-25

0.60

4501-26

1.86

Figure 4: Specific Gravities

Figure 5: Typical Mounting Options

Model 4501-XX Toxic Gas Sensor Module

Page 14 of 41

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 6 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.

a. Unscrew the two captive panel screws on the faceplate.

b. Lift the transmitter out of the enclosure.

c. Unplug the sensor cable from transmitter connector J1.

d. 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.

Figure 6: 4-20 mA Connection

Model 4501-XX Toxic Gas Sensor Module

Page 15 of 41

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 7)

3. Connect the loop wires (Loop + and Loop -) to transmitter connector P1 4-20 mA + and – (Figure 7).

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.

Loop Power

Sensor

Connector

Figure 7: Connector Locations

Model 4501-XX Toxic Gas Sensor Module

Page 16 of 41

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 (Section 5.4)

⧫ 4mA and 20mA calibration adjustments (Section 5.4)

⧫ Span adjustment (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 8.

Figure 8: Face Plate with Operator Keypad

Model 4501-XX Toxic Gas Sensor Module

Page 17 of 41

5.3 Main Menu

Key

Function

Display

Description

Reference

Mode

Switch [M]

▲

▼

Enter

Switch [E]

▲

▼

Switch [▲] Previous Menu

▲

▼

Down

Switch [▼] Next Menu

▲

▼

CAL 180

First screen at power up: Model No. and days to calibration

Version

Second screen at power up: Version No. (e.g. V300aA)

STARTING

Third screen at start up, will remain for 60 seconds

XXX PPM

Normal condition - default display

Mode

CALIB:

Mode Function - Calibrate

Figure 14

▲

▼

Down

SETUP:

Mode Function - Set up alarms, relays, etc.

Figure 11

▲

▼

Down

MAINT:

Mode Function - Maintenance

Figure 12

▲

▼

Down

EXIT-?

Exit Mode

▲

▼

Figure 9: Master Menu

The table below defines the key operational displays on the operator interface.

Display

Description

- H2S –

STARTING

Warm-up at start-up (example from 4501-05)

SENSOR

FAIL

Sensor failure

SENSOR

Sensor not found or plugged in

C.## PPM

Calibration Mode

F.## PPM

Failure detected, sensor is attempting recovery

XXX

DONE

Finished with step

Figure 10: Operation Display Values

Model 4501-XX Toxic Gas Sensor Module

Page 18 of 41

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.

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

• 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.

Key

Function

Display

Description

Reference

XX PPM

Default Display (example 4501-05)

Mode

CALIB:

▲

▼

Down

SETUP:

▲

▼

Gas Range Adjustment Example

Enter

Range

S.P. Function - Range Adjust

▲

▼

Enter

*100 PPM

Select [E] to select or ▲ or ▼ to select another and press [E]

▲

▼

Down

10 PPM

Press [E] if selecting 0-10 PPM range

▲

▼

Down

USER

Press [E] if selecting user adjustable range

▲

▼

Enter

100 PPM

Select [E] to select or ▲ or ▼ to select another and press [E]

▲

▼

4-20 mA Adjustment Example

Down

4-20mA

S.P. Function 4-20 mA Calibrator

▲

▼

Enter

Calib

S.P. Function - Calib Adjust

▲

▼

Enter

Out: 4mA

Use ▲ or ▼ keys to select 4 mA or 20mA

▲

▼

Enter

4mA

Selects 4 mA

▲

▼

Enter

ACK

Momentary Acknowledge of new Set Point

▲

▼

Figure 11: Set-Up Configuration

Model 4501-XX Toxic Gas Sensor Module

Page 19 of 41

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 the table below.

Key

Function

Display

Description

Reference

Mode

XXX PPM

Default Display (example (4501-05)

▲

▼

Mode

CALIB

Go to previous maintenance menu item

▲

▼

Mode

SETUP:

▲

▼

Mode

MAINT:

▲

▼

Enter

VX.XX

Version number of firmware

▲

▼

Enter

CCC001

Configuration Version

▲

▼

Figure 12: Maintenance Sub-Menu

Model 4501-XX Toxic Gas Sensor Module

Page 20 of 41

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 13) - used with portable calibrators.

CALIBRATION PROCEDURE

The Calibration Menu is described in Section 6.5:

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.

Sample Gas In

Figure 13: Model 5358-01

Calibration Adapter

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Sierra Monitor 4501-XX Electrochemical 2-Wire Toxic Gas Sensor Owner's manual

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Model: 4501-XX Electrochemical 2-Wire Toxic Gas Sensor

Category: Carbon monoxide (CO) detectors

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SMC 4501-XX Toxic Gas Detector

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Sierra Monitor 4501-XX Electrochemical 2-Wire Toxic Gas Sensor Owner's manual

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