RKI Instruments 35-3001-09 - Manual (Page 10)

6 • 35-3001-09 Oxygen/Hydrogen Sulfide Sample-Draw Detector
Hydrogen Sulfide Sensor/H
2
S Amplifier
The hydrogen sulfide sensor is a plug-in sensor that plugs into the back of the H
2
S amplifier. The
sensor and amplifier are retained in the flow block by two screws. The flow block is mounted to the
middle of the main circuit board. It is the upper of the two flow blocks mounted to the main circuit
board.
Through a series of chemical and electronic reactions, the H
2
S sensor produces a millivolt output
that is proportional to the detection range of the sample-draw detector. A red wire and a blue wire
extend from the H
2
S amplifier and allow connection to the detector/amp terminal strip.
Figure 3: H
2
S Amplifier Component Location
Zero Pot
The zero pot is located in the lower right corner of the amplifier (see Figure 3). Use a small flat
blade screwdriver to turn the zero pot’s adjustment screw and adjust the amplifier’s zero output
during the start up and calibration procedures. Turn the adjustment screw clockwise to increase the
zero output and counterclockwise to decrease the zero output.
Span Pot
The span pot is located to the left of the zero pot (see Figure 3). Use a small flat blade screwdriver
to turn the span pot’s adjustment screw and adjust the amplifier’s gas response during the
calibration procedure. Turn the adjustment screw clockwise to increase the span output and
counterclockwise to decrease the span output.
Test Points
The test points are on the top edge of the amplifier (see Figure 3). The test points produce a 100 mV
to 500 mV output that corresponds to the sample-draw detector’s 4 to 20 mA output. Use the test
points and a voltmeter to measure the amplifier’s output during the start-up and calibration
procedures. The black test point (CAL 2) in the upper left corner is the negative (-) test point and
the red test point (CAL 1) in the upper right corner is the positive (+) test point.
Zero Pot
Span Pot
Test Points
100-500 mV Range