35-3010A-12 Sample-Draw Detector • 9
Flow Blocks
The flow block is in the lower right corner of the sample-draw detector. The oxygen, CO, and H
2
S
sensors are installed in the flow block. The flow block routes the sampled air to each sensor.
EXHAUST Fitting
The EXHAUST fitting on the bottom of the housing allows the gas sample to exit the sample-draw
detector. The EXHAUST fitting accepts 1/4 in. rigid tubing. See “Installation” on page 12 to
connect tubing to the EXHAUST fitting.
Detection System
The detection system consists of the gas sensors, oxygen transmitter, preamp circuit board, and the
main circuit board.
Oxygen Sensor
The oxygen sensor is installed in the lower right of the larger flow block. It consists of a cylindrical
body which houses the detection elements and a cable which terminates in a round 7-pin male
connector. The sensor connector mates to a 7-position socket that is wired to the main PCB.
Carbon Monoxide Sensor
The carbon monoxide gas sensor is installed in the upper left side of the larger flow block. It has 4
pins which mate with sockets in the preamp circuit board.
Hydrogen Sulfide Gas Sensor
The hydrogen sulfide gas sensor is installed in the upper right side of the larger flow block. It has
4 pins which mate with sockets in the preamp circuit board.
Oxygen Transmitter
The oxygen transmitter is mounted above the main circuit board. The amplifier includes the
amplifier type selector, two internally wired terminal strips, span pot, zero pot, and test points.
Figure 3: Oxygen Transmitter
Transmitter Type Selector
The transmitter type selector is near the bottom left corner of the amplifier. It is to the left of the
detector terminal strip and below the span pot.
The transmitter included with the sample-draw detector is designed for use with RKI’s oxygen
and toxic gas sensors. The transmitter type selector determines for which sensor the amplifier is
+
BATT
24V
TP
+
TP
-
4/20
FB
+
RD
T OXIC
OXY
G
Sensor
Terminal Strip
BK
W
OXY
SPAN
T OXIC
Test Point TP-
Transmitter Type Selector,
Set To OXY
Span Pot
Test Point TP+
ZERO
Zero Pot
Interconnect
Terminal Strip