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

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

062796 RKI Instruments, Inc. Table of Contents

Model GX-82A Instruction Manual

MAINTENANCE 25

Batteries 25
Sensor Maintenance 26
Combustibles Sensor 26
O2 Sensor 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

Table of Contents Hayward, California [phone]

Model GX-82A Instruction Manual

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, understand­able information at a glance

• Distinctive audible alarms for dangerous conditions and malfunc­tions

• Intrinsic safety for Class I, Division I, Groups A, B, C, and D haz­ardous 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 acces­sories

WARNING

THE GX-82A IS DESIGNED TO DETECT COMBUSTIBLE

GAS

, OXYGEN DEFICIENCY, AND HYDROGEN SULFIDE OR

CARBON

MONOXIDE, WHICH CAN BE LETHAL. USERS

MUST
THIS
OF

062796 RKI Instruments, Inc. 1

FOLLOW THE INSTRUCTIONS AND WARNINGS IN

MANUAL TO ASSURE PROPER AND SAFE OPERATION

THE INSTRUMENT.

Model GX-82A Instruction Manual

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.

Table 1: Standard Detection Ranges

Gas

Range

Detected

Combusti-

ble

O

2

0 - 100% LEL (lower

explosive limit)

0 - 40%

H2S 0 - 100 ppm (parts per mil-

lion)

CO 0 - 500 ppm

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.

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Model GX-82A Instruction Manual

ol Panel

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 touch­pads, to reduce the possibility of accidental activation or damage. See
Figure 1.

% LEL %

AIR

▲

(SHIFT)

▼

DISPLAY

/(ADJ.)

PPM

ON/OFF
/ENTER

OFF - HOLD 5 SEC

Figure 1. Contr

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 user­changeable features.

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Model GX-82A Instruction Manual

2. AIR/▲

The AIR/▲ 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

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Model GX-82A Instruction Manual

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.

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Model GX-82A Instruction Manual

Oxygen Sensor

The O2 sensor 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.

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Model GX-82A Instruction Manual

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

STL TWA RESUME

YES:AIR NO:DISP

Lunchbreak can accumulate up to 100 hours of STL/TWA read­ings. If the 100-hour limit is exceeded, this prompt appears:

CANT RESUME

PUSH AIR: CLEAR

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).

BATTERY MIN. 2.3V
BATTERY NOW 3.0V

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Model GX-82A Instruction Manual

c.This message shows to verify that the data logger circuits are set

properly for accurate data collection according to date and time.

DATE / TIME

MMM DD YY 00:00

Note

The display illustrations in this manual show only “H2S.” If
your instrument detects CO or another toxic gas, informa­tion for that gas will appear in the H2S section of the dis­play.

d.These messages show while the GX-82A checks itself for

proper operation. If a malfunction occurs, the display will alert
the user. (The display shows “HC” [hydrocarbons] for the
%LEL reading.)

SELF DIAGNOSIS

10 SECONDS TO GO

HC O2 H2S

STANDBY

d.The normal operating display shows after the “OK” message,

showing fresh-air concentrations for all gases. The GX-82A
sounds a double tone to indicate the instrument is in normal

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operation.

Model GX-82A Instruction Manual

HC O2 H2S

OK

062796 RKI Instruments, Inc. 9

Model GX-82A Instruction Manual

2. Verify Operation

To easily verify correct operation of the GX-82A, 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
audible alarm will sound, the %LEL will blink, and the HC will
flash on the display.

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

IF THE GX-82A DOES NOT RESPOND TO THESE VERIFICA-

TIONS
MENT
DESCRIBED
THE

, TAKE IT TO A KNOWN “FRESH-AIR” ENVIRON-

, THEN FOLLOW THE DEMAND ZERO PROCEDURE

IN ADJUSTMENT AND CALIBRATION. REPEAT

VERIFY OPERATION PROCEDURE BEFORE USING THE

GX-82A IN A POTENTIALLY HAZARDOUS LOCATION.

Normal Operation

The GX-82A will continuously monitor the atmosphere, and display
the LEL, O2, and toxic gas concentrations present. If the GX-82A 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

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