RKI Instruments GX-82 User Manual

Instruction Manual

Model GX-82

Portable Three Gas Monitor

Part Number: 71-0000RK
Edition: Second
Released: November 1997

RKI Instruments, Inc. • 33248 Central Ave. Union City, CA 94587 • [phone]

Warranty

RKI Instruments, Inc., warranties gas alarm equipment manufactured by RKI and sold by
RKI to be free from defects in materials and workmanship for a period of one year from
date of shipment from RKI Instruments, Inc. Any parts found defective within that period
will be repaired or replaced, at our option, free of charge. This warranty does not apply to
items that are subject to deterioration or consumption in normal service, and which must
be cleaned, repaired, or replaced routinely. Those items include, but are not limited to:

absorbent cartridges filter elements
pump diaphragms and valves batteries
lamp bulbs and fuses

This warranty is voided by mechanical damage, misuse, alteration, rough handling, or
repairs not in accordance with the operator’s manual. This warranty indicates the full
extent of our liability. We are not responsible for removal or replacement costs, local repair
costs, transportation costs, or contingent expenses incurred without our prior approval.

THIS WARRANTY IS IN LIEU OF ANY OTHER WARRANTIES AND REPRESENTATIONS,

EXPRESSED OR IMPLIED, AND ALL OTHER OBLIGATIONS OR LIABILITIES ON THE PART OF RKI

INSTRUMENTS, INC., INCLUDING BUT NOT LIMITED TO THE WARRANTY OF

MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL RKI

INSTRUMENTS, INC., BE LIABLE FOR INDIRECT, INCIDENTAL, OR CONSEQUENTIAL LOSS OR

DAMAGE OF ANY KIND CONNECTED WITH THE USE OF ITS PRODUCTS OR FAILURE OF ITS
PRODUCTS TO FUNCTION OR OPERATE PROPERLY.

This warranty covers instruments and parts sold to end users by authorized distributors,
dealers, and representatives of RKI Instruments, Inc.

We do not assume indemnification for any accident or damage caused by the operation of
this gas monitor. Our warranty is limited to replacement of parts or our complete goods.

ii • Warranty Model GX-82 Operator’s Manual

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Components and Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Case. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Control Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Buzzers and Earphone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Battery Compartment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Circuit Boards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Start-up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Normal Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Safety Self-Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Emergency Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Supplies and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Calibrating the GX-82. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Calibration with the RKI Four-Gas Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

CO Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Sensor Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Sensor Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Extender Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Sample-draw Aspirator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Sample-draw Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Appendix A: Parts List. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Appendix B: RKI Model GX-82 Relative Response Chart . . . . . . . . . . . . . . . . . . . . . . . . 17

Model GX-82 Operator’s Manual Table of Contents • iii

iv Model GX-82 Operator’s Manual

Introduction

The RKI Model GX-82 is a proven gas detection instrument, in use internationally for
personal protection in a wide variety of industries. The GX-82 is compact, convenient, and
offers a full range of features, including:

Description

• simultaneous detection of combustible gas (%LEL), oxygen deficiency (O
carbon monoxide (CO), or hydrogen sulfide (H

S)

2

), and

2

• dot-matrix display for complete, understandable information at a glance

• distinctive audible alarms for dangerous conditions and malfunctions

• intrinsic safety for Class I, Division I, Group C and D hazardous atmospheres

• microprocessor control for reliability, ease of use, and advanced capabilities

• small size and light weight for user comfort

WARNING: The GX-82 is designed to detect combustible gas, oxygen deficiency, and

hydrogen sulfide or carbon monoxide, which can be life threatening. Users
must follow the instructions and warnings in this manual to assure proper
and safe operation of the GX-82.

The RKI Model GX-82 is an advanced portable instrument for simultaneous detection of
combustible gas (LEL), oxygen deficiency (O

sulfide (H

S). See Table 1 for detection ranges. Gas detection features include distinctive

2

), and carbon monoxide (CO) or hydrogen

2

alarms for dangerous gas concentrations and time-weighted averaging for exposure to
toxic gases (CO or H

S).

2

The GX-82 is compact enough to be worn on a belt loop or shoulder strap, which leaves
your hands free. It has a tough plastic housing, touch-pad control panel, back-lit display,
and comes with a vinyl carrying case.

The GX-82 is easy to adjust and maintain. The batteries and diffusion sensors are user­replaceable. The GX-82 also displays battery condition and sensor malfunction during
start-up and operation.

Table 1: Ranges of Target Gases

Gas Detected Range

Combustible

0 to 100% LEL

1

Oxygen 0 to 40%
Hydrogen sulfide

0 to 100 ppm

2

Carbon monoxide 0 to 300 ppm

1

LEL (Lower Explosive Limit)

2

ppm (Parts Per Million)

Model GX-82 Instruction Manual Introduction • 1

Components and Controls

This section describes the GX-82’s components and user controls.

Case

The GX-82 has a rigid plastic case that is durable and shock-resistant. The sensors are
housed in a metal diffusion head at the bottom of the GX-82. The touch-pad control panel
and display are located on the top. The carrying case has openings for the diffusion grill,
buzzer, remote alarm, earphone jack, and control panel. The case includes a belt loop and
shoulder strap loops.

Sensors

The sensors are mounted in the diffusion head at the bottom of the GX-82. The diffusion
grill protects the sensors. The grill easily snaps off the instrument case so you can
conveniently replace the sensors.

Combustible gas sensor

The combustible gas (LEL) sensor is contained in a metal cylindrical shell, with a bayonet­pin base for easy replacement. The perforations at the end of the shell allow atmosphere to
diffuse into the sensor.

Combustible gas sensor - principle of operation

The LEL sensor is a platinum-coated resistive element, with a non-catalytic, electrically
identical reference element, to compensate for temperature variations and other
environmental factors. The elements are housed in a sintered stainless steel flame arr estor
that permits the atmosphere to diffuse inward but prevents flame to pass outward when
an explosive atmosphere is encountered. The two elements form half of a balanced
Wheatstone Bridge. When voltage is applied to the elements, combustible gas in the
atmosphere catalyzes on the platinum coating, raising the temperature and changing the
resistance of the element, causing an imbalance in the Wheatstone Bridge. The imbalance
is measured by the GX-82’s circuitry and converted to a measurement of gas
concentration.

Oxygen sensor

The oxygen (O
for easy replacement. The shell forms one electrical contact, and a button on the base is the

other contact. The perforations at the end of the shell allow atmosphere to diffuse into the
sensor.

Oxygen sensor - principle of operation

The O
alkaline electrolyte. A fluorocarbon membrane covers the cell and allows atmosphere to

diffuse into the electrolyte at a rate proportional to the partial pressure of oxygen. The
oxygen reacts in the cell, producing a current pr oportional to the concentration of oxygen.
The current develops a voltage across a temperature-compensating thermistor/resistor
network. The voltage is measured by the circuitry of the GX-82 and converted to a
measurement of gas concentration.

sensor is an electrochemical cell. It consists of gold and lead electrodes in an

2

) sensor is contained in a cylindrical metal shell, with a bayonet pin base

2

2 • Components and Controls Model GX-82 Instruction Manual

S.

CO and H

The CO and H

S sensor

2

S sensors are physically identical, except for their external labels. The

2

sensors are housed in a cylindrical plastic shell, with a bayonet-pin base for easy
replacement. The perforations at the end of the shell allow atmosphere to diffuse into the
sensor. The CO sensor also has a slip-on charcoal filter that covers the diffusion end. The
filter eliminates interference from H

CO and H

The CO and H

S sensor - principle of operation

2

S sensors are electrochemical cells, consisting of two precious metal

2

2

electrodes in an acid electrolyte. A gas permeable membrane covers the cell and allows
gas in the atmosphere to diffuse into the electrolyte at a rate proportional to its partial
pressure. The gas reacts in the cell, producing a current proportional to the concentration
of gas. The current is amplified by the circuitry of the GX-82 and converted to a
measurement of gas concentration. To maintain sensitivity and stability, the CO and H

S

2

sensors are exposed to a continuous bias current, even when the power is off.

Control Panel

The control panel is at the top of the GX-82 for easy access when you carry the GX-82. The
control panel contains the display, alarm lights, and buttons that control the many
functions of the GX-82. The buttons are touch-pads to reduce the possibility of accidental
activation or damage.

Table 2: GX-82 Button Functions

Button Function

POWER ON/OFF The POWER ON/OFF button controls power to the GX-82.

(Bias power for the electrochemical sensors is not affected by
the POWER button.)

BATT/DOSE The BATT/DOSE button displays the battery voltage and

the average level of H

S and CO exposure since the last time

2

the GX-82 was started.

PEAK HOLD The PEAK/HOLD button displays the highest reading for

exposure to LEL and H
O

exposure. It is also used (with the BATT/DOSE button)

2

S or CO, and the lowest reading for

2

to activate the GX-82’s Auto Zero function.
(All measurements are tracked since the last time the GX-82

was turned on.)

Alarm Lights Red light-emitting diodes (LEDs) labeled COMB, OXY, H

2

or CO flash when the alarm for that gas is activated. The
alarm light automatically resets when the conditions fall
below (or rise above for O

) the alarm levels.

2

S,

Model GX-82 Instruction Manual Components and Controls • 3