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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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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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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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

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c.This message shows to verify that the data logger circuits are set
properly for accurate data collection according to date and time.
d.These messages show while the GX-86A checks itself for
proper operation. If a malfunction occurs, the display will alert
the user. (The display shows “HC” [hydrocarbons] for the
%LEL reading.)
d.The normal operating display shows after the “OK” message,
showing fresh-air concentrations for all gases. The GX-86A
sounds a double tone to indicate the instrument is in normal
operation.
2. Verify Operation
To easily verify correct operation of the GX-86A, breathe out over
the diffusion grill of the instrument. The O2 reading should drop
measurably before returning to normal.
To verify detection of combustibles use a controlled source of
flammable vapor, for example a bottle of isopropyl alcohol. The
DATE / TIME
MMM DD YY 00:00
SELF DIAGNOSIS
10 SECONDS TO GO
HC O2 H2S CO
STANDBY
HC O2 H2S CO
OK

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audible alarm will sound, the ALARM LED will blink, and the
HC will flash on the display.

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Caution
Do not use gas from a cigarette lighter to test response to
combustibles. Exposing the sensor to uncontrolled high
concentrations of gas in this manner will reduce
response and sensor life.
WARNING
IFTHE GX-86A DOES NOT RESPOND TO THESE VERIFICA-
TIONS, TAKE IT TO AKNOWN “FRESH-AIR” ENVIRON-
MENT, THEN FOLLOW THE DEMAND ZERO PROCEDURE
DESCRIBED IN ADJUSTMENT AND CALIBRATION. REPEAT
THE VERIFY OPERATION PROCEDURE BEFORE USING THE
GX-86A IN APOTENTIALLY HAZARDOUS LOCATION.
Normal Operation
The GX-86A will continuously monitor the atmosphere, and display
the LEL, O2, and toxic gas concentrations present. If the GX-86A is
taken into a low-light environment, the display backlight will
automatically turn on. To use with sample-drawing attachments, insert
the probe into the area to be monitored and wait a few seconds for
response.

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DISPLAY FUNCTIONS
While the GX-86A is in normal operation, press the DISPLAY/(ADJ.)
switch to step through the measurement functions. The display will
hold for 20 seconds before reverting to normal detection, or until
DISPLAY/(ADJ.) is pressed to go to the next screen.
User and Station ID
This screen appears only when the user ID option is activated. (See
USER OPTIONS.) Use this screen to verify user, location, or other
programmed information.
To change User and Station ID:
1. At the User and Station ID screen, press ON/OFF/ENTER.
2. The first character (left end) on “U ID” will flash. Press AIR or
SHIFT to scroll through 0 - 9, A - Z to select the desired character.
3. Press ON/OFF/ENTER to enter that value and move to the next
character.
4. Repeat steps 1. and 2. until the desired User and Station IDs are
entered.
Peak
The Peak function shows the highest (lowest for O2) concentrations
detected since the GX-86A was turned on. Peak readings (indicated
by “P” at the left side of the display) stay in the instrument’s memory
U ID:0123456789
S ID:ABCDEFGHIJ

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until a higher level is detected, the data logger is cleared, or the unit is
turned off.
Average
The Average function shows the average gas concentrations (indicated
by “A” at the left side of the display) detected since the last time the
GX-86A was turned on or the data logger was cleared.
Elapsed Time
The Elapsed Time function shows the time in minutes since the
memory was cleared or the instrument was turned on. This allows the
user to easily track total time over multiple monitoring sessions.
Short-Term Exposure Limit (STL)
The STL function shows the average reading for toxic gases during
the last 15 minutes.
HC O2 H2S CO
P45 19.5 10.5 210
HC O2 H2S CO
A18 20.8 2.5 100
TIME (OPERATION)
XXX MINUTES
(STL) H2S CO
PPM XX.X XXX

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Time-Weighted Average (TWA)
The TWA function shows the average reading for toxic gases during
the last 8 hours. If 8 hours has not elapsed since the last time the
STEL/TWA was cleared, the average is still calculated over 8 hours,
with the missing time assigned a 0 value for readings.
Battery Voltage
The Battery Voltage function shows the minimum operating voltage
and present battery voltage.
Note
The GX-86A automatically checks battery voltage during
start-up; if the measurement is below 2.3V, the GX-86A will
not operate.
Date / Time
This function shows the current time, date, and ambient temperature,
for example:
(TWA) H2S CO
PPM XX.X XXX
BATTERY MIN. 2.3V
BATTERY NOW 3.0V
DATE / TIME
Apr 8 95 14:23

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Clear Data Logger
The Clear Data Logger function allows the user to reset the data
logger storage to accept a new set of data. Clearing the Data Logger
also resets the Peak, Average, Time in Operation, STL, TWA, and
Log. Time readings. This function shows three displays. Press AIR/▲
to continue through this function, or DISPLAY/(ADJ.) to skip to the
next function.
Log. Time
The Log. Time function shows the time left on the data collection
program. The duration depends upon the frequency of sampling. Press
DISPLAY/(ADJ.) once more to return to the normal operating display.
ARE YOU SURE?
YES:AIR NO:DISP
CLEARED
OK
CLEAR DATALOGGER?
YES: AIR NO: DISP
LOG. TIME: XXX
HOURS REMAINING

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ALARMS
Alarm Indications
1. Combustibles (%LEL)
If the combustible gas detected exceeds the first level alarm setting
(20% LEL for most applications), a pulsed tone will sound, the
%LEL LED will blink, and the “HC” on the display will flash.
If the combustible gas detected rises above the high alarm setting
(50% LEL for most applications), the alarm tone and LED will be
continuous.
2. Oxygen
If the oxygen content of the air drops below the low alarm setting
(usually 19.5%), a pulsed tone will sound, the % LED will blink,
and the “O2” on the display will flash.
If the oxygen content of the air rises above the high alarm setting
(usually 22.5%), the alarm tone and LED will be continuous.
3. H2S
If the H2S detected exceeds the alarm setting (usually 10 ppm), a
pulsed tone will sound, the PPM LED above the H2S reading will
blink, and the “H2S” on the display will flash.
4. CO
If the CO detected exceeds the alarm setting (usually 25 ppm), a
pulsed tone will sound, the PPM LED above the CO reading will
blink, and the “CO” on the display will flash.

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5. STEL (toxics only)
If the average toxic gas level detected over the last 15 minutes
exceeds the STL, an alarm will sound and the message “STL” will
show on the display in the field for that gas.
6. TWA (toxics only)
If the average toxic gas level detected over the last 8 hours exceeds
the TWA, an alarm will sound and the message “TWA” will show
on the display in the field for that gas.
7. CLG (toxics only)
If toxic gas detected exceeds the ceiling level, the alarm tone and
LED will be continuous, and the display will alternate between
“CLG” and the name of that gas.
8. If the full scale reading is exceeded for any channel, the alarm
tone and LED will be continuous. The display will show “MAX”
in the field for that gas.
Resetting Alarms
The GX-86A can be set for latching or self-resetting logic. Latching
alarms can not be reset until the gas concentration falls below the
alarm point. When the condition is corrected, press DISPLAY to reset
the alarm. Self-resetting alarms will automatically shut off when the
concentration falls below the alarm point. (See USER OPTIONS.)
Malfunction Alarm and Emergency Operation
The GX-86A continuously monitors itself for proper operation. If a
malfunction occurs, a single steady “trouble” tone will sound, and one
of the following messages will show on the display:

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1. Sensor failure
If any sensor fails during operation, the display will show the
failed sensor in parentheses (CO sensor in this example):
To continue using the GX-86A, turn it off, then follow the
appropriate start-up sequence. During start-up the display will
show the failed channel before the count down. In normal
operation display will indicate the failed sensor as “xx or xx.x.”
Low Battery Alarm
When the battery charge drops near the lower limit, the display will
show the first screen below, with the “B” flashing. When the charge
drops to the limit, the second screen will show, with the “CHANGE
BATTERY” flashing, the buzzer will sound continuously, and the GX-
86A can not be used to monitor gas concentrations:
SELF DIAGNOSIS
FAIL( CO)
HC O2 H2S CO
0 20.9 00.0 xxx
HC O2 H2S CO
B 0 20.9 00.0 0
HC O2 H2S CO
CHANGE BATTERY