INSTRUCTION MANUAL RKI INSTRUMENTS, INC. MODELS: OX-94, CO-94, HS-94 PORTABLE SINGLE GAS MONITORS RKI Instruments, Inc. 33248 Central Ave.
INTRODUCTION The RKI Models OX-94, CO-94, and HS-94 (the 94 series) are compact portable gas detection instruments. They are designed to protect the worker from dangerous gas levels, and are also intended to be used as survey tools to determine gas levels in a workspace or other confined space. These instruments offer a full range of features, including: • Continuous detection of one of three hazards.
The 94 series instruments are very compact to easily fit in a shirt pocket or on a belt. It also comes equipped with a lanyard which can be used to hang the instrument from the users shoulder or to wear around ones neck. The 94 series also comes equipped with a vinyl carrying case for added protection and durability. The 94 series is housed in a rugged water resistant plastic housing, and has a touch pad control panel with two pushbuttons from which all functions can be accessed.
Oxygen Sensor The oxygen sensor is an electrochemical cell, consisting of gold and lead electrodes in an 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 proportional to the concentration of oxygen. The current develops a voltage across a temperature-compensating thermistor/resistor network.
CIRCUIT BOARDS The GX-82 has two circuit boards; the main board, and the sensor/buzzer board. The main board contains the electronics and the display. The sensor/buzzer board contains only the sensor and buzzer, and connects to the main board with a ribbon cable. OPERATION 1. Start Up A. Press and hold the POWER switch for two seconds. The buzzer will sound a single tone, and the display will activate all of its digits and symbols. B.
WARNING If the Instrument does not respond to these verifications, take it to a known “fresh-air” environment, then follow the zero and calibration procedures in this manual. Repeat the Verify Operation procedure before using the Instrument in a potentially hazardous location. 3. Normal Operation The 94 Series Instrument will continuously monitor the atmosphere, display the O2, H2S, or CO concentrations present, and sound alarm if a dangerous level is encountered. A.
Note The 94 series automatically checks battery voltage during start-up; if the measurement is below 2.1V, the instrument will not operate. During normal operation, when the battery voltage drops to 2.0V, the battery sign will blink on the display, a continuous alarm tone will sound, and the display will show a blinking battery. WARNING The instrument does not monitor the atmosphere during a dead battery alarm.
4. Auto Zero/Span To automatically adjust the zero point for H2S or CO, (or the span to 20.9% for oxygen), take the instrument to a known fresh-air environment. With instrument in normal operation, press and hold the AIR button. The unit will beep three times, and then give a double beep indicating that it has adjusted to the surrounding atmosphere. 5. Alarms Gas Level Alarms The 94 Series instruments have standard alarm points as listed below: OX-94 19.5% decreasing, 23.
SENSOR FAIL This alarm will sound if the sensor is missing or has an internal open connection. This type of alarm is indicated by the steady audible tone, and with a large “X” appearing on the display upper left. To resolve, verify that there is a sensor in the instrument, or, replace the sensor if necessary. CALIBRATION AND MAINTENANCE The 94 series microprocessor circuit allow the instrument to be calibrated and zeroed completely with the external buttons. There are no internal user adjustments.
2. While continuing to hold the AIR Button, press also the MODE button until instrument beeps. 3. After the beep, release the MODE button but continue to hold the AIR button for a few seconds until the display completes warmup and reads the gas concentration. Just to the left of the gas reading there will be a small arrow pointing downward. This indicates that the instrument is ready to set the zero reading. Zeroing the instrument: 4. Apply the zero gas.
30 or 60 (for H2S) or 150 (for CO). Once you have scrolled to the value of your calibration gas, go to step 9. 9. Press the MODE switch, and the instrument should read the gas levels in the surrounding air. Now apply the span gas to the instrument using an appropriate test cup to fit over the sensor area. Allow sufficient time for full response (30 to 60 seconds). 10. Press the AIR switch and hold for 5 beeps.
• O2 Sensor Replace the O2 sensor when: 1. The O2 circuit cannot be set to 0 on an oxygen-free sample. 2. The OXY (O2) display does not show 20.9% immediately after the start-up sequence and after the Auto Zero command (AIR adjust). 3. The O2 reading tends to drift with instrument position. • H2S and CO Sensors Replace the sensor when: 1. The detection circuit cannot be calibrated correctly. 2.
PRODUCT WARRANTY 1/1/2002 RKI Instruments, Inc. warranties gas alarm equipment 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 within that period will be repaired or replaced, at our option, free of charge. Parts must be returned to RKI Instruments, Inc. for repair or replacement.
