RKI Instruments GX-86A User manual

INSTRUCTION MANUAL
MODEL GX-86A
PORTABLE FOUR GAS DETECTOR
RKI Instruments, Inc.
33248 Central Ave, Union City, CA 94587 • Tel: [phone]

Model GX-86A Instruction Manual
RKI Instruments, Inc. Page 1
INTRODUCTION
The RKI Model GX-86A is an advanced gas detection instrument,
incorporating proven detection hardware and microprocessor controls.
The GX-86A is compact, convenient, and offers a full range of
features, including:
•Simultaneous detection of combustible gas, oxygen deficiency,
carbon monoxide, and hydrogen sulfide. (Other toxic gases
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-86 acces-
sories
WARNING
THE GX-86A IS DESIGNED TO DETECT COMBUSTIBLE
GAS, OXYGEN DEFICIENCY, HYDROGEN SULFIDE, AND
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.

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DESCRIPTION
The RKI Model GX-86A detects combustible gas (LEL), oxygen
deficiency (O2), carbon monoxide (CO), and 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-86A 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. See Figure 1.
The GX-86A 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
Combustible 0 - 100% LEL (lower
explosive limit)
O20 - 40%
H2S 0 - 100 ppm (parts per mil-
lion)
CO 0 - 300 ppm

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RKI Instruments, Inc. Page 3
Control Panel
Battery Cover
Remote Alarm/
Charger Jack
Jack
Sensor
Cover
Internal
Buzzer Interface
Port
Figure 1. GX-86A Components
Earphone

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COMPONENTS AND CONTROLS
Case
The GX-86A 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-86A. The switches are touch-
pads, to reduce the possibility of accidental activation or damage. See
Figure 2.
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.
OFF - HOLD 5 SEC
PPM
% LEL % PPM
AIR ▼
(SHIFT)
▲DISPLAY
/(ADJ.) ON/OFF
/ENTER
Figure 2. Contr
ol Panel

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2. AIR/▲
TheAIR/▲switch activates the GX-86A’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-86A’s microprocessor.
4. DISPLAY/(ADJ)
The DISPLAY/(ADJ) switch activates the display modes, and
enters instructions into the GX-86A’s microprocessor.
5. Alarm LEDs
Four red light-emitting diodes (LEDs) provide visual alarms for
gas concentrations and malfunctions.
Battery Compartment
The GX-86A uses two “C” size cells; alkaline batteries will run the
GX-86A for approximately 10 hours, rechargeable nickel-cadmium
batteries will run for approximately 7 hours. (Rechargeable batteries
can be recharged in the GX-86A with the optional battery charger.)
The GX-86A battery compartment is located on the back of the
instrument. The battery cover has a strap to prevent accidental
opening.
Interface Port
The GX-86A’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

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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. An
identical jack on the bottom right rear corner connects to an external
buzzer or the optional battery charger.
Carrying Case
The carrying case has openings for the diffusion grill, buzzer, remote
alarm/charger jack, earphone 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

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RKI Instruments, Inc. Page 7
atmosphere to diffuse inward. See Figure 3.
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-86A into a reading of gas concentration.
The LEL sensor responds to a wide range of gases; see Appendix A
for the Relative Response Chart.
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-86A into an
oxygen reading.
CO, and H2S (Toxics) Sensors
The toxics sensors are electrochemical cells, which react to gas in the
CO Sensor
O2Sensor
H2S Sensor
LEL Sensor
Sensor Cover
Spring Clips (2)
Figure 3. Sensors

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atmosphere, producing a current proportional to the concentration of
gas. The current is converted by the GX-86A 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.

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RKI Instruments, Inc. Page 9
OPERATION
Preparation
Normally the GX-86A requires little preparation before use. To install
the GX-86 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-86A. 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