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MODEL 5700
IV. CALIBRATION AND ADJUSTMENT
After each adjustment in the following steps, allow time for the changes to stabilize. Recheck all
adjustments. Turn instrument on and allow at least 5 minutes warm-up before calibration and
adjustments are made.
A. ZERO ADJUSTMENT
1. Remove sample inlet tube from sample metering valve outlet fitting and introduce
a sample of zero air or nitrogen, free of “CO” and interfering gases, to the sample
inlet tube. The sample flow should be between 0.5 and 1.5 SCFH.
2. Verify that the green NORMAL light is on, the red ALARM light is flickering
about once a second and the display is showing “00". If the display is showing
other than “00", adjust the ZERO potentiometer (next to the display) so that the
reading is “00". Clockwise adjustment increases reading. Notice that the display
jumps from 00 to +02 to -02. Try to set the potentiometer midway between the
two extremes. Remove the zero air sample.
B. SPAN ADJUSTMENT
To set the span of the instrument, follow the steps below:
1. Introduce a known sample of 50 to 150 PPM “CO” to sample inlet tube. The
sample flow should be between 0.5 to 1.5 SCFH.
2. Verify that the green NORMAL light is off, the red ALARM light is on full bright
and the stabilized reading (after approximately one minute) is equal to the known
concentration of “CO”. If the display is showing a difference, adjust the SPAN
potentiometer (next to the display) to obtain proper value. Turn clockwise to
increase reading. If the span adjustment cannot be made as indicated, the detector
needs to be replaced. SEE MAINTENANCE, V.B.
3. Remove the known sample and return the sample inlet tube to the sample metering
valve outlet fitting and lock in place..
The instrument is now properly adjusted for use.
C. ALARM ADJUSTMENT
The alarm level (initially set as shown on the specification page) can be changed if
desired, as follows:
1. Remove the screw on upper front edge of right side of case.
2. Using a small-blade screwdriver through the screw hole, locate the ALARM
adjustment slotted potentiometer.
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