RKI Instruments 35-3000RKA-10 - Manual (Page 7)

35-3000RK-10 PPM Hexane Sample Draw Detector • 7
Bypass valve
The bypass valve is to the left of the flowmeter. The bypass valve adjusts the flow rate to
the detector. Use a flat-blade screwdriver to adjust the bypass valve.
NOTE: The bypass valve allows fine adjustments of the flow rate to the detector. To
adjust the total flow and for a wider range of adjustment, use the flow adjust pot
(see Figure 1).
Flow Block
The flow block is an aluminum block with a chamber for the detector and passages that
route the sample to and from the detector. It is located in the lower right corner of the
sample draw detector. The flow block has an unused chamber that is used for an oxygen
detector in other versions of the 35-3000RK.
Status LEDs
Two status LEDs are above the flowmeter. They are also visible through the window in the
housing door.
Pilot LED
The green Pilot LED is on when the sample-draw detector is receiving power from the
Pioneer.
Fail LED
The red Fail LED is on when the sample flow rate is below the low flow level.
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 SC FH). See “Adjusting the
Low Flow Setting” on page 20 to adjust this setting if necessary.
Detection System
The detection system consists of the ppm hexane detector, the amplifier, and the main
circuit board.
PPM Hexane Detector
The ppm hexane detector is a MOS type (metal oxide semiconductor) detector packaged
in a 5 pin plug-in detector housing with a sintered metal flame arrestor on one end
allowing ambient air to diffuse into the detector. The flame arrestor also contains any
sparks which may occur within the detector. The 5 pins allow you to connect the detector
to the detector cable which has a mating 5 pin connector. The three color-coded leads of
the detector cable allow you to connect the detector to the amplifier. The output of the
detector is non-linear and is linearized by the amplifier (see below).
The detector is installed in an aluminum flow block. The flow block is mounted to the
aluminum
subpanel near the bottom right corner of the sample draw detector.
NOTE: The flow block includes a chamber for an oxygen sensor. This version of the
sample draw detector does not include the oxygen sensor.