RKI Instruments EAGLE 2 Manual - Manual (Page 18)

8 • Instrument Description EAGLE 2 Operator’s Manual
Case
The EAGLE 2’s sturdy, high-impact plastic case is radio frequency (RF)
resistant and is suitable for use in many environmental conditions, indoors
and out. The case is dust proof and water resistant. It’s two main components,
the top case and bottom case, are held together with three screws located on
the bottom case. The interface between the top case and bottom case is
gasketed. A sturdy, well balanced handle on the top case allows you to hold
the instrument comfortably. A clear plastic window is located on the top case
to the front of the handle for viewing the LCD.
A removable battery case is located at the rear of the bottom case. A
thumbscrew secures the battery case to the bottom case. The interface
between the battery case and the bottom case is gasketed. Six raised feet on
the bottom of the case, four on the bottom case and two on the battery
compartment, raise the EAGLE 2 slightly from the surface on which it rests.
Sensors
The EAGLE 2 uses up to six sensors to monitor combustible gas, oxygen
(O
2
), carbon monoxide (CO), hydrogen sulfide (H
2
S), and various other toxic
gases simultaneously. The sensors are located inside the EAGLE 2 bottom
case and are installed in the flow chamber. The sensors described below are
the four standard sensors. See “Appendix D: PID Sensors” for a description
of the PID sensors, “Appendix E: ESM-01 Toxic Sensors” for a description
of the ESM-01 toxic sensors, “Appendix F: TC Sensors” for a description of
the TC sensors, “Appendix G: Infrared Carbon Dioxide Sensors” for a
description of the IR CO
2
sensors, “Appendix H: Infrared Methane Sensor”
for a description of the IR methane sensors, and “Appendix I: Infrared
Hydrocarbon Sensor” for a description of the IR hydrocarbon sensor. The
standard sensors use different detection principles as described below.
Catalytic Combustible Gas Sensor (LEL Sensor)
The catalytic combustible gas (LEL) sensor detects combustible gas in the
%LEL range. It uses a catalytic element for detection. The reaction of gas
with oxygen on the catalyst causes a change in the resistance of the element
which changes the current flowing through it. The current is amplified by the
EAGLE 2’s circuitry, converted to a measurement of combustible gas
concentration, and displayed on the LCD.
The LEL sensor housing includes a sintered metal flame arrestor on one end
that allows gas to diffuse into the sensor. On the other end, five pins extend
from the sensor. The sensor cable connects to these pins on one end and
terminates in a four-position connector on the other end which plugs into the
HC socket on the main PCB (see “Main PCB” on page 12).