RKI Instruments Inert Gas Testing Eagle with Two Pumps - Manual (Page 14)

8 • Description Eagle Instruction Manual
approximately two years.
Combustible Gas Sensor
The combustible gas (LEL) sensor is mounted with the flame arrestor
down in the sensor block to allow the sample flow to diffuse into the
sensor. Five pins extend from the top of the sensor. The sensor cable
connects to the pins on one end and terminates in a four-position
connector, which plugs into the COMB socket on the analog print
circuit board (PCB).
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 Eagle into a reading of combustible gas
concentration.
Since the Eagle is intended for use in an inert atmosphere but the
catalytic type LEL sensor requires some oxygen for the sensor to
operate, the Eagle uses a special flow system and a second pump to
provide dilution by introducing air to the sample before delivery to
the LEL sensor.
Oxygen Sensor
The oxygen (O
2
) sensor is mounted face down in the sensor block to
allow the sample flow to diffuse into the sensor. A multi-pin plug
connects the O
2
sensor to the CN2 socket on the analog PCB.
The O
2
sensor is an electrochemical cell, which reacts to the oxygen in
the atmosphere and produces a voltage proportional to the oxygen
concentration. This voltage is converted by the Eagle into a reading of
oxygen concentration.
H
2
S Sensor
The H
2
S sensor has a cylindrical body and is mounted face down in
the sensor block. A three-position connector from the sensor plugs
into EC1 socket on the analog PCB.
The H
2
S sensor is an electrochemical cell, which reacts to the target
gas in the atmosphere, producing a current proportional to the
concentration of gas. The current is converted by the Eagle into a
reading of target gas concentration.
H
2
Compensated CO Sensor
The H
2
compensated CO sensor is mounted in the front half of the
instrument case. This sensor includes a dedicated amplifier with