Operating With Integral Preamp (Accessory) - Emerson Rosemount 1181pH TRANSMITTER Instruction Manual

MODEL 1181pH/ORP
3.6.2 Ferric-Ferrous Ammonium Sulfate Test.
Although this standard ORP solution is not as easy to
prepare as the quinhydrone solution in Section 3.6.1, it
offers a much more stable solution which will maintain
its millivolt value for approximately one year when
stored in glass containers.
Dissolve 39.2 grams of reagent grade ferrous ammo-
nium sulfate [Fe (NH 4 ) 2 (SO 4 ) 2 • 6H 2 0] and 48.2
grams of reagent grade ferric ammonium sulfate
[F2NH 4 (SO 4 ) 2 12H 2 0] in approximately 700 milliliters
of water (distilled water is preferred, but tap water is
acceptable). Slowly and carefully add 56.2 milliliters of
concentrated sulfuric acid. Add sufficient water to bring
the total solution volume up to 1,000 milliliters. This
solution (ferric-ferrous ammonium sulfate) will produce
a nominal ORP of 476 ±20 mV at 25°C when used with
a saturated KCl/AgCI reference electrode (or 430 mV
with a Calomel reference electrode) and platinum
measuring electrode. The above potentials may be
measured from the electrode lead wires that connect to
TB 2-1 and TB 2-2 of the Model 1181 ORP Transmitter
(see Figure 2-2).Some tolerance in mV values is to be
expected due to the rather large liquid reference junc-
tion potentials which can arise when measuring this
strongly acidic and concentrated solution. However, if
the measuring electrodes are kept clean and in good
operating condition, consistent repeatable calibrations
can be achieved.
3.7 OPERATING WITH
(ACCESSORY). The preamp may be ordered as an
accessory to the Model 1181 pH/ORP. This enables
the user to mount the preamp integral to the Model
1181 pH/ORP. This will eliminate the use of a junction
box when remote preamps are required.
This preamp is applicable to explosion-proof (Class 1,
Group C and D, Div. 1) installations and to applications
where the preamp must be remote from the sensor due
to high temperatures (above 80°C).
Two types of preamps are available. P/N 22744-01 is
compatible with a 3K RTD. P/N 22743-01 is compati-
ble with a 100 ohm RTD.
Please refer to Figure 2-3 for installation instructions.
The user must remove the BNC electrode connector
from the coax cable supplied with the sensor and pre-
pare the coax as shown in Figure 2-4.
Due to space limitations the meter mounting position is
restricted (see insert, Figure 2-3). Additionally, the inte-
gral preamp accessory must be used with the analog
meter (Code 01 or Code 03) option, or with the LCD
indication (Code 06) option. In order to use the integral
preamp accessory with blind transmitters (Code 02),
P/N 3002468 (tall cover) must be ordered as a spare
part. The integral preamp accessory is not available
with LCD indication (Code 04) option.
The maximum distance between the Model
1181 pH/ORP with an integral preamp and
the sensor is 15 feet (4.5m).
The Model 1181 pH/ORP with integral preamp should
not be used with a ruggedized pH electrode at operat-
ing temperatures of less than 25°C (77°F).
SECTION 3.0
START UP, AND CALIBRATION
INTEGRAL PREAMP
NOTE
25