Rosemount Manual: 371 ORP Sensor | Rosemount Manuals & Guides

Model 371 ORP Sensor

13.5 EuroSenz

™

Instruction Sheet

PN 51A-371ORP/rev.C
January 2011

SPECIFICATIONS

ORP Range: -1500 to 1500 mV

Wetted Materials: Polypropylene, EP,

Glass, and Platinum

Process Connection: Standard PG

13.5 Thread

Electrode Connection: Single Pole

Euro Connector

Temperature Range: 0° - 85°C

(32° - 185°F)

Pressure Range: 100 - 790 kPa abs

(0 - 100 psig)

Specifications subject to change
without notice.

FIGURE 1. Sensor Dimensions

MILLIMETER

INCH

STORAGE

1. It is recommended that electrodes be stored in their
original shipping containers until needed.

2. Do not store at temperatures below -5°C (23°F).

3. Electrodes should be stored with a protective cap
containing KCl solution (PN 9210342).

4. For overnight storage, immerse the sensor in tap
water or 4 pH buffer solution.

ELECTRODE PREPARATION

1. Remove electrode from shipping container.

2. Remove the protective boot covering the electrode
bulb.

NOTE

Do not allow lubricant to coat the platinum band
or reference junction. If it does, wipe it clean
before installation.

INSTALLATION

For sensor orientation, see Figure 2.

For wiring, see Figure 3.

FIGURE 2. Sensor Orientation

For additional information, please visit our website at www.emersonprocess.com/raihome/liquid/.

WARNING

Before removing the sensor, be absolutely certain
that the process pressure is reduced to 0 psig and
the process temperature is lowered to a safe level!

WARNING

The wetted sensor materials may not be compatible
with process com position and operating conditions.
Application compat ibility is entirely the

responsi-

bility of the user.

CAUTION

SENSOR/PROCESS APPLICATION COMPATIBILITY

ATEX DIRECTIVE

Special Conditions for safe use

1. All pH/ORP sensors have a plastic enclosure which must only be cleaned with a damp cloth to avoid the
danger due to a build up of an electrostatic charge.

2. All pH/ORP sensor Models are intended to be in contact with the process fluid and may not meet the 500V
r.m.s. a.c. test to earth. This must be taken into consideration at installation.

FIGURE 3. Electrical Connection

1. INSTRUMENTS MUST BE USED IN MANUAL TEMPERATURE COMPENSATION
MODE.

2. A SEPARATE THERMOCOUPLE MAY BE USED IF TEMPERATURE COMPENSA­TION IS DESIRED. PLEASE CONSULT APPROPRIATE ANALYZER/TRANSMITTER
MANUAL FOR MORE WIRING DETAILS.

FOR USE WITH 1054 SERIES WITH INTEGRAL PREAMP IN ANALYZER,
REQUIRES THE USE OF BNC ADAPTER (PN 9120516) TO BE PLACED ON THE
BLACK WIRE.

3

3

ORP CALIBRATION

1. After making an electrical connection between the
sensor and the instrument, obtain a standard solu­tion of saturated quinhydrone. This can also be
made quite simply by adding a few crystals of quin­hydrone to either pH 4 or pH 7 buffer. Quinhydrone
is only slightly soluble, therefore only a few crystals
will be required.

2. Immerse the sensor in the standard solution. Allow
1-2 minutes for the ORP sensor to stabilize.

3. Adjust the standardize control of the instrument to
the solution value shown in the table below. The
resulting potentials, measured with a clean plat­inum electrode and saturated KCl/AgCl reference
electrode, should be within +/- 20 millivolts of the
value shown in the table below. Solution tempera­ture must be noted to ensure accurate interpreta­tion of results. The ORP value of saturated quinhy­drone solution is not stable over long periods of
time. Therefore, these standards should be made
up fresh each time they are used.

4. Remove the sensor from the buffer, rinse, and
install in the process.

MAINTENANCE

Electrodes should respond rapidly. Sluggishness, off­sets, and erratic readings are indicators that the elec­trodes may need cleaning or replacement.

1. To remove oil deposit, clean the electrode with a
mild non-abrasive detergent.

2. To remove scale deposits, soak electrodes for 30 to
60 minutes in a 5% hydrochloric acid solution.

3. ORP (metallic) electrodes should be polished with
moistened baking soda.

pH 4 Solution pH 7 Solution

Temp °C 20 25 30 20 25 30

mV Potential 268 264 260 94 87 80

ORP of Saturated Quinhydrone Solution (millivolts)

NOTE: NEWER CABLES MAY HAVE
DIFFERENT WIRE COLORS. IN THIS
CASE, THE BLACK WIRE IS REFER­ENCE, AND THE CLEAR/COPPER
WIRE IS mV IN.

Emerson Process Management

2400 Barranca Parkway
Irvine, CA 92606 USA
Tel: [phone]
Fax: [phone]

http://www.raihome.com

© Rosemount Analytical Inc. 2011