RKI Instruments 35-3000RKA-H2S - Manual (Page 4)

4 • Sample-Draw Hydrogen Sulfide Gas Detection
Status lights
Two status lights are above the flowmeter. They are also visible through the window in
the housing door.
Pilot light
The green Pilot light is on when the sample-draw detector is receiving power from the
Pioneer.
Fail light
The red Fail light is on when the sample flow rate is below the low flow level.
NOTE: The default low flow level is 0.6 SCFH (±0.2). See “Adjusting the Low Flow
Setting” on page 13 to adjust this setting.
Pressure switch
The pressure switch is mounted to the opposite side of the main circuit board. The
pressure switch monitors the flow rate of the incoming gas sample.
If the flow rate falls below the preset low flow level, the pressure switch causes the fail
relay to interrupt the signal in the 4-20 mA line. This causes a downscale reading at the
monitor. The low flow level is factory-set at 0.6 SCFH (±0.2 SCFH).
EXHAUST fitting
The EXHAUST fitting on the right side of the housing allows the gas sample to exit the
sample-draw detector. The EXHAUST fitting accepts 1/4 in. rigid tubing. See the
Installation section on page 6 to connect tubing to the EXHAUST fitting.
Detection System
The detection system consists of the hydrogen sulfide gas sensor, the hydrogen sulfide
transmitter, and the main circuit board.
Hydrogen sulfide gas sensor
The hydrogen sulfide gas sensor is installed in a cavity block. The cavity block is mounted
to the aluminum
subpanel on the right of the sample-draw detector. The hydrogen
sulfide gas sensor includes the sensor and the cable with connector.
NOTE: The cavity block includes a cavity for a second hydrogen sulfide or a carbon
monoxide sensor. This version of the sample-draw detector does not include the
second sensor.
Sensor
The sensor is pushed into the cavity block and held in place by two o-rings. Through a
series of chemical and electrical reactions, the sensor produces an electrical output that is
proportional to the detector range of the transmitter.
Cable w/Connector
The sensor has a two wire cable with a 4-pin connector soldered to it. The connector is
plugged into the sensor connector in the lower right of the Main Circuit Board.