RKI Instruments GX-82A User manual

INSTRUCTION MANUAL
MODEL GX-82A
PORTABLE THREE GAS DETECTOR
RKI Instruments, Inc.
33248 Central Ave. Union City CA 94587 • Tel: [phone]

Model GX-82A Instruction Manual
062796 RKI Instruments, Inc. Table of Contents
Table of Contents
INTRODUCTION 1
DESCRIPTION 2
COMPONENTS AND CONTROLS 3
Case 3
Control Panel 3
Switches 3
Battery Compartment 4
Interface Port 4
Buzzers and Earphone 5
Carrying Case 5
Sensors 5
Combustible Gas Sensor 5
Oxygen Sensor 6
CO, or H2S (toxic gas) Sensor 6
OPERATION 7
Preparation 7
Standard Start-up 7
Normal Operation 9
DISPLAY FUNCTIONS 10
User and Station ID 10
Peak 10
Average 11
Elapsed Time 11
Short-Term Exposure Limit (STL) 11
Time-Weighted Average (TWA) 12
Battery Voltage 12
Date / Time 12
Clear Data Logger 13
Log. Time 13
ALARMS 14
Alarm Indications 14
Resetting Alarms 15
Malfunction Alarm and Emergency Operation 16
Low Battery Alarm 17
CALIBRATION 18
Calibration Supplies and Equipment 18
Demand Zero and Calibration Preparation 18
Calibration Start-up 19
Auto Calibration 20
Combustibles Span 22
Oxygen Zero 23
H2S and CO Span 24

Model GX-82A Instruction Manual
Table of Contents Hayward, California [phone]
MAINTENANCE 25
Batteries 25
Sensor Maintenance 26
Combustibles Sensor 26
O2Sensor 27
Toxics Sensors 27
Sensor Replacement 27
CO Filter 28
ACCESSORIES 29
Extender Cable 29
Sample-Drawing Pump 29
Manually-Operated Sample-Drawing Aspirator 30
USER OPTIONS 32
Entering Programming Mode 32
General Programming Hints 32
WARRANTY 37

Model GX-82A Instruction Manual
062796 RKI Instruments, Inc. 1
INTRODUCTION
The RKI Model GX-82A is an advanced gas detection instrument,
incorporating proven detection hardware and microprocessor controls.
The GX-82A is compact, convenient, and offers a full range of
features, including:
•Simultaneous detection of combustible gas, oxygen deficiency, and
carbon monoxide or hydrogen sulfide (detection for other toxic
gases is optional)
• Dot-matrix liquid crystal display (LCD) for complete, understand-
able information at a glance
• Distinctive audible alarms for dangerous conditions and malfunc-
tions
•Intrinsic safety for Class I, Division I, Groups A, B, C, and D haz-
ardous atmospheres
•Microprocessor control for reliability, ease of use, and advanced
capabilities, including data logging and user-adjustable alarms
•Convenient size, with the full range of well-known GX-82 acces-
sories
WARNING
THE GX-82A IS DESIGNED TO DETECT COMBUSTIBLE
GAS, OXYGEN DEFICIENCY, AND HYDROGEN SULFIDE OR
CARBON MONOXIDE, WHICH CAN BE LETHAL. USERS
MUST FOLLOW THE INSTRUCTIONS AND WARNINGS IN
THIS MANUAL TO ASSURE PROPER AND SAFE OPERATION
OF THE INSTRUMENT.

Model GX-82A Instruction Manual
2 Hayward, California [phone]
DESCRIPTION
The RKI Model GX-82A detects combustible gas (LEL), oxygen
deficiency (O2), and carbon monoxide (CO) or hydrogen sulfide
(H2S). See Table 1 for standard detection ranges for these gases. Gas
detection features include distinctive alarms for dangerous gas
concentrations, time-weighted averaging and short term exposure
limit for toxic gases, and logging of detection data.
The GX-82A has a rugged plastic housing, touch-pad control panel,
and a back-lit dot matrix LCD. The included carrying case protects the
instrument and allows hands-free operation for the user.
The GX-82A is easy to adjust and maintain, with user-replaceable
batteries and sensors. The microprocessor control enables the user to
display a comprehensive listing of gas levels detected and other
related data.
Table 1: Standard Detection Ranges
Gas
Detected Range
Combusti-
ble 0 - 100% LEL (lower explosive limit)
O20 - 40%
H2S 0 - 100 ppm (parts per mil-
lion)
CO 0 - 500 ppm

Model GX-82A Instruction Manual
062796 RKI Instruments, Inc. 3
COMPONENTS AND CONTROLS
Case
The GX-82A has a durable plastic case. The sensors are housed in a
detachable block at the bottom of the instrument.
Control Panel
The control panel contains the display, alarm lights, and switches that
control the many functions of the GX-82A. The switches are touch-
pads, to reduce the possibility of accidental activation or damage. See
Figure 1.
Switches
1. ON/OFF/ENTER
The ON/OFF/ENTER switch controls power to the instrument.
(Bias power for the electrochemical sensors is not affected by the
power switch.) It also selects input modes to access user-
changeable features.
Figure 1. Contr
ol Panel
% LEL % PPM
AIR▲▼
(SHIFT) DISPLAY
/(ADJ.) ON/OFF
/ENTER
OFF - HOLD 5 SEC

Model GX-82A Instruction Manual
4 Hayward, California [phone]
2. AIR/▲
TheAIR/▲switch activates the GX-82A’s Demand Zero function,
which automatically adjusts the instrument in fresh-air conditions.
It is also used to scroll through the display and settings modes.
3. (SHIFT)/▼
The (SHIFT)/▼switch scrolls through the display and settings
modes, and enters instructions into the GX-82A’s microprocessor.
4. DISPLAY/(ADJ)
The DISPLAY/(ADJ) switch activates the display modes, and
enters instructions into the GX-82A’s microprocessor.
5. Alarm LEDs
Three red light-emitting diodes (LEDs) provide visual alarms for
gas concentrations and malfunctions.
Battery Compartment
The GX-82A uses two “C” size cells; alkaline batteries will run the
GX-82A for approximately 10 hours, rechargeable nickel-cadmium
batteries will run for approximately 7 hours. (Rechargeable batteries
can be recharged in the GX-82A with the optional battery charger.)
The GX-82A battery compartment is located on the back of the
instrument. The battery cover has a strap to prevent accidental
opening.
Interface Port
The GX-82A’s built-in data logger records gas concentrations at
programmed intervals. These measurements can be downloaded
through the interface port to a PC-compatible computer for use in data

Model GX-82A Instruction Manual
062796 RKI Instruments, Inc. 5
analysis programs.
Buzzers and Earphone
An electronic buzzer is mounted at the back of the case, behind a felt
screen. The buzzer sounds for gas alarms and system malfunctions.
A 2.5 mm phone jack at the bottom left rear corner of the case
connects to an earphone, for use in high noise environments, and the
battery charger.
Carrying Case
The carrying case has openings for the diffusion grill, buzzer,
earphone/charger jack, control panel, and Data Logger interface port.
The carrying case includes a belt loop and shoulder straps.
Sensors
The sensors are mounted at the rear of the instrument, in a removable
block. A slotted metal cover protects the sensors, but allows
atmosphere to diffuse inward.
Combustible Gas Sensor
The LEL sensor detects combustible gas and vapors in the atmosphere
with a catalytic platinum element. The reaction of gas with oxygen on
the catalyst causes a change in the resistance of the element, which is
converted by the GX-82A into a reading of gas concentration.

Model GX-82A Instruction Manual
6 Hayward, California [phone]
Oxygen Sensor
The O2sensor is an electrochemical cell, which reacts to the oxygen
in the atmosphere, producing a current proportional to the oxygen
concentration. This current is converted by the GX-82A into an
oxygen reading.
CO, or H2S (toxic gas) Sensor
The toxic gas sensor is an electrochemical cell, which reacts to gas in
the atmosphere, producing a current proportional to the concentration
of gas. The current is converted by the GX-82A into a measurement of
gas concentration. The CO sensor uses a charcoal filter disk that
covers its opening, to eliminate interference from H2S.
To maintain sensitivity and stability, these sensors are kept on a
continuous bias current, even when the instrument power is off.
Batteries with an adequate charge must be installed to provide the bias
current.

Model GX-82A Instruction Manual
062796 RKI Instruments, Inc. 7
OPERATION
Preparation
Normally the GX-82A requires little preparation before use. To install
the GX-82A Extender Cable, see the ACCESSORIES section.
Standard Start-up
1. Press the ON/OFF/ENTER switch once.
a.This message shows only when the “Lunchbreak” feature is
activated (See USER OPTIONS). Press the AIR/▲switch to
continue Short Term Exposure Limit (STL) and Time-Weighted
Average readings from the last use of the GX-82A. Press DISP/
(ADJ.) to start new STL and TWA readings
Lunchbreak can accumulate up to 100 hours of STL/TWA read-
ings. If the 100-hour limit is exceeded, this prompt appears:
Press AIR/▲to clear the memory and start accumulation of
readings.
b.The start-up battery check shows the minimum usable and
actual battery voltage (for example, 3.0V for fresh batteries).
STL TWA RESUME
YES:AIR NO:DISP
CANT RESUME
PUSH AIR: CLEAR
BATTERY MIN. 2.3V
BATTERY NOW 3.0V