GX-94 Operator’s Manual Part Number: 71-0008RK Edition: Revision P2 Released: 6/10/2002 RKI Instruments, Inc. 33248 Central Ave.
WARRANTY RKI Instruments, Inc., warrants the GX-94 sold by us to be free from defects in materials, workmanship, and performance for a period of one year from the date of shipment from RKI Instruments, Inc. Any parts found defective that warranty period will be repaired or replaced, at our option, free of charge. This warranty does not apply to those items which by their nature are subject to deterioration or consumption in normal service, and which must be cleaned, repaired, or replaced on a routine basis.
TABLE OF CONTENTS INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Battery Compartment . . . . . . . . . . . . . . . . . . .
SETUP MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tips for Using Setup Mode. . . . . . . . . . . . . . . . . . . . . . . . . Entering Setup Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Resetting the NVRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . Updating the Gas Combination . . . . . . . . . . . . . . . . . . . . . Viewing and Setting Alarms . . . . . . . . . . . . . . . . . . . . . . . . Setting the Serial Number . . . . . . . . . . . . . .
INTRODUCTION The RKI Model GX-94 is an advanced gas detection instrument in use internationally for personal protection in a variety of industries. The GX94 is rugged, compact, convenient, and offers a full range of features, including: • Simultaneous detection of two, three, or four gases. The standard configuration is combustible gas in the %LEL range (HC,) oxygen deficiency (O2), carbon monoxide (CO), and hydrogen sulfide (H2S).
SPECIFICATIONS Table1 lists physical and environmental specifications for the GX-94. Table 2 lists specifications for the GX-94’s sensors and channels. Table 1: GX-94 Specifications Target Gases Combustible Gas (HC); Oxygen (O2), Carbon Monoxide (CO), Hydrogen Sulfide (H2S) Case RFI Shielded High Impact ABS Plastic Safety/Regulatory UL Classified Instrinsically Safe for Class I, Division I, Groups A, B, C, & D Dimensions 3.54” x 2.52” x 6.
Table 2: Sensor/Channel Specifications Combustible Gas (HC) Oxygen Hydrogen Sulfide Carbon Monoxide Detection Range 0 - 100% LEL 0 - 40.0% 0 - 100.0 ppm 0 - 500 ppm Display Increments 1% LEL 0.1% 0.5 ppm 1 ppm Low Alarm1 10% LEL 19.5% (decreasing) 10.0 ppm 25 ppm High Alarm1 50% LEL 23.5% (increasing) ---- ---- TWA Alarm1 ---- ---- 10.0 ppm 25 ppm STEL Alarm1 ---- ---- 15.
DESCRIPTION Case The GX-94 has a high impact, RF shielded ABS plastic case with a rubber guard that also functions as a water-resistant seal between the two halves of the case. The case has sturdy plastic flanges on the left and right sides for installation of the shoulder strap. It has an opening on the top front of the GX-94 for the buzzer sound and it has sensor ports which allow diffusion through the sensor screen on the top rear of the GX-94.
GX-94 is carried or clipped on a belt. It contains the display, the touchpad buttons that control the many functions of the GX-94, the Alarm LED, and the light sensor. The display is to the left of the buttons and simultaneously shows the gas readings for all active channels. The touch-pad buttons are low profile to reduce the risk of accidental activation and damage. The functions of the control panel buttons are described below in Table 3.
easy viewing of the display, the light sensor prompts the display backlight to turn on. Note The backlight does not operate in Setup Mode. Sensor Screen Belt Clip Bottom Case Threaded Hole for Sample Adapter Top Case Battery Cover Screw Battery Cover Buzzer Opening Interface Port Cover Shoulder Strap Flange, 2X Figure 2: Top & Side views of the GX-94 Battery Compartment The battery compartment is located on the top of the GX-94. A tethered battery cover allows easy battery replacement.
The GX-94 uses two “C” size cells. Alkaline batteries will run the GX-94 for approximately 12 hours of non-alarm operation. Rechargeable nickel-cadmium batteries will run it for approximately 8 hours of nonalarm operation. The GX-94 does not include a charging jack, so rechargeable batteries must be removed from the GX-94 and charged separately. See the Parts List at the end of this manual for available bench top battery chargers.
diffusion screen and scrubs out H2S and most hydrocarbons which cause a response on the CO sensor. Sensors The sensors are located inside the case in the top rear of the GX-94 behind the diffusion ports. A rubber sensor gasket is installed over the sensors and forms a seal between the sensors and the inside of the case to prevent any moisture or dirt which may enter the diffusion ports from entering the inside of the GX-94.
labels. The toxic sensor is housed in a cylindrical plastic shell with four connection pins at the base for easy replacement. The membrane covered diffusion opening at the top of the shell allows atmosphere to diffuse into the sensor. The toxic sensors are electrochemical cells, which react to gas in the atmosphere, producing a current proportional to the concentration of gas. The current is converted by the GX-94’s circuitry into a measurement of gas concentration.
OPERATION The GX-94 has four operating modes: normal operation mode, display mode, setup mode, and calibration mode. This section describes the GX-94 in normal operation mode. It includes procedures to start up and shut down the GX-94. Note The screens illustrated in this section are of a four gas GX94. If you have a two gas or a three gas GX-94, some of your screens will look slightly different. Preparation Normally the GX-94 requires little preparation before use.
turned off.) The Battery Voltage Screen displays. Press DISPLAY/(ADJ.) to reset these measurements. The Battery Voltage screen displays. If you do not press the AIR/▲ or DISPLAY/(ADJ.) buttons within 5 seconds, the GX-94 automatically resumes the TWA, peak, and average readings and continues accumulating the time in operation from the last session. The Battery Voltage screen displays. The Battery Voltage screen displays the minimum usable and actual battery voltage.
When the GX-94 successfully completes its self check, the OK message displays instead of the STAND BY message, then the normal operating screen displays. The normal screen displays current concentrations for all gases. The GX-94 sounds a double tone to indicate it is in normal operation. HC 0 LEL O2 20.9% H2S 0.0PPM CO 0PPM 2. Verify that the GX-94 is operating properly. Breathe out over the diffusion grill of the instrument until the oxygen reading drops below the low alarm level.
DEMAND ZERO PROCEDURE DESCRIBED IN THE CALIBRATION SECTION. REPEAT THE VERIFY OPERATION PROCEDURE DESCRIBED ABOVE BEFORE USING THE GX-94 IN A POTENTIALLY HAZARDOUS LOCATION. Normal Operation The GX-94 will continuously monitor the ambient air and display the target gas concentrations present. If the GX-94 is taken into a low-light environment, the display backlight will automatically turn on.
ALARMS Alarm Indications 1. Combustibles (HC) Low and High Alarm If the combustible gas detected exceeds the low alarm setting, a pulsed tone will sound, the alarm LED will blink, and the display will flash “HC.” If the combustible gas detected rises above the high alarm setting, the alarm tone and alarm LED will be continuous. 2. Oxygen Low and High Alarm If the oxygen content of the air drops below the low alarm setting, a pulsed tone will sound, the alarm LED will blink, and the display will flash “O2.
and the message “TWA” will alternate with the gas name on the display in the field for that gas. 6. Ceiling (CLG) Alarm, H2S and CO Only If H2S or CO detected exceeds the ceiling alarm setting, the audible alarm and LED will be on continuously, and the display will alternate between “CLG” and the gas name on the display in the field for that gas. Note The CLG alarm is set to OFF as shipped from RKI Instruments. It is user adjustable.
When the charge drops to the lower limit, the following screen displays: BATTERY MIN. 2.3V CHANGE BATTERY Low Battery Alarm The buzzer and alarm LED are on steadily and the “CHANGE BATTERY” message flashes. The GX-94 is not operational as a gas monitoring device when the unit is in low battery alarm 10. Sensor Failure and Emergency Operation. The GX-94 continuously monitors itself for proper operation. If a malfunction occurs, the GX-94 alerts you with audible and visual alarms.
To continue using the GX-94, turn it off, then follow the start-up sequence. During start-up, the Fail screen will display and the buzzer and alarm LED will pulse momentarily. When the normal operation screen comes up, the display will indicate the failed sensor as “xxx”: HC O2 H2S CO xxxLEL 20.9% 0.0PPM 0PPM Resetting Alarms The GX-94 can be set for latching or self-resetting alarms (see Setting the Alarm Logic in the Setup Mode section).
DISPLAY MODE The GX-94 has four operating modes: normal operation, display mode, setup mode, and calibration mode.
USER ID ******** STATION ID ******** To enter or update a User and Station ID, press ON/OFF/INPUT. The first character under USER ID will flash (* is default). Press AIR/▲ or SHIFT/▼ to scroll through the alphabet (A-Z) and numbers (0-9). When the correct character shows, press ON/OFF/INPUT to go to the next character. After the correct information is entered, press DISPLAY/ (ADJ) to exit this screen.
Average Screen The Average function shows the average gas concentrations detected since the unit was turned on. The average readings are calculated using the logged readings which are saved at the frequency set in the 6. Set Time Interval menu item in the setup mode. When selected at startup, the Lunch Break RESUME option enables the GX-94 to continue calculating the average reading from the last operating session. A V G . 0LEL 20.9% 0.
Short-Term Exposure Limit (STEL) Screen The STEL function shows the average reading for H2S and CO during the last 15 minutes. These values are not affected by the Lunch Break function and are reset every time the unit is turned off. STEL H2S CO 0.0PPM 0PPM Time-Weighted Average (TWA) Screen The TWA function shows the average reading for toxic gases during the last 8 hours.
Battery Voltage Screen The Battery Voltage function shows the minimum operating voltage and current battery voltage. New alkaline batteries typically measure 3.0 V; fully charged Ni-Cd batteries typically measure 2.6V. BATTERY MIN. 2.3V BATTERY NOW 2.8V Note The GX-94 automatically checks battery voltage during startup; if the measurement is below 2.3V, the GX-94 will not operate.
Clear Data Logger Screens The Clear Data Logger screens allow the user to clear the data logger memory. This function shows three screens. Press AIR/▲ to continue through this function, or DISPLAY/(ADJ.) to skip to the next function. CLEAR DATA LOGGER ? YES: AIR NO: DISP ARE YOU SURE ? YES: AIR NO: DISP CLEARED OK If the data logger memory is cleared, the Remaining Log Time will be reset, and all collected data will be erased.
SETUP MODE The advanced microprocessor program in the GX-94 allows the user to select and adjust many of the detection and data logging features.
AIR/▲ and (SHIFT)/▼ buttons. Entering Setup Mode 1. Take the GX-94 to a fresh air location—the instrument does not detect gas while in setup mode. 2. If it is not already off, turn the GX-94 off. 3. Hold down the AIR/▲ and (SHIFT)/▼ buttons simultaneously, then press ON/OFF/INPUT. The main menu will appear (release the buttons at this time). The “1” will be flashing indicating the cursor position and that this item is currently selected. 1.SET DEF NVRAM 2.COMBINE GAS 4.
Updating the Gas Combination (2. COMBINE GAS) Sets the display and circuitry for types of gases to be detected; there are 11 possible combinations. Press AIR/▲ or (SHIFT)/▼ to scroll through the combinations. Press ON/OFF/INPUT to accept the selected combination. Note Change the GAS COMBINATION values only when the appropriate sensors are installed in the corresponding sensor sockets. Calibrate immediately after changing sensor combinations.
oxygen levels and the HIGH O2 alarm is an increasing alarm, for rising oxygen levels. • SET ALARM Allows the user to change the LOW, TWA, STEL, and CLG (ceiling) alarms for H2S. • SET ALARM Allows the user to change the LOW, TWA, STEL, and CLG (ceiling) alarms for CO. Setting the Serial Number (4. SET SERIAL No.) Sets or updates the instrument serial number. 1. At the SERIAL No. screen, the first character (left end) will flash.
Setting the Data Logging Frequency (6. SET TIME INTERVAL) Sets the time between the logging of the instantaneous readings for the Data Logger. Hold down the AIR/▲ or (SHIFT)/▼ switch to scroll rapidly through the values. The time interval may be set from 5 seconds to 300 seconds (5 minutes). Setting the Alarm Logic (7. SET LATCHING) Toggles alarm logic between self-resetting (default) and latching alarms by turning latching ON or OFF.
to scroll rapidly through values. Setting the Data Logging Alarm (11. SET LOG ALARM) When the Data Logger memory capacity has been filled to the percentage selected here, the GX-94 alerts you. Default setting is off, with a range of 1 - 100%. Tip: hold AIR/▲ or (SHIFT)/▼ to scroll rapidly through values. Setting the Buzzer Frequency (12. SET TONE) Sets the frequency of the alarm buzzer in the range 1969 - 2153 Hz.
CALIBRATION MODE Calibration mode allows you to calibrate the GX-94’s sensor response. It also includes a menu item which allows you to set the date and time. Calibrate the GX-94 when you replace a sensor. Also calibrate the GX94 periodically to assure proper sensor response. The frequency of calibration depends upon the amount and type of use. Determine you own calibration frequency taking your application and requirements into account. A typical calibration frequency is once per month.
with the fixed flow regulator and RKI Four Gas Cylinder. It also includes instructions for calibration with individual gas sources. Preparation 1. Take the GX-94 to a non-hazardous location with fresh-air conditions. 2. Turn on the instrument and allow one minute to warm up. 3. Perform a demand zero. Press and hold the AIR/▲ button on the control panel until. The instrument will indicate on the display that it is adjusting the zero settings.
The GX-94’s calibration menu includes two methods of calibration: auto calibration or single calibration. • Auto Calibration: This method allows you to calibrate all four sensors simultaneously. It is designed for use with the RKI Four gas Calibration Cylinder and is the quickest and easiest method to calibrate the GX-94. • Single Calibration: This method allows you to calibrate one sensor at a time.
one or more concentrations do not match, continue with step 4. 4. To adjust the values on this screen, hold down the (SHIFT)/▼ button and press the DISPLAY/(ADJ.) button. The AUTO CAL. value screen for the combustible gas channel displays. AUTO CAL. 50 LEL 5. Use the AIR/▲ (increase) and (SHIFT)/▼ (decrease) buttons to set the correct combustible gas value. 6. Press the ON/OFF/INPUT button to enter the new setting. The AUTO CAL. value screen for the next channel displays. 7.
calibrate. The other sensors calibrate normally. The buzzer and alarm LED activate. Press the AIR/▼ button to reset the alarm and return to the main menu. Replace the failed sensor(s), then repeat calibration. 11. AUTO CAL END displays, then the Calibration menu displays. 12. Unscrew the regulator from the cylinder. 13. Remove the adapter plate from the GX-94. 14. Press the SHIFT/▼ button to place the prompt next the 7.RETURN menu option, then press the ON/OFF/INPUT button to return to normal operation.
2. Press the ON/OFF/INPUT button to display the HC CAL. screen. The gas reading is flashing HC CAL. 0 LEL APPLY/GAS/ ADJ/INPUT 2. Screw the regulator onto the cylinder. The gas begins to flow. Note The combustible gas sensor is a general hydrocarbon sensor that responds to most flammable gases; the response will vary depending upon the substance. For best results, calibrate the GX-94 to the target gas. 3. Allow the gas to flow for one minute.
reads “OXYGEN ZERO”. Verify the concentration of oxygen listed on the cylinder’s label and set the zero reading to the same concentration. A 100% nitrogen source (0% oxygen) is recommended when using single calibration. 7. After the last channel is calibrated, press the (SHIFT)/▼ button until the number 7 in front of RETURN, the last menu item, flashes. 8. Press the ON/OFF/INPUT button to return to normal operation. Setting the Date and Time The number 6 option in the calibration menu is SET DATE/TIME.
NOTE The time is displayed in military format, a 24 hour clock instead of a 12 hour clock. 5. After the minutes are entered, press ON/OFF/INPUT to return to the main menu. 6. Press (SHIFT)/▼ to scroll to the last menu item, 7 RETURN. 7. Press ON/OFF/INPUT to return to normal operation.
MAINTENANCE Main Batteries 1. Check the battery voltage periodically by pressing the DISPLAY button to reach the Battery Voltage Screen. Replace the batteries before the voltage drops to the operational limit (see Alarms, Low Battery). WARNING TAKE THE GX-94 TO A NON-HAZARDOUS LOCATION BEFORE REPLACING THE BATTERIES. 2. To replace the batteries, unscrew the battery compartment cover retaining screw and remove the cover.
Lithium Memory Backup Battery The memory backup battery is a 3.0 volt lithium battery which protects against loss of the GX-94’s memory when the main batteries are dead or removed. The memory backup battery typically lasts for 5 years. Replace the memory backup battery every 5 years or if you notice that the GX-94 is losing logged data when the main batteries are changed. Memory Backup Lithium Battery GX-94 Shown w/out Top Case Figure 3: Lithium Backup Battery 1.
6. Install a fresh battery in the battery holder. Use a CR2032 3.0 volt coin type lithium battery. See the Parts List at the end of this manual for a replacement battery available from RKI Instruments, Inc. 7. Reinstall the cover, belt clip, and screws. Charcoal Filter The CO sensor diffusion opening is equipped with an activated carbon filter disk that includes an integral rubber boot. It removes H2S and most hydrocarbons to limit interference with the CO measurement.
2. Remove the diffusion screen. 3. Remove the old charcoal filter w/rubber boot from the CO sensor diffusion port. Place the new filter in the filter slot. Replace the filter when CO readings become suspect (e.g., CO circuit calibrates properly, but shows response in a known CO-free environment), or when replacing sensor, whichever comes first. 4. Replace the diffusion screen. 5. Replace the diffusion screen retaining screw.
Toxics Sensors Replace the sensor when: 1. The detection circuit cannot be calibrated correctly. 2. The display does not show 00 immediately after the start-up sequence and cannot be set to zero by the Demand Zero command. Note Allow up to 1/2 hour after the toxics sensors have been replaced to show a normal response, then calibrate.
1. Take the GX-94 to a non-hazardous location and turn the power off. 2. Remove the four (4) Phillips screws from the bottom of the instrument. (Two in the belt clip and two next to the label.) 3. Pull the top and bottom case apart where the rubber cushion covers the seam. This opens the entire case. 4. Remove the sensor gasket from the sensors. 5. To replace individual sensors, gently unplug from the circuit board by pulling straight up. 6. Carefully insert a new sensor.
ACCESSORIES Sample-Drawing Pump The GX-94 Sample-Drawing pump converts the GX-94 into a portable sample drawing system. The pump is easy to install and use, and is built to give years of dependable service. Installing the Pump 1. Slide the pump onto the sensor end of the GX-94, as shown in Figure 6. Probe Hose, 10 ft Standard Pump Retaining Screw GX-94 Pump Pump On/Off Switch Pump Battery Cover Screw Figure 6: Attaching the GX-94 Pump 2.
inserts into the threaded hole in the sensor screen, then tighten it to connect the pump and the instrument. 3. Connect the sample hose and probe to the pump inlet. Using the GX-94 with the Pump 1. Turn on the GX-94 and slide the pump power switch to the ON position. Verify that the pump is running (low humming sound). 2. After the GX-94 has completed normal start-up, place the probe tip in the area to be monitored.
Pump Maintenance 1. Replace the pump battery when the pump won’t start or can’t maintain flow adequate to keep the Low Flow alarm off. a. Loosen the battery cover screw on the end of the pump to remove the battery cover. b. Replace the old battery with a “C” size alkaline or fully charged Ni-Cad battery. c. Replace the battery cover. 2. Inspect the cotton filter in the probe handle periodically.
PARTS LIST Table 4 lists replacement parts and accessories for the GX-94.
Table 4: Parts List Part Number Description 80-0009RK-10 Hose,10 ft., polyurethane, for use with pump or aspirator adapter 80-0150RK Probe, for use with pump or aspirator adapter 81-1169RK GX-94 pump adapter with 10 ft.
