RKI Instruments 35-3000RKA-10 - Manual (Page 8)

8 • 35-3000RK-10 PPM Hexane Sample Draw Detector
Amplifier
The amplifier is mounted to the left of the detector. It is installed on a small plate with
adhesive foam and the plate is mounted to two standoffs. The amplifier converts the non-
linear electrical output from the detector to a linear 4 to 20 mA signal that corresponds to
the detection range and transmits the signal to a gas monitoring controller. The amplifier
consists of the span pot, zero pot, load voltage pot, gas select jumper strip, controller
terminal strip, detector terminal strip and test points.
Zero Pot
The zero pot is located in the upper right corner of the amplifier (see Figure 1). Use a small
flat blade screwdriver to turn the zero pot’s adjustment screw and adjust the amplifier’s
zero (fresh air) output during the start-up and calibration procedures.
Span Pot
The span pot is located below the zero pot (see Figure 1). Use a small flat blade
screwdriver to turn the span pot’s adjustment screw and adjust the amplifier’s gas
response output during the calibration procedure.
Load voltage pot
The load voltage pot is located to the left of the zero and span pots (see Figure 1). The load
voltage pot is not needed for normal scheduled maintenance, so it is a right angle pot that
is not accessible unless the amplifier is lifted out of the sample draw detector enough to
access the adjustment screw. Use a small flat blade screwdriver to turn the load voltage
pot’s adjustment screw and adjust the amplifier’s detector load voltage when the detector
or amplifier is replaced.
CAUTION: The amplifier includes additional pots. They are factory-set. Do not adjust them.
Gas Select Jumper Strip
The gas select jumper strip is a three position pin style terminal strip located in the upper
left corner of the amplifier. A label next to the jumper strip indicates which pins must be
shorted to select hexane or hydrogen. A jumper block is installed at the factory over pins 1
& 2 to select hexane as the gas type. The gas type defines the linearizing curve used by the
amplifier to linearize the detector output.
Controller and Detector Terminal Strips
The controller terminal strip and detector terminal strip are three position terminal strips.
The controller terminal strip is located on the right side of the amplifier and the detector
terminal strip is to the right of it. Both terminal strips are factory wired to the sensor and
main circuit board.
Test points
The test points are located on the left side of the amplifier. The black - test point is in the
upper left corner and the red + test point is located below it on the other side of the gas
select jumper strip. A 100 mV - 500 mV output is available at these test points for use
during calibration.