RKI Instruments GasWatch 3 Operating Manual
GasWatch 3 for
Carbon Monoxide
Operator’s Manual
Part Number: 71-0485
Revision: P1
Released: 2/13/20
www.rkiinstruments.com
WARNING
Read and understand this instruction manual before operating
instrument. Improper use of the gas monitor could result in
bodily harm or death.
Maintenance of the gas monitor is essential for proper
operation and correct readings.
Bump test the instrument before each day’s use with a known
concentration of the target gas. A bump test can be done in User
Mode’s BUMP item or by applying gas in Measuring Mode.
The instrument does not need to be calibrated unless it does not
pass the User Mode bump test or does not respond
appropriately, as defined by the user, in Measuring Mode. For
more information about bump test and calibration
requirements, see IEC 60079-29-2.
GasWatch 3 for CO
Table of Contents
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
About the GasWatch 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Chapter 2: Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Instrument Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
LCD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Control Buttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Alarm LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Buzzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Vibrator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Infrared Communications Port. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Battery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Standard Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Alligator Clip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Watch Band. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Calibration Cup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
IrDA/USB Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Chapter 3: Measuring Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Turning On the GasWatch 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Performing a Demand Zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Turning Off the GasWatch 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Measuring Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Monitoring an Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Responding to Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Data Logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Chapter 4: Display Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Tips for Using Display Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Peak Screen (PEAK). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
STEL Screen (STEL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
TWA Screen (TWA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
GasWatch 3 for CO
User ID Screen (USER ID). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Station ID Screen (STN ID) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Last Successful Calibration Date (CAL.DATA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Last Successful Bump Test Screen (BP.DATA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Date/Time Screen (DATE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Temperature Screen (TEMP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Alarm Points Screen (ALARM--P) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Adjusting the Buzzer Volume (BUZZ.VOL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Chapter 5: User Mode and Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Entering User Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Tips for Using User Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Performing a Bump Test (BUMP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Performing a Calibration (GAS CAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Setting Calibration Parameters (CAL SET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Setting Bump Test Parameters (BUMP.SET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Alarm Settings (ALARM--P) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Updating the Lunch Break Setting (LUNCH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Setting the Confirmation Beep and Non-Compliance Indicator (BEEP) . . . . . . . . . . . . . 60
Updating the Backlight Time (BL TIME). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Turning the Key Tone On/Off (KEY.TONE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Display Mode Items (DISP.SET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Zero Suppression (ZERO.SUP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Zero Follower (ZERO.FLW) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Turning Easy Calibration On/Off (E-CAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Setting the Date/Time (DATE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Turning the Password On/Off (PASS-W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Viewing the ROM/SUM (ROM/SUM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Entering Measuring Mode (START) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Chapter 6: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
Replacing the Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Replacing the Charcoal Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Replacing the Hydrophobic Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Replacing the Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Chapter 7: General Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Appendix A: Maintenance Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Entering Maintenance Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Tips for Using Maintenance Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Performing a Calibration (GAS CAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Performing a Gas Test (GAS.TEST). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Sensor/Battery Replacement Date (SEN.DATE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
GasWatch 3 for CO
Performing a Bump Test (BUMP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Setting Alarms to Latching or Self-Resetting (LATCH) . . . . . . . . . . . . . . . . . . . . . . . . . 78
Turning the Demand Zero Function On/Off (D.ZERO). . . . . . . . . . . . . . . . . . . . . . . . . . 79
Turning the Auto Zero Function On/Off (A.ZERO). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Turning the ID Display Function On/Off (ID DISP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Turning the Zero Suppression On/Off (ZERO.SUP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Turning the Zero Follower On/Off (ZERO.FLW) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
User Mode Zero Suppression (ZSUP.DSP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
User Mode Zero Follower (ZFLW.DSP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Cylinder Setting (CYL.DISP). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Setting the Date/Time (DATE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Turning the Password On/Off (PASS-W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Viewing the ROM/SUM (ROM/SUM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Performing a Default (M.DEF). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Entering Measuring Mode (START) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Appendix B: Gas Select Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Entering Gas Select Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Tips for Using Gas Select Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Saving the Alarm Points (SAVE-AP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Turning the Calibration Max Span On/Off (MAX.SPAN) . . . . . . . . . . . . . . . . . . . . . . . . 86
Stealth and Vibrator Settings (STEALTH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Exiting Gas Select Mode (START). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
WARNING: Understand manual before operating. This is an intrinsically safe product.
Substitution of components may impair intrinsic safety. T o prev ent ignition
of a hazardous atmosphere, batteries must only be changed or charged in
an area known to be nonhazardous. Not tested in oxygen enriched
atmospheres (above 21%).
AVERTISSEMENT:Comprendre le manuel avant de l'utiliser. Ceci est un produit
intrinsèquement sûr. La substitution de composants peut nuire à la sécurit é
intrinsèque. Pour éviter l'inflammation d'une atmosphère dangereuse, les
batteries ne doivent être remplacées ou chargées que dans une zone non
dangereuse. Non testé dans des atmosphères enrichies en oxygène (plus de
21%).
GasWatch 3 for CO
Chapter 1: Introduction
Overview
This chapter briefly describes the GasWatch 3 gas monitor. This chapter also describes the
GasWatch 3 Operator’s Manual (this document). Table 1 at the end of this chapter lists the
specifications for the GasWatch 3.
About the GasWatch 3
Using an advanced detection system, the GasWatch 3 personal gas monitor detects the
presence of carbon monoxide (CO). The GasWatch 3’s compact size and easy-to-use design
make it ideally suited for a wide range of applications, including sewage treatment plants,
utility manholes, tunnels, hazardous waste sites, power stations, petrochemical refineries,
mines, paper mills, drilling rigs, and fire fighting stations. The GasWatch 3 offers a full range
of features, including:
• Liquid crystal display (LCD) for complete and understandable information at a glance
• Ultrabright alarm LEDs
• Distinctive audible/vibrating alarms for dangerous gas conditions and audible alarms for
unit malfunction
• Microprocessor control for reliability, ease of use, and advanced capabilities
• Data logging functions
• Alarm trend data
• STEL, TWA, and over range alarms
• Peak reading
• Built-in time function
• Lunch break feature
• CSA “C/US” classification for Class I, Division I, Groups A, B, C, and D hazardous
atmospheres
WARNING: The Model GasWatch 3 detects elevated levels of carbon monoxide which
can be dangerous or life threatening. When using the GasWatch 3, you
must follow the instructions and warnings in this manual to assure proper
and safe operation of the unit and to minimize the risk of personal injury.
Be sure to maintain and periodically calibrate the GasWatch 3 as described
in this manual.
AVERTISSEMENT:Le modèle GasWatch 3 détecte les niveaux élevés de monoxyde de
carbone qui peuvent être dangereux ou mettre la vie en danger. Lorsque
vous utilisez le GasWatch 3, vous devez suivre les instructions et les
avertissements de ce manuel pour assurer un fonctionnement correct et en
toute sécurité de l'appareil et pour réduire les risques de blessures. A ssurezvous de maintenir et d’étalonner périodiquement le GasWatch 3 comme
décrit dans ce manuel.
6 • Chapter 1: In troduction GasWatch 3 for CO
Specifications
Table 1: Standard Sensor Specifications/Alarm Points
Detection Range 0 - 300 ppm
Service Range 310 - 2,000 ppm
Reading Increment 0 - 300 ppm: 1 ppm
310 - 2,000 ppm: 10 ppm
Warning Factory Setting 25 ppm
Alarm Factory Setting 50 ppm
Alarm H Factory Setting 1200 ppm
STEL Alarm 200 ppm
TWA Alarm 25 ppm
Table 2: GasWatch 3 Specifications
Sampling
Method
Response Time T90 Within 10 Seconds
Display Graphics LCD Display
Operating
Temperature
& Humidity
Indication
Accuracy
Safety/
Regulatory
Continuous environment: -20°C to 50
Temporary environment (up to 15 minutes): -20°C to 60
Detection Range: ± 5% of reading or ± 5 ppm CO (whichever is greater)
Service Range: ± 20% of reading
• ATEX: II 1G Ex ia IIC T4 Ga
Certificate Number Presafe DEKRA 18ATEX0130
• IECEx: Ex ia IIC T4 Ga
Certificate Number IECEx DEK 18.0082
• CSA classified, “C/US”, as Intrinsically Safe. Exia. Class I, Groups A, B, C, & D.
Temperature Code T3A.
Certificate Number CSA 19 CA70213062
Diffusion
°
C/10 to 90% RH
C US
186718
°
C/0 to 95% RH
Power Supply CR2450 button cell battery
Continuous
Operating
Hours
@ 25 °C
Case High-impact Plastic, RF Shielded, Dust and Weather Proof (IP66/68)
4,000 hours in Measuring Mode (Non Alarm Operation, Fully Charged)
GasWatch 3 for CO Chapter 1: Introduction • 7
Standard
Accessories
• Alligator clip
Optional
Accessories
Dimensions
and Weight
• Watch band
• Calibration cup
• Datalogging and Setup Programs (Windows
www.rkiinstruments.com/gw3
• IrDA/USB Cable for connecting to a computer when using the Datalogging and Setup
Programs (not needed if computer has an infrared port)
About this Manual
The GasWatch 3 Operator’s Manual uses the following conventions for notes, cautions, and
warnings.
NOTE: Describes additional or critical information.
CAUTION: Describes potential damage to equipment.
®
7, 8, and 10), available at
Approximately 42(H) x 63(W) x 22(D) mm (1.7”H x 2.5”W x 0.9”D)
Approximately 45 g (1.6 oz.)
WARNING: Describes potential danger that can result in injury or death.
8 • Chapter 1: In troduction GasWatch 3 for CO
Chapter 2: Description
Figure 1: Component Location
Alarm LED s and IrDA Port
Sensor Retainer
Sensor Opening
LCD
Buzzer
Opening
AIR Button
POWER/MODE Button
Overview
This chapter describes the GasWatch 3 instrument and its accessories.
Instrument Description
Case
The GasWatch 3’s sturdy, high-impact plastic case is radio frequency (RF) resistant and is
suitable for use in many environmental conditions, indoors and out. The case is dust proof and
water resistant. A clear plastic window is located on the front of the case for viewing the LCD.
The sensor retainer is located on the right side of the case and allows access to the filters and
sensor.
LCD
A digital LCD (liquid crystal display) is visible through a clear plastic window in the top case.
The LCD shows the gas reading. The LCD also shows information for each of the GasWatch
3’s operating modes.
GasWatch 3 for CO Chapter 2: Description • 9
Control Buttons
Two control buttons, AIR and POWER/MODE, are located below the LCD.
Table 3: GasWatch 3 Control Button Functions
Button Function(s)
AIR • turns on LCD backlight
• resets alarm condition if LATCH is set to ON in Maintenance Mode
• enters User Mode, Maintenance Mode, and Gas Select Mode when used
with POWER/MODE
• activates the demand zero function (adjusts the GasWatch 3’s fresh air
reading)
• changes the value of a parameter available for adjustment
• scrolls through parameter options
POWER/MODE • turns the GasWatch 3 on and off
• turns on LCD backlight
• enters and scrolls through Display Mode
• enters instructions into the GasWatch 3’s microprocessor
• resets alarm condition if LATCH is set to ON in Maintenance Mode
• enters User Mode, Maintenance Mode, and Gas Select Mode when used
with AIR
Alarm LEDs
The two alarm LEDs above the LCD alert you to gas, low battery, and failure alarms.
Buzzer
One solid-state electronic buzzer is located inside the case. Sound exits the case through a
hole in the middle front of the case. The buzzer sounds for gas alarms, malfunctions, and low
battery voltage. It also provides feedback for button presses and while in Display, User,
Maintenance, or Gas Select Mode.
Vibrator
A vibrating motor inside the GasWatch 3 case vibrates for gas alarms and unit malfunctions.
NOTE: If STEALTH is set to ON, the vibrator only functions when VIB in the STEALTH
Gas Select Mode item is set to ON (see pg.87).
Sensor
The sensor retainer holds the sensor in its socket. The CO sensor is an electrochemical cell
that consists of two precious metal electrodes in a dilute acid electrolyte. A gas permeable
membrane covers the sensor face and allows gas to diffuse into the electrolyte. The gas reacts
in the sensor and produces a current proportional to the concentration of the target gas. The
GasWatch 3’s circuitry amplifies the current, converts the current to a gas concentration, and
displays the concentration on the LCD.
Filters
Charcoal Filter (Black)
A black charcoal filter is placed into a recess in the filter gasket over the CO sensor. The
charcoal filter disk scrubs H
10 • Chapter 2: Description GasWatch 3 for CO
S and certain hydrocarbons out of the sample to avoid false CO
2
readings. If false or elevated CO readings are noticed, especially in the presence of H2S,
change the charcoal filter.
Hydrophobic Filter
The white, circular hydrophobic filter sits on the filter gasket, covering the sensor port and the
charcoal filter.
Infrared Communications Port
An infrared (IR) communications port is located at the top of the instrument, near the LEDs.
Logged data transmits through the port in standard IrDA protocol. A computer’s infrared port
or an IrDA/USB cable connected to a USB port can be used to download data to the GasWatch
3 Datalogging Program. See the GasWatch 3 Datalogging Program operator’s manual for data
logging and downloading instructions.
Battery
A user-replaceable CR2450 button cell battery powers the GasWatch 3. At 25°C the battery
lasts at least 4,000 hours (166 days). The battery icon in the upper right of the LCD shows
remaining battery life.
A low battery warning activates when the GasWatch 3 detects a low battery voltage. The
GasWatch 3 sounds a dead battery alarm when battery voltage is too low for Measuring Mode.
NOTE: Use of batteries not specified by RKI Instruments, Inc. compromises the CSA
classification and may void the warranty. See “Replacing the Battery” on page 67.
WARNING: To prevent ignition of a hazardous atmosphere, the battery must only be
changed in an area known to be nonhazardous.
AVERTISSEMENT:Pour éviter l'inflammation d'une atmosphère dangereuse, la batterie
ne doit être remplacée que dans une zone non dangereuse.
GasWatch 3 for CO Chapter 2: Description • 11
Standard Accessories
Alligator Clip
Base Clip
Figure 2: Alligator Clip
Figure 3: Watch Band
Alligator Clip
An alligator clip is installed to a base clip that attaches to spring bars on the back of the
GasWatch 3. Use the alligator clip to attach the GasWatch 3 to clothing or a belt. Teeth in the
alligator clip’s jaws prevent slipping. The alligator clip can be rotated to change the
instrument’s orientation.
Optional Accessories
Watch Band
The adjustable watch band allows the GasWatch 3 to be worn on the wrist. The watch band
attaches to spring bars that are protected by hollow tubes.
12 • Chapter 2: Description GasWatch 3 for CO
Calibration Cup
FLOW
Figure 4: Calibration Cup
The calibration cup installs over the sensor. You must use the calibration cup when performing
a bump test, calibration, or gas test.
IrDA/USB Cable
Unless your computer has a built-in IrDA port, a IrDA/USB cable is needed to establish
communication between the GasWatch 3 and the Datalogging Program or the Setup Program.
GasWatch 3 for CO Chapter 2: Description • 13
Chapter 3: Measuring Mode
RESUME
SEC
5
YES .MODE
SEC
5
NO .AIR
SEC
5
Overview
This chapter explains how to use the GasWatch 3 to perform confined space entry monitoring
or general area monitoring in Measuring Mode.
Start Up
This section explains how to start up the GasWatch 3, get it ready for operation, and turn it off.
Turning On the GasWatch 3
To illustrate certain functions, the following description of the GasWatch 3 start up sequence
assumes that the following items in User Mode are turned on: LUNCH, CAL.RMDR, and
BP.RMDR in User Mode, and ID DISP and A.ZERO in Maintenance Mode. If any of these
items are turned off, then the corresponding screens do not appear.
1. Press and briefly hold down POWER/MODE. Release the button when you hear a beep.
2. If LUNCH is set to ON (factory setting if OFF, see pg.59), the Lunch Break Screen
appears. The unit counts down from 5 seconds.
a. Continue Accumulating: To continue accumulating peak and time-weighted average
(TWA) readings from the last time the GasWatch 3 was used, press and release
POWER/MODE or allow the countdown to reach 0. The short-term exposure limit
(STEL) reading is reset each time the GasWatch 3 is turned on.
b. Reset Accumulation
(TWA) readings, press and release AIR before the countdown reaches 0.
: To reset the accumulation of peak and time-weighted average
14 • Chapter 3: Measuring Mode GasWatch 3 for CO
3. If CAL.RMDR is set to ON (factory setting) and a calibration is due, the screen that
CAL - LMT
CAL
CAL - LMT
FAIL
NEXT .CAL
d
0
appears next depends on how CAL.EXPD is set in User Mode (see pg.52). The three
possible screens are described below. If a calibration is not due, the instrument displays
the number of days left until a calibration is due.
CAL.EXPD set to
CONFIRM (factory setting)
LCD
Sound Buzzer sounds double pulsing
tone
Action • Option A, Perform calibration
Press and release POWER/
MODE to enter User Mode
and perform a calibration. The
instrument takes you straight
to the calibration start screen
in User Mode’s GAS CAL\ACAL(E-CAL) item. See pg.42
for calibration instructions.
NOTE: If Password Protection
is set ton On (factory setting is
Off) using the GW-3 Config Program, you will be prompted for a
password to enter User Mode.
If the calibration is success-
ful, the screen above will not
appear again until the unit is
due for calibration. If the cali-
bration is not successful, the
screen above will again appear
in the startup sequence.
• Option B, Bypass message
continue without performing a
calibration, press and release
AIR.
: To
CAL.EXPD set to
CANT.USE
Buzzer sounds double pulsing
tone
The GasWatch 3 cannot be used
:
until a successful calibration is
performed. Press and release
POWER/MODE to enter User
Mode and perform a calibration.
The instrument takes you straight
to the calibration start screen in
User Mode’s GAS CAL/A-CAL
(E-CAL) item. If you don’t press
POWER/MODE, the instrument
automatically goes to the calibra-
tion start screen after 6 seconds.
See pg.42 for calibration instruc-
tions.
NOTE: If Password Protection is
set ton On (factory setting is Off)
using the GW-3 Con f ig P rogram,
you will be prompted for a password to enter User Mode.
If the calibration is successful,
the screen above will not appear
again until the unit is due for cali-
bration. If the calibration is not
successful, the screen above will
again appear in the startup
sequence.
CAL.EXPD set to
NONE
None
• Option A, Perform calibration
If you want to enter User
Mode and perform a
calibration, press and release
POWER/MODE. The
instrument takes you straight
to the calibration start screen
in User Mode’s GAS CAL/ACAL (E-CAL) item.
• Option B, Bypass message
To continue without
performing a calibration, wait
a few seconds for the
instrument to continue with its
startup sequence.
:
:
GasWatch 3 for CO Chapter 3: Measuring Mode • 15
4. If BP.RMDR is set to ON (factory setting is OFF) and a bump test is due, the screen that
BP - LMT
CAL
BP - LMT
FAIL
NEXT .BP
d
0
10:42
2 . 13
2019
appears next depends on how BP.EXPD is set in User Mode (see pg.56). The three
possible screens are described below. If a bump test is not due, the instrument displays the
number of days left until a bump test is due.
BP.EXPD set to
CONFIRM (factory setting)
LCD
Sound Buzzer sounds double pulsing
tone
Action • Option A, Perform bump test
Press and release POWER/
MODE to enter User Mode
and perform a bump test. The
instrument takes you straight
to the bump test start screen in
User Mode’s BUMP item. See
pg.37 for bump test
instructions.
NOTE: If Password Protection
is set ton On (factory setting is
Off) using the GW-3 Config Program, you will be prompted for a
password to enter User Mode.
If the bump test is successful,
the screen above will not
appear again until the unit is
due for bump testing. If the
bump test is not successful,
the screen above will again
appear in the startup sequence.
• Option B, Bypass message
continue without performing a
bump test, press and release
AIR.
: To
BP.EXPD set to
CANT.USE
Buzzer sounds double pulsing
tone
The GasWatch 3 cannot be used
:
until a successful bump test is
performed. Press and release
POWER/MODE to enter User
Mode and perform a bump test.
The instrument takes you
straight to the bump test start
screen in User Mode’s BUMP
item. If you don’t press
POWER/MODE, the instrument
automatically goes to the bump
test start screen after 6 seconds.
See pg.37 for bump test instruc-
tions.
NOTE: If Password Protection
is set ton On (factory setting is
Off) using the GW-3 Config Program, you will be pr omp ted for a
password to enter User Mode.
If the bump test is successful, the
screen above will not appear
again until the unit is due for
bump testing. If the bump test is
not successful, the screen above
will again appear in the startup
sequence.
BP.EXPD set to
NONE
None
• Option A, Perform bump test
If you want to enter User
Mode and perform a bump
test, press and release
POWER/MODE. The
instrument takes you straight
to the bump test start screen in
User Mode’s BUMP item.
• Option B, Bypass message
To continue without
performing a bump test, wait
a few seconds for the
instrument to continue with its
startup sequence.
:
:
5. The Date/Time Screen appears for a few seconds.
16 • Chapter 3: Measuring Mode GasWatch 3 for CO
6. The Battery Voltage Screen appears for a few seconds. An “AL-L” at the bottom of the
AL-L
2.9
V
bAtt
CO
ppm
F .S .
1000
CO
ppm
WARNING
25
CO
ppm
ALARM
50
CO
ppm
ALARM H
1200
CO
ppm
STEL
200
CO
ppm
TWA
25
CO
ppm
UID_001
Id
USER
SID_001
Id
StN
SENSOR
FAIL
CO
ppm
screen indicates that the alarms are set to latching. An “AL-A” at the bottom of the screen
indicates that the alarms are set to auto reset. See pg.78 for a description of how to change
this parameter.
7. The following screens display for 1 second each: Gas Name, Full Scale, Warning Setpoint,
Alarm Setpoint, Alarm H Setpoint, STEL Setpoint, and TWA Setpoint.
8. If ID DISP is set to ON (factory setting is OFF, see pg.80), the User ID Screen appears
for a few seconds, followed by the Station ID Screen.
9. If the GasWatch 3 experiences a sensor failure during start up, a screen indicating that the
sensor failed appears and the buzzer sounds a double pulsing tone once per second.
GasWatch 3 for CO Chapter 3: Measuring Mode • 17
You cannot acknowledge the failure and continue to Measuring Mode. Replace the failed
sensor as soon as possible.
10. If A.ZERO is set to ON (factory setting is OFF, see pg.79), the instrument prompts you to
A.ZERO
YES .MODE
NO .AIR
10:42
0
CO
ppm
do an auto zero. An auto zero operation sets the reading to 0 ppm.
WARNING: Make sure that the instrument is in a known fresh air environment (an
environment free of combustible or toxic gases and of normal oxygen
content, 20.9%) before performing an auto zero operation. If you perform
an auto zero operation in an area with gases present, the adjustment will
not be accurate.
You must press and release the POWER/MODE button to perform an auto zero function.
If you do not press any key, after 15 seconds, the instrument enters Measuring Mode
without performing an auto zero.
11. The GasWatch 3 is now monitoring for gas in Measuring Mode. The Measuring Mode
Screen displays the current gas reading.
Performing a Demand Zero
Perform a demand zero before using the GasWatch 3. This sets the reading to 0 ppm.
1. Find a fresh-air environment. This is an environment free of toxic or combustible gases
and of normal oxygen content (20.9%).
2. Turn on the unit as described above in “Turning On the GasWatch 3”.
3. Press and hold AIR. The buzzer pulses and the LCD prompts you to continue holding AIR
(if KEY.TONE is set to ON in User Mode).
4. Continue to hold AIR until the LCD prompts you to release it. The GasWatch 3 sets the
fresh air reading. Start up is complete and the unit is now ready for monitoring.
Turning Off the GasWatch 3
1. Press and hold POWER/MODE.
18 • Chapter 3: Measuring Mode GasWatch 3 for CO
2. OFF appears on the display and the buzzer pulses for about five seconds (if KEY.TONE
is set to ON in User Mode).
3. Release the button when OFF disappears from the display.
4. If Password Protection is turned On (factory setting is Off) using the GW-3 Setup
PASS--W
0 0 0 0
S. 10:42
0
CO
ppm
10:42
0
CO
ppm
Program, a user-set password is required to turn off the GasWatch 3. When the password
screen appears, adjust each digit with the AIR button and press and release the POWER/
MODE button to move on to the next digit. Once the password is entered, the instrument
shuts off.
Measuring Mode Operation
When the GasWatch 3 completes its startup sequence, it is in Measuring Mode. In Measuring
Mode the GasWatch 3 continuously monitors the sampled atmosphere and displays the gas
concentration. The GasWatch 3 is in Normal Operation if there are no alarm indications.
Heart Symbol: The heart symbol on the right side of the LCD indicates the operation status
and flashes when normal. A microprocessor error causes the heart symbol to stop flashing or
to disappear.
Check Mark: If BP.RMDR is set to ON and if a bump test is not due, a check mark appears in
the lower left corner of the LCD.
“S”: If the instrument is operating in Stealth Mode, an “S.” appears at the bottom of the LCD.
Backlight: In a low-light environment, press and release either button to turn on the display
backlight. See pg.61 to program backlight duration.
Confirmation/Non-Compliance Indicator: If the BEEP item in User Mode is set to anything
other than OFF, the GasWatch 3 gives periodic indications to confirm that it’s operating or to
indicate a non-compliance (see pg.60).
Monitoring an Area
1. Start up the GasWatch 3 as described above in “Start Up” on page 14. It is now in
Measuring Mode.
2. Take the GasWatch 3 to the monitoring area.
3. Wait at least 15 seconds.
GasWatch 3 for CO Chapter 3: Measuring Mode • 19
Alarms
4. If a reading is observed, allow the reading to stabilize to determine the gas concentration
present.
5. If a gas alarm occurs, take appropriate action. See pg.22.
This section covers alarm indications in Measuring Mode. It also describes how to reset the
GasWatch 3 after an alarm occurs and how to respond to an alarm condition.
NOTE: False alarms may be caused by radio frequency (RF) or electromagnetic (EMI)
interference. Keep the GasWatch 3 away from RF and EMI sources such as radio
transmitters or large motors.
Alarm Indications
The GasWatch 3 buzzer sounds an alarm, the LEDs flash, and the vibrator pulses when any
sort of alarm condition or failure occurs. If the GasWatch 3 is operating in Stealth Mode, the
buzzer does not sound and the vibrator’s operation depends on the VIB setting in Gas Select
Mode’s STEALTH item. See pg.87 for more information.
NOTE: If an alarm condition occurs while you are in Display Mode, the GasWatch 3
automatically returns to the Measuring Mode screen.
The table below summarizes the types of alarms produced by the GasWatch 3 and their
indications.
Table 4: Alarm Types and Indications
Alarm Type Visual Indications Other Indications
Warn ing
Concentration of gas rises above
the Warning setting.
Alarm
Concentration of gas rises above
the Alarm setting.
Alarm H
Concentration of gas rises above
the Alarm H setting.
• Gas reading flashes
• WARNING appears at the bottom of
the LCD
• Alarm LEDs flash once per second
• Backlight turns on
• Gas reading flashes
• ALARM appears at the bottom of the
LCD
• Alarm LEDs flash twice per second
• Backlight turns on
• Gas reading flashes
• ALARM H appears at the bottom of
the LCD
• Alarm LEDs flash twice per second
• Backlight turns on
• High-low tone sounds
once per second
• Vibrator pulses once per
second
• High-low tone sounds
twice per second
• Vibrator pulses twice per
second
• High-low tone sounds
twice per second
• Vibrator pulses twice per
second
20 • Chapter 3: Measuring Mode GasWatch 3 for CO
Table 4: Alarm Types and Indications
Alarm Type Visual Indications Other Indications
TWA or STEL
Concentration rises above the TWA
or STEL alarm setting.
Over Range
Minus Over Range
Low Battery Warning
• Gas reading flashes
• TWA or STEL appears at the bottom
of the LCD
• Alarm LEDs flash once per second
• Backlight turns on
• Gas reading is replaced with a
flashing
• Gas name and units flash
• OVER appears at the bottom of the
LCD
• Alarm LEDs flash twice per second
• Backlight turns on
• Affected channel’s gas reading is
replaced with a flashing
• Gas name and units flash
• M OVER appears at the bottom of
the LCD
• Alarm LEDs flash twice per second
• Backlight turns on
• The last bar in the battery icon
disappears and the battery icon starts
flashing
• High-low tone sounds
once per second
• Vibrator pulses once per
second
• High-low tone sounds
twice per second
• Vibrator pulses twice per
second
• High-low tone sounds
twice per second
• Vibrator pulses twice per
second
None
Dead Battery Alarm
Sensor Failure
Clock Failure
System Failure
• Gas reading disappears. FAIL
BATTERY appears on the LCD.
• Alarm LEDs flash once per second
• FAIL SENSO R appears on the LCD.
• Alarm LEDs flash once per second
• FAIL 050 CLOCK appears on the
LCD
• Alarm LEDs flash once per second
•FAIL SYSTEM and an error code
appear on the LCD
• Alarm LEDs flash once per second
Double pulsing tone sounds
once per second
Double pulsing tone sounds
once per second
Double pulsing tone sounds
once per second
Double pulsing tone sounds
once per second
GasWatch 3 for CO Chapter 3: Measuring Mode • 21
Responding to Alarms
This section describes response to gas, over range, battery, sensor failure, clock failure, and
system failure alarms.
Responding to Gas Alarms
1. Follow your established procedure for an increasing gas condition.
2. Reset the alarm as necessary or allowed.
a. If LATCH is set to ON (factory setting) in Maintenance Mode, the gas reading must
fall below an alarm setting before you can reset the alarm condition using POWER/
MODE or AIR.
If Password Protection is set to On using the GW-3 Config Program, you must press
AIR and POWER/MODE at the same time and then enter a user-set password to reset
the gas alarm.
b. If LATCH is set to OFF in Maintenance Mode, the alarm condition automatically
resets when gas reading falls below an alarm setpoint.
Responding to Over Range Alarms
WARNING: An over range condition may indicate an extreme carbon monoxide
concentration or an explosive concentration. Confirm the gas
concentration with a different GasWatch 3 or with another gas detecting
device.
AVERTISSEMENT:Un dépassement de la plage peut indiquer une concentration extrême
en monoxyde de carbone ou une concentration en explosif. Confirmez la
concentration de gaz avec un GasWatch 3 différent ou avec un autre
dispositif de détection de gaz.
1. Follow your established procedure for an extreme gas condition.
2. Reset the alarm using POWER/MODE or AIR once the alarm condition clears if LATCH
is set to ON (factory setting) in Maintenance Mode.
If Password Protection is set to On using the GW-3 Config Program, you must press AIR
and POWER/MODE at the same time and then enter a user-set password to reset the over
range alarm.
3. Calibrate the GasWatch 3 as described on pg.42.
4. If the over range condition continues or if you are not able to successfully calibrate the
unit, you may need to replace the sensor.
5. If the over range condition continues after you replace the sensor, contact RKI
Instruments, Inc. for further instructions.
22 • Chapter 3: Measuring Mode GasWatch 3 for CO
Responding to Battery Alarms
CLOCK
050
FAIL
SYSTEM
031
FAIL
WARNING: The GasWatch 3 is not operational as a gas monitoring device during a
dead battery alarm. Take the GasWatch 3 to a non-hazardous area and
replace the battery as described in “Replacing the Battery” on page 67.
The GasWatch 3 is fully functional during a low battery warning. However, only 10 days of
operating time remain. The amount of time depends on LCD backlight use and alarm
frequency. Replace the battery as described on pg.67 as soon as possible.
NOTE: Alarms and the LCD backlight consume battery power and reduce the amount of
operating time remaining.
Responding to Sensor Failure Alarms
1. Calibrate the sensor as described on pg.42.
2. If the sensor failure continues, replace the sensor as described on pg.71.
3. If the sensor failure condition continues after replacing the sensor, contact RKI
Instruments, Inc. for further instructions.
Responding to Clock Failure Alarms
A clock failure alarm occurs if the unit’s internal clock malfunctions.
1. Press and release POWER/MODE to continue into Measuring Mode.
CAUTION: There is no datalogging function if you operate the instrument after a clock
failure.
2. Attempt to set the date using the DATE item in User Mode (see pg.63).
3. If the date cannot be set correctly, contact RKI Instruments, Inc. as soon as possible.
Responding to System Failure Alarms
1. If a system failure occurs, the system failure screen displays an error code as shown
below:
GasWatch 3 for CO Chapter 3: Measuring Mode • 23
2. The error code meanings are shown in the table below:
Table 5: Error Code Explanation
Error Code Explanation
000 ROM failure
010 RAM failure
020 FRAM failure
031 FLASH memory failure
082 Temperature sensor failure
3. If the error code is anything but 031, the instrument cannot be used. Contact RKI
Instruments, Inc. as soon as possible.
If the error code is 031, press and release POWER/MODE to continue into Measuring
Mode if the instrument must be used temporarily.
CAUTION: There is no datalogging function if you operate the instrument after a 031
system failure. Contact RKI Instruments, Inc. as soon as possible.
Data Logging
The GasWatch 3 logs Measuring Mode gas readings, alarm data, and calibration data to its
internal memory. Logged data can be download it to a computer via the infrared
communications port on the front of the unit.
The data logging capacity depends on how often the GasWatch 3 stores data and how often the
GasWatch 3 is turned on and off. The table below illustrates how much data logging time is
available for the various interval times. It assumes that the unit is only turned on once and
there are no alarms. The data logging interval time must be set using the GasWatch 3
Datalogging Program.
Table 6: Data Logging Capacity
Interval Time Data Logging Capacity
10 seconds 10 hours
20 seconds 20 hours
30 seconds 30 hours
1 minute 60 hours
3 minutes 180 hours
5 minutes 300 hours
10 minutes 600 hours
24 • Chapter 3: Measuring Mode GasWatch 3 for CO
To utilize the GasWatch 3’s downloading capability, you need:
• PC with Windows 7, Windows 8, or Windows 10
• IrDA port or IrDA/USB cable (cable available from RKI Instruments, Inc.)
• GasWatch 3 Datalogging Program (available at www.rkiinstruments.com/gw3).
For a complete description of the Datalogging Program and procedures for downloading data
to a computer, see the GasWatch 3 Datalogging Program Operator’s Manual.
GasWatch 3 for CO Chapter 3: Measuring Mode • 25
Chapter 4: Display Mode
This section describes Display Mode which is accessible from Measuring Mode. See Table 7
below for a list of Display Mode’s menu items, a short description of each item, and the page
number for further description.
Table 7: Display Mode Menu Items
Display Mode
Menu Item
PEAK (pg.27) Displays the Peak reading.
STEL (pg.27) Displays the STEL reading.
TWA (pg.28) Displays the TWA reading.
USER ID
A
(pg.28)
STN ID
A
(pg.29)
CAL.DATA
B
(pg.30)
BP.DATA
C
(pg.30)
DATE (pg.31) Displays the current date and time.
TEMP (pg.31) Displays the current temperature.
ALARM--P
(pg.31)
View and/or change the User ID.
View and/or change the Station ID.
Displays the last calibration date.
Displays the last bump test date.
View alarm points.
Description
BUZZ.VOL
D
(pg.32)
A
Only appears if DISP.SET is set to ON in User Mode (factory setting) and if ID DISP is set to ON in
Maintenance Mode (factory setting is OFF).
B
Only appears if CAL.RMDR is set to ON in User Mode (factory setting).
C
Only appears if BP.RMDR is set to ON in User Mode (factory setting is OFF).
D
Only appears if DISP.SET is set to ON in User Mode (facto ry setting).
Set the buzzer volume to LO or HI (factory setting).
Tips for Using Display Mode
• To enter Display Mode and scroll from one item to the next or skip an item when a
question is asked, press and release POWER/MODE.
• To enter an item, press and release AIR.
• To change a flashing parameter, press and release AIR. To reverse the movement in a list
(ie. from down to up or vice versa):
a. Press and hold AIR.
b. Immediately press POWER/MODE and then release both buttons.
26 • Chapter 4: Display Mode GasWatch 3 for CO
• To exit from an entered-information screen and go back to Measuring Mode, press and
PEAK
135
CO
ppm
HOLD
CLR
RELEASE
CLR
STEL
10
CO
ppm
release POWER/MODE until you get to the Measuring Mode screen.
NOTE: Each screen displays for 20 seconds. If you do not press a button within 20 seconds,
the GasWatch 3 automatically returns to Measuring Mode.
Peak Screen (PEAK)
The peak screen displays the highest concentration detected since the GasWatch 3 was turned
on. The peak reading is stored until a higher level is detected, the peak reading is cleared, or
the GasWatch 3 is turned off.
The lunch break feature enables the GasWatch 3 to save the peak reading when it is turned off
so it can continue with the same peak when it is turned on again (see pg.14).
To clear the peak reading, do the following:
1. After entering Display Mode, press and release POWER/MODE until PEAK appears.
2. Press and hold AIR until the screen prompts you to release it.
3. The peak reading is reset and the unit returns to the Peak Screen.
If you do not want to clear the peak reading, release AIR before the above screen sequence
occurs. The unit returns to the Peak Screen.
STEL Screen (STEL)
The STEL Screen displays the short term exposure limit (STEL) reading. The STEL reading
is the average reading over the last 15 minutes.
GasWatch 3 for CO Chapter 4: Display Mode • 27
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