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The Model 851 Transmitter can be calibrated
out-of-system.
Figure 4-2 shows an out-of -system piping
diagram.
CALIBRATION INSTRUMENTATION
NOTE – Calibration equipment should be
accurate to five times the accuracy of the
transmitter.
The Model 851 Transmitter can be calibrated
using an ammeter or voltmeter Figure 4-3.
Use an ammeter with internal shunt impedance
greater than 10 ohms will give erroneous
readings.
Use a voltmeter with a 10 ohm precision resistor
connected as shown in Figure 4-3.
1. Apply 0 psi pressure to input.
2. Adjust "Zero" pot to obtain 4mA (40 mV)
output.
3. Apply pressure which corresponds to "full
scale" pressure to input.
4. Adjust "span" pot to obtain 20 mA (200
mV) output
5. Repeat steps 1 through 4 until output
values are achieved.
6. If "span" required differs from previous
span by more than 10%, adjust
"turndown" pot prior to "span" pot and
proceed to step 4.
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