Operation With A Fixed T.c; Modei 1181 Ph Start-Up - Emerson Rosemount 1181pH TRANSMITTER Instruction Manual

MODEL 1181pH/ORP
3.3.3 If it is not practical to take a grab sample, rea-
sonable accuracy can be obtained by the buffer solu-
tion method (refer to paragraph 3.3.1). Exceptions to
this are streams or processes with chemical composi-
tions very different from buffer solutions such as high
purity water, miscible solvents and other dilute solu-
tions. The grab sample methods should be used for
solutions of this type.
3.4 OPERATION WITH A FIXED T.C. In the event it is
desired to operate the Model 1181 pH with a fixed T.C.,
refer to Table 3-4 for the proper resistance value.
TABLE 3-4.
Resistance Value for Fixed T.C.
Temperature Ohms (3K RTC) Ohms (Pt-100)
0°C
10°C
20°C
25°C
30°C
40°C
50°C
60°C
70°C
80°C
90°C
100°C
To compute the resistance values for temperature
other than those listed, use the following equations:
RTC = 2663 + (13.5 x °C)
RDC = 100 + (.385 x °C)
When using a fixed T.C. with the Rose-
mount Analytical Model 381 sensor, con-
sult the 381 Instruction Manual.
After the appropriate resistor has been selected, dis-
connect the T.C. black and white leads going to pre-
amp and connect the resistor in their place (see Figure
2-4).
3.5 MODEL 1181ORP START-UP. This paragraph
describes the range selection, electronic calibration,
and system calibration of Model 1181 ORP Two-Wire
Transmitter. The Model 1181 ORP is factory calibrated
for an ORP range of ±1000 mV. If a different range is
desired, refer to paragraph 3.5.1. If the ±1000 mV
range is suitable, proceed to paragraph 3.5.2.
22
2663 100.00
2798 103.85
2833 107.70
3000 109.62
3067 111.55
3202 115.40
3337 119.25
3472 123.10
3607 126.95
3742 130.80
3877 134.65
4012 138.50
NOTE
3.5.1 Range Selection. A matrix showing the switch
position of S1 for the various ranges is in Figure 3-1.
This switch is located on the circuit side of the enclo-
sure. See Figure 3-3 for ORP range switch selection
procedure. The following is an example of the switch
position required for ±200 mV range.
1. The mid-scale mV range is 0 mV. Switches 6 and
7 must be closed and switches 5 and 8 must be
opened.
2. A span of 400 mV is required. Switch 2 must be
closed and switches 1, 3, and 4 must be opened.
3. Any mid-scale mV range between –1200 and
+1200 may be selected.
4.Spans between 200 to 2400 mV are available.
3.5.2 Polarity Selection. The Model 1181 ORP is
calibrated in the American convention of millivolt
measurement, with 0 millivolt (mV) being mid-scale
(12 mADC). All positive potentials are downscale
and all negative potentials are upscale. The meas-
urement may be reversed to accommodate the
European convention (see Figure 6-2).
1.Remove jumper from 2 and 3.
2.Install jumper 1 and 4.
3.The Model 1181 ORP has now been modified to
accommodate the European convention. Negative
potentials downscale and positive upscale.
Negative potentials are reducing indica-
tions and positive potentials are oxidizing
indications.
3.5.3 Electronic Calibration Using the Preamplifier.
The Model 1181 ORP may be calibrated using the pre-
amplifier within the ORP sensor.
1. Retain all connections from the ORP sensor to the
Model 1181 ORP.
2. Using a Model 213 pH/ORP Simulator or equiv-
alent, remove the ORP electrode connector from
the preamplifier and install the connector from the
Model 213 to the preamplifier.
3. Install an ammeter capable of indicating 4 to 20
mADC between TB1-2 and TB1-3 in the Model
1181 ORP. Disconnect the indicating meter during
this test. If a LCD is used refer to paragraph 3.13 for
calibration.
4. Place the Range Switch on the Model 213 for a
+1000 mV output. Adjust ZERO control (under
serial label) for a 4 mADC output.
SECTION 3.0
START UP, AND CALIBRATION
NOTE