RKI Instruments 72-RA-C User manual

www.rkiinstruments.com
GX-3R
Operator’s Manual
Part Number: 71-0477
Revision: P16
Released: 12/27/21

GX-3R Operator’s Manual
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 each 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.

GX-3R Operator’s Manual
Table of Contents
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
About the GX-3R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 2: Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Instrument Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
LCD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Control Buttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Alarm LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Buzzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Vibrator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Infrared Communications Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Charging Socket and Battery Pack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Included Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Alligator Clip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Rubber Boot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Wrist Strap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Single-Unit AC Charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Calibration Cup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Other Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
12 VDC Charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Multi-Unit AC Charger. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Belt Clip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
SDM-3R. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
RP-3R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Aspirator Adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
IrDA Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Chapter 3: Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Turning On the GX-3R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Performing a Demand Zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Turning Off the GX-3R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Measuring Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Monitoring an Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Combustible Gas Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Oxygen-Enriched Atmospheres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

GX-3R Operator’s Manual
H2-Compensated CO Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Interference Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Aspirator Adapter Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Responding to Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Data Logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Chapter 4: Display Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Tips for Using Display Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Peak Screen (PEAK). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
STEL Screen (STEL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
TWA Screen (TWA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Combustible Sensor Target Gas Conversion (LIST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Changing the User ID (USER ID) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Changing the Station ID (STN ID) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Last Successful Calibration Date (CAL DATA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Last Successful Bump Test Date (BUMP DATA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Date, Time, and Temperature Screen (TEMP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Viewing Alarm Settings Screen (ALARM--PT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Chapter 5: User Mode and Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Entering User Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Tips for Using User Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Performing a Bump Test (BUMP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Performing a Calibration (GAS CAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Setting Calibration Parameters (CAL SET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Setting Bump Test Parameters (BUMP SET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Alarm Settings (ALARM--PT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Updating the Lunch Break Setting (LUNCH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Setting the Confirmation Beep and Non-Compliance Indicator (BEEP) . . . . . . . . . . . . . 75
Updating the Backlight Time (BL TIME). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Turning the Key Tone On/Off (KEY TONE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Display Mode Items (DISP SET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Zero Suppression (ZERO SUP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Zero Follower (ZERO.FLWR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Setting the Date/Time (DATE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Turning the Password On/Off (PASSWORD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Viewing the ROM/SUM (ROM/SUM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Entering Measuring Mode (START) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Chapter 6: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Instrument Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Recharging the Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

GX-3R Operator’s Manual
Replacing the Buzzer Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Replacing the Sensor Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Replacing the Hydrophobic Dust Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Replacing a Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Replacing the Battery Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Chapter 7: Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Chapter 8: General Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Appendix A: Maintenance Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Entering Maintenance Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Tips for Using Maintenance Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Performing a Calibration (GAS CAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Performing a Gas Test (GAS TEST). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Sensor/Battery Replacement Date (SEN DATE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Performing a Bump Test (BUMP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Setting Alarms to Latching or Self-Resetting (LATCHING) . . . . . . . . . . . . . . . . . . . . . 103
Turning the Demand Zero Function On/Off (DEM ZERO) . . . . . . . . . . . . . . . . . . . . . . 103
Turning the Auto Zero Function On/Off (AUTOZERO) . . . . . . . . . . . . . . . . . . . . . . . . 104
Turning the ID Display Function On/Off (ID DISP) . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Turning the Zero Suppression On/Off (ZERO SUP) . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Turning the Zero Follower On/Off (ZERO.FLWR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
User Mode Zero Suppression (ZSUP.DISP). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
User Mode Zero Follower (ZFLW.DISP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Setting the Date/Time (DATE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Turning the Password On/Off (PASSWORD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Viewing the ROM/SUM (ROM/SUM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Performing a Default (M.DEFAULT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Entering Measuring Mode (START) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Appendix B: Gas Select Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Entering Gas Select Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Tips for Using Gas Select Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Changing the Gas Combination (GAS COMB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Saving the Alarm Points (SAVE-AP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Turning Calibration Max Span On/Off (MAX SPAN) . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Stealth and Vibrator Settings (STEALTH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
LEL Definition (CHG LEL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Exiting Gas Select Mode (START). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

6 • GX-3R Operator’s Manual
Appendix C: Interference Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
ESR-A13i-H2S, H2S Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
ESR-A13P-CO, CO Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
ESR-A1CP-COH, H2-Compensated CO Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
ESR-A1DP-COHS, CO Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
ESR-A1DP-COHS, H2S Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
WARNING: Understand manual before operating. Substitution of components may
impair intrinsic safety. To prevent ignition of a hazardous atmosphere,
batteries must only be changed or charged in an area known to be
nonhazardous.

GX-3R Operator’s Manual Chapter 1: Introduction • 7
Chapter 1: Introduction
Overview
This chapter briefly describes the GX-3R gas monitor. This chapter also describes the
GX-3R Operator’s Manual (this document). Table at the end of this chapter lists the
specifications for the GX-3R.
About the GX-3R
Using an advanced detection system consisting of up to three gas sensors, the GX-3R personal
four-gas monitor detects the presence of combustible gas, oxygen (O2), carbon monoxide
(CO), and hydrogen sulfide (H2S) simultaneously. The GX-3R’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 GX-3R offers a full
range of features, including:
• Simultaneous monitoring of one to four gases
• 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 readings
• Built-in time function
• Lunch break feature
• CSA “C/US” classified as intrinsically safe (see Table 2 on page 8)
WARNING: The Model GX-3R detects oxygen deficiency, elevated levels of oxygen,
combustible gases, carbon monoxide, and hydrogen sulfide, all of which
can be dangerous or life threatening. When using the GX-3R, 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 GX-3R as described in this
manual.

8 • Chapter 1: Introduction GX-3R Operator’s Manual
Specifications
Table 1: Standard Sensor Specifications/Alarm Points
Combustible Gas, Methane (CH4)
Calibration Standard*
Oxygen (O2) Hydrogen
Sulfide (H2S)
Carbon
Monoxide (CO)
Detection Range 0 - 100% LEL 0 - 40% volume 0 - 200.0 ppm 0 - 2000 ppm
Lowest Detectable
Limit (LDL) n/a n/a 0.5 ppm 3 ppm
Reading Increment 1% LEL 0.1% volume 0.1 ppm 1 ppm
Warning
Setpoint
10% LEL 19.5% volume,
decreasing
5.0 ppm 25 ppm
Alarm
Setpoint
25% LEL 18.0% volume,
decreasing
30.0 ppm 50 ppm
Alarm H
Setpoint
50% LEL 23.5% volume,
increasing
100.0 ppm 1200 ppm
STEL Setpoint n/a n/a 5.0 ppm 200 ppm
TWA Setpoint n/a n/a 1.0 ppm 25 ppm
Indication Accuracy • Continuous environment (-20°C to
50°C): ± 5% of reading or ± 2%
LEL (whichever is greater)
• Temporary environment (-40°C to
-21°C and 51°C to 60°C): ± 10%
LEL
• 0 - 25.0%:
± 0.5% O2
• 25.1 - 40.0%:
± 3.0% O2
• 0 - 100 ppm: ± 5% of
reading or ± 2 ppm
H2S (whichever is
greater)
• 101 - 200 ppm:
± 20% of reading
• 0 - 500 ppm: ± 5%
of reading or
±5ppmCO
(whichever is
greater)
• 501 - 2000 ppm:
± 20% of reading
* The GX-3R is also available set up for general hydrocarbons and calibrated to a combustible gas other than methane, such as isobutane. Con-
sult RKI Instruments, Inc. for further information.
Table 2: GX-3R Specifications
Sampling
Method
Diffusion
Response Time T90 within 30 seconds
Display Graphics LCD Display
Environmental
Conditions
• 3000 meter maximum altitude
• Operating pressure: 70 - 120 kPa (70 - 110 kPa for explosion proof)
• Pollution degree 2
•IP66/68
Operating
Temperature &
Humidity
Continuous environment: -20°C to 50°C/Below 90% RH
Temporary environment (up to 15 minutes): -40°C to 60°C/Below 95% RH

GX-3R Operator’s Manual Chapter 1: Introduction • 9
Safety/
Regulatory
• ATEX: Certificate Number: DEKRA 17ATEX0103 X
II1G Ex da ia IIC T4 Ga/IM1 Ex da ia I Ma (with NCR-6309)
II1G Ex ia IIC T4 Ga/IM1 Ex ia I Ma (without NCR-6309)
• IECEx: Certificate Number: IECEx DEK 17.0050X
Ex da ia IIC T4 Ga/Ex da ia I Ma (with NCR-6309)
Ex ia IIC T4 Ga/Ex ia I Ma (without NCR-6309)
• CSA classified, “C/US”, as Intrinsically Safe. Class I Division 1 Groups A, B, C, D T4.
Class I, Zones 0, A/Ex da ia IIC T4 Ga (with NCR-6309)
Class I, Zones 0, A/Ex ia IIC T4 Ga (without NCR-6309)
C US
186718
Power Supply Lithium ion battery pack (3.7 VDC, 200 mA)
Continuous
Operating
Hours
@ 25 °C
With combustible gas sensor: 25 hours in Measuring Mode (non-alarm operation)
Without combustible gas sensor: 60 hours in Measuring Mode (non-alarm operation)
Battery
Charger Ratings
Input: 100 - 240 VAC, 47 - 63 Hz, 2.4 A
Output: 5.99 VDC, 2A max
Case High-impact Plastic, RF Shielded, Dust and Weather Proof (IP66/68)
Included
Accessories
• Alligator clip
• Rubber boot
• Wrist strap
• Calibration cup
• Single-unit charger
Other
Accessories
• 12 VDC adapter
• Multi-unit charger
• Belt clip
•SDM-3R
•RP-3R
• Aspirator adapter
• IrDA/USB Cable for connecting to a computer when using the Data Logger Management
Program (not needed if computer has an infrared port)
Dimensions and
Weight
Approximately 65(H) x 58(W) x 26(D) mm (2.6”H x 2.3”W x 1.0”D)
Approximately 100 g (3.5 oz.)
Table 2: GX-3R Specifications

10 • Chapter 1: Introduction GX-3R Operator’s Manual
About this Manual
The GX-3R Operator’s Manual uses the following conventions for notes, cautions, and
warnings.
NOTE: Describes additional or critical information.
CAUTION: Describes potential damage to equipment.
WARNING: Describes potential danger that can result in injury or death.

GX-3R Operator’s Manual Chapter 2: Description • 11
Chapter 2: Description
Overview
This chapter describes the GX-3R instrument and its accessories.
Instrument Description
Case
The GX-3R’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 on the front of the case allows for LCD viewing. The black
bottom cover, located on the bottom of the case, allows access to the filters and sensors. A
sensor retainer and filter gasket help orient and retain the sensor and filters.
Three threaded inserts on the back of the case allow for installation of an alligator clip or belt
clip.
LCD
The digital LCD (liquid crystal display) simultaneously shows the gas reading for all installed
sensors. The LCD also shows information for each of the GX-3R’s operating modes.
WARNING: A thin protective film covers the display to prevent scratches during
shipping. Remove this film before use. Leaving the film installed voids the
intrinsically safe certification.
GX-3R
POWER
MODE
CO/H2SLELO2
AIR
Bottom
Cover
Charging
Socket
Sensor
Retainer
Buzzer
Opening Front Back
LCDLEDs
Threaded
Inserts
Figure 1: Component Location

12 • Chapter 2: Description GX-3R Operator’s Manual
Control Buttons
Two control buttons, AIR and POWER MODE, are located below the LCD.
Alarm LEDs
The six alarm LEDs around the edge of the case 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, low
battery voltage, and as an indicator during use of the GX-3R’s many display and adjustment
options.
Vibrator
A vibrating motor inside the GX-3R case vibrates for gas alarms, unit malfunctions, and as an
indicator during normal use of the various modes of the GX-3R.
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 “Stealth and Vibrator Settings
(STEALTH)” on page 115.
Table 3: GX-3R Control Button Functions
Button Function(s)
AIR • turns on LCD backlight
• resets alarm condition if LATCHING is set to ON in Maintenance Mode
• enters User Mode, Maintenance Mode, and Gas Select Mode when used
with POWER MODE button
• activates the demand zero function (adjusts the GX-3R’s fresh air reading)
• changes the value of a parameter available for adjustment
• scrolls through parameter options
POWER MODE • turns the GX-3R on and off
• turns on LCD backlight
• enters and scrolls through Display Mode
• enters instructions into the GX-3R’s microprocessor
• resets alarm condition if LATCHING is set to ON in Maintenance Mode
• enters User Mode, Maintenance Mode, and Gas Select Mode when used
with AIR button

GX-3R Operator’s Manual Chapter 2: Description • 13
Sensors
The GX-3R uses three sensors to monitor combustible gas, oxygen (O2), carbon monoxide
(CO), and hydrogen sulfide (H2S) simultaneously. The sensors are located inside the GX-3R
and are held in their sockets by the sensor retainer and bottom cover. The sensors use different
detection principles, as described below.
Combustible Gas Sensor
The combustible gas sensor detects combustible gas in the % LEL range using 2 catalytic
elements: a standard element and a poison-resistant element that is resistant to sensor poisons
like silicone. The element’s resistance changes based on the reaction of gas with oxygen. The
change in resistance affects the current flowing through the element. The GX-3R’s circuitry
amplifies the current, converts the current to a gas concentration, and displays the
concentration on the LCD.
The standard calibration for the combustible gas sensor is to methane but the sensor will still
detect and respond to a variety of combustible gases.
O2/CO/H2S Sensors
The O2, CO, and H2S sensors are electrochemical cells that consist 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 GX-3R’s circuitry amplifies the
current, converts the current to a gas concentration, and displays the concentration on the
LCD.
There are 4 different types of CO and H2S sensors available:
• CO only (ESR-A13P-CO): A single electrochemical cell that detects CO. Instruments
with this sensor cannot detect H2S.
•H
2compensated CO (ESR-A1CP-CO-H): A single electrochemical cell that detects CO.
This sensor does not respond to or responds minimally to hydrogen (displays H2 RICH
once H2concentration reaches 2000 ppm). Instruments with this sensor cannot detect H2S.
•H
2S only (ESR-A13i-H2S): A single electrochemical cell that detects H2S. Instruments
with this sensor cannot detect CO.
•CO/H
2S (ESR-A1DR-COHS): A combination electrochemical cell that detects both CO
and H2S.
Dummy Sensors
A dummy sensor is installed in any units that have less than 3 sensors. Dummy sensors are
factory installed. The flat side of the dummy sensor faces away from the GX-3R and the
hollow side faces toward the GX-3R.
Filters
Combustible Gas Sensor H2S Removal Filter Disk (Dark Red)
An H2S removal filter disk is placed into a recess in the filter gasket over the combustible gas
sensor. The filter disk prolongs the life of the combustible gas sensor by preventing H2S in the
ambient air from reaching the sensor. The H2S filter disk is dark red in color and although it
may darken over time, its color is not indicative of remaining filter life.
The H2S filter disk needs replacing once it’s been exposed to 33 ppm hours of H2S. This
means the filter needs replacing after 80 minutes of exposure to 25 ppm H2S which equates to
40 2-minute calibrations with a cylinder containing 25 ppm H2S. If H2S exists in the
monitoring environment, the H2S filter disk will have to be replaced more frequently.

14 • Chapter 2: Description GX-3R Operator’s Manual
CO/H2S Sensor Dual Filter (Black and White)
A dual filter is placed into a recess in the filter gasket over the dual CO/H2S sensor. The black
half is a charcoal filter for the CO sensor. The white half is a humidity filter for the H2S
sensor.
Replace the filter if you notice:
• Unexplained CO readings.
• For users with a 1 ppm H2S alarm setpoint: A drift on the H2S zero reading,
unexplained H2S readings, the filter appears dirty, or every 6 months (whichever is
sooner).
CO Sensor 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 H2S and certain hydrocarbons out of the sample to avoid false CO
readings. If false or elevated CO readings are noticed, especially in the presence of H2S,
change the charcoal filter.
H2S Sensor Humidity Filter (White)
A white humidity filter covers the H2S sensor. The filter absorbs humidity in the sampling
environment to prevent unstable readings around 0 ppm H2S. For users with a 1 ppm H2S
alarm setpoint, the filter should be replaced every 6 months, if you notice a drift on the zero
reading, or if the filter appears dirty (whichever is sooner). For users with a 2 ppm or higher
H2S setpoint, the filter does not necessarily need to be replaced.
Hydrophobic Dust Filter
The oval-shaped hydrophobic dust filter is attached to the top of the filter gasket, covering the
sensor ports and the filters. The filter gasket and hydrophobic dust filter get replaced as a set.
NOTE: Some GX-3Rs have a hydrophobic dust filter that is not attached to the filter gasket.
When replacing the hydrophobic dust filter on one of these GX-3Rs, remove the
filter and the gasket and replace it with a filter gasket/hydrophobic dust filter
assembly.
Infrared Communications Port
An infrared (IR) communications port is located on the top of the case, near the top 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 GX-3R
Data Logger Management Program. See the GX-3R Data Logger Management Program
operator’s manual for data logging and downloading instructions.
Charging Socket and Battery Pack
A charging socket on the back of the instrument allows for charging cable connection.
A lithium ion (Li-ion) battery pack powers the GX-3R. At 25°C the battery lasts at least 25
hours. The battery icon in the upper right of the LCD shows remaining battery life.
A low battery warning activates when the GX-3R detects a low battery voltage. The GX-3R
sounds a dead battery alarm when battery voltage is too low for Measuring Mode.
The battery pack can be recharged by using the GX-3R charging cable. The battery pack is not
user-replaceable.

GX-3R Operator’s Manual Chapter 2: Description • 15
NOTE: Use of batteries or battery chargers not specified by RKI Instruments, Inc. will
compromise the CSA classification and may void the warranty. See “Recharging
the Batteries” on page 83.
WARNING: To prevent ignition of a hazardous atmosphere, batteries must only be
changed or charged in an area known to be nonhazardous.
AVERTISSEMENT:Pour éviter l’inflammation d’une atmosphère dangereuse, les batteries
doivent uniquement être modifiés ou facturés dans une zone connue
comme non dangereuse.
Included Accessories
Alligator Clip
An alligator clip is installed on the back of the GX-3R. The alligator clip can be used to attach
the GX-3R to clothing or a belt. Teeth in the alligator clip’s jaws prevent the unit from
slipping off.
Rubber Boot
A black rubber boot is installed on the GX-3R.
Wrist Strap
A wrist strap is included with the GX-3R and can be attached to the wrist strap installation
feature on the left side of the GX-3R’s case.
Alligator Clip
Figure 2: Alligator Clip

16 • Chapter 2: Description GX-3R Operator’s Manual
Single-Unit AC Charger
The charging cable is a 4 foot cable with an AC adapter on one end and a charging plug that
connects to the GX-3R on the other end.
Calibration Cup
Use the calibration cup to apply gas during a bump test, calibration, or gas test. The
calibration cup has an installation orientation to observe. “Front” and “rear” imprinting on the
bottom of the cup correspond to the front and rear of the GX-3R when the calibration cup is
installed. In addition, a “front” label on the front of the calibration cup should be visible when
viewing the LCD with the calibration cup installed.
Other Accessories
12 VDC Charger
The 12 VDC charger is a 4 foot cable with a vehicle plug on one end and plug that connects to
the GX-3R’s power jack on the other end.
Multi-Unit AC Charger
The multi-unit charger is a 4 foot wall plug style adapter that plugs into a bar. The bar has five
2-foot cables coming out one side. The end of each of the five cables has a plug that connects
to the GX-3R’s power jack. The AC adapter is rated 100 - 240 VAC input, 5.99 VDC output.
Figure 3: Charging Cable
AC Adapter
Charging
Plug
Figure 4: Calibration Cup
FRONT

GX-3R Operator’s Manual Chapter 2: Description • 17
Belt Clip
A belt clip makes it easy to hook the GX-3R to a utility belt.
SDM-3R
The SDM-3R is a calibration station for the GX-3R and GX-3R Pro. The station’s buttons can
be used for operations (Standalone Mode) or a computer can be used to control the docking
station (PC Controlled Mode). See the appropriate SDM-3R manual for more information.
RP-3R
The RP-3R is a pump that draws sample to the GX-3R. See the RP-3R manual for more
information.
Aspirator Adapter
The aspirator adapter is a squeeze-bulb assembly that draws sample to the GX-3R.
IrDA Cable
Unless your computer has a built-in IrDA port, an IrDA cable is needed to establish
communication between the GX-3R and the Datalogging Program or the User Setup Program.
Belt Clip
Figure 5: Belt Clip

18 • Chapter 3: Operation GX-3R Operator’s Manual
Chapter 3: Operation
Overview
This chapter explains how to use the GX-3R to perform confined space entry monitoring or
general area monitoring in Measuring Mode.
Start Up
This section explains how to start up the GX-3R, get it ready for operation, and turn it off.
WARNING: A thin protective film covers the display to prevent scratches during
shipping. Remove this film before use. Leaving the film installed voids the
intrinsically safe certification.
NOTE: The screens illustrated in this section are for a standard 4-gas unit. The screens
displayed by your GX-3R may be slightly different.
Turning On the GX-3R
To illustrate certain functions, the following description of the GX-3R start up sequence
assumes that the following menu items in User Mode are turned on: LUNCH, CAL RMDR,
and BUMP.RMDR in User Mode, and ID DISP and AUTOZERO in Maintenance Mode. If
any of these items are turned off, then the corresponding screens will not appear.
1 . Press and briefly hold down POWER MODE. Confirm that the LCD turns on, the LEDs
flash, the buzzer sounds, and the motor vibrates before continuing with operation.
Release the POWER MODE button when you hear a beep.
2 . If LUNCH is set to ON (factory setting if OFF, see “Updating the Lunch Break Setting
(LUNCH)” on page 74), 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 GX-3R 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 GX-3R is turned on.
b. Reset Accumulation: To reset the accumulation of peak and time-weighted average
(TWA) readings, press and release AIR before the countdown reaches 0.
RESUME
7:49
SEC
5

GX-3R Operator’s Manual Chapter 3: Operation • 19
3 . If CAL RMDR is set to ON (factory setting) and a calibration is due, the screen that
appears next depends on how CAL EXPD is set in User Mode (see “CAL EXPD” on
page 67). The three possible screens are described below. If a calibration is not due, the
instrument shows how many days are left until a calibration is due.
CAL EXPD set to
CONFIRM (factory setting)
CAL EXPD set to
CANT USE
CAL EXPD set to
NONE
LCD
Sound Buzzer sounds double pulsing tone Buzzer sounds double pulsing
tone
None
Action • Option A, Perform calibration:
Press and release POWER
MODE to perform a calibration.
The instrument takes you
straight to the AUTO CAL CYL
A screen in User Mode’s GAS
CAL\AUTO CAL item. If
Password Protection is set to
On using the SDM-3R PC
program, you must enter a
password. See pg.56 for
calibration instructions.
If the calibration is successful,
the screen above will not appear
again until the unit is due for
calibration. If the calibration is
not successful, the screen above
will again appear in the startup
sequence.
• Option B, Bypass message: To
continue without performing a
calibration, press and release
AIR.
The GX-3R cannot be used until a
successful calibration is per-
formed. Press and release
POWER MODE to perform a cali-
bration. The instrument takes you
straight to the AUTO CAL CYL A
screen in User Mode’s GAS
CAL\AUTO CAL item. If Pass-
word Protection is set to On
using the SDM-3R PC program,
you must enter a password. If you
don’t press POWER MODE, the
instrument automatically goes to
the AUTO CAL CYL A screen
after 6 seconds. If Password Pro-
tection is set to On using the
SDM-3R PC program, you must
enter a password. See pg.56 for
calibration instructions.
If the calibration is successful, the
screen above will not appear again
until the unit is due for calibration.
If the calibration is not successful,
the screen above will again appear
in the startup sequence.
• Option A, Perform calibration:
To perform a calibration, press
and release POWER MODE.
The instrument takes you
straight to the AUTO CAL
CYL A screen in User Mode’s
GAS CAL\AUTO CAL item. If
Password Protection is set to
On using the SDM-3R PC
program, you must enter a
password.
• Option B, Bypass message: To
continue without performing a
calibration, wait a few seconds
for the instrument to continue
with its startup sequence.
CAL--LMT
7:49
CAL
CAL--LMT
7:49
FAIL
NEXT CAL
7:49
0 d

20 • Chapter 3: Operation GX-3R Operator’s Manual
4 . If BUMP.RMDR is set to ON (factory setting is OFF) and a bump test is due, the screen
that appears next depends on how BUMP.EXPD is set in User Mode (see
“BUMP.EXPD” on page 71). The three possible screens are described below. If a bump
test is not due, the instrument shows how many days are left until a bump test is due.
5 . The Date/Time Screen appears for a few seconds.
BUMP.EXPD set to
CONFIRM (factory setting)
BUMP.EXPD set to
CANT USE
BUMP.EXPD set to
NONE
LCD
Sound Buzzer sounds double pulsing
tone
Buzzer sounds double pulsing tone None
Action • Option A, Perform bump test:
Press and release POWER
MODE to perform a bump test.
The instrument takes you
straight to the BUMP CYL A
screen in User Mode’s BUMP
item. If Password Protection
is set to On using the SDM-3R
PC program, you must enter a
password. See page 49 for
bump test instructions.
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: To
continue without performing a
bump test, press and release
AIR.
The GX-3R cannot be used until a
successful bump test has been per-
formed. Press and release POWER
MODE to perform a bump test.
The instrument takes you straight
to the BUMP CYL A screen in
User Mode’s BUMP item. If
Password Protection is set to On
using the SDM-3R PC program,
you must enter a password. If you
don’t press POWER MODE, the
instrument automatically goes to
the BUMP CYL A screen after 6
seconds. If Password Protection
is set to On using the SDM-3R PC
program, you must enter a pass-
word. See page 49 for bump test
instructions.
If the bump test is successful, the
screen above will not appear again
until the unit is due for bump test-
ing. If the bump test is not success-
ful, the screen above will again
appear in the startup sequence.
• Option A, Perform bump test:
To perform a bump test, press
and release POWER MODE.
The instrument takes you
straight to the BUMP CYL A
screen in User Mode’s BUMP
item. If Password Protection
is set to On using the SDM-3R
PC program, you must enter a
password.
• Option B, Bypass message: To
continue without performing a
bump test, wait a few seconds
for the instrument to continue
with its startup sequence.
BUMP--LMT
7:49
CAL
BUMP--LMT
7:49
FAIL
NEXT BP
7:49
0 d
7:49
7:49
18 - 12.22