Rosemount Analytical 381 Operating Manual
pH/ORP Sensor
Instruction Manual
PN 51-381+/rev.G
March 2012
Model 381+
CAUTION
SENSOR/PROCESS
APPLICATION COMPATIBILITY
The wetted sensor materials may not be
compatible with process com position
and operating conditions. Application
compat ibility is entirely the responsibility of the user.
DANGER
HAZARDOUS AREA INSTALLATION
Installations near flammable liquids or in hazardous
area locations must be carefully evaluated by qualified on site safety personnel. This sensor is not
Intrinsically Safe or Explosion Proof.
To secure and maintain an intrinsically safe installation, the certified safety barrier, transmitter, and
sensor combi nation must be used. The installation system must comply with the governing
approval agency (FM, CSA or BASEEFA/CENELEC) hazardous area classification requirements. Consult your analyzer/transmitter instruc tion manual for details.
Proper installation, operation and servicing of this
sensor in a Hazardous Area Instal lation is entirely
the responsibility of the user.
ESSENTIAL INSTRUCTIONS
READ THIS PAGE BEFORE PROCEEDING!
Rosemount Analytical designs, manufactures, and tests its products to meet
many national and international standards. Because these instruments are
sophisticated technical products, you must properly install, use, and maintain them to ensure they continue to operate within their normal specifications. The following instructions must be adhered to and integrated into your
safety program when installing, using, and maintaining Rosemount
Analytical products. Failure to follow the proper instructions may cause any
one of the following situations to occur: Loss of life; personal injury; property damage; damage to this instrument; and warranty invalidation.
• Read all instructions prior to installing, operating, and servicing the product. If this Instruction Manual is not the correct manual, telephone 1-800654-7768 and the requested manual will be provided. Save this
Instruction Manual for future reference.
• If you do not understand any of the instructions, contact your Rosemount
representative for clarification.
• Follow all warnings, cautions, and instructions marked on and supplied
with the product.
• Inform and educate your personnel in the proper installation, operation,
and maintenance of the product.
• Install your equipment as specified in the Installation Instructions of the
appropriate Instruction Manual and per applicable local and national
codes. Connect all products to the proper electrical and pressure sources.
• To ensure proper performance, use qualified personnel to install, operate,
update, program, and maintain the product.
• When replacement parts are required, ensure that qualified people use
replacement parts specified by Rosemount. Unauthorized parts and procedures can affect the product’s performance and place the safe operation of your process at risk. Look alike substitutions may result in fire, electrical hazards, or improper operation.
• Ensure that all equipment doors are closed and protective covers are in
place, except when maintenance is being performed by qualified persons,
to prevent electrical shock and personal injury.
Emerson Process Management
2400 Barranca Parkway
Irvine, CA 92606 USA
Tel: (949) 757-8500
Fax: (949) 474-7250
http://www.rosemountanalytical.com
© Rosemount Analytical Inc. 2012
About This Document
This manual contains instructions for installation and operation of the Model 381+ High pH/ORP Sensor. The following
list provides notes concerning all revisions of this document.
Rev. Level Date Notes
0 5/01 This is the initial release of the product manual. The manual has been refor-
matted to reflect the Emerson documentation style and updated to reflect any
changes in the product offering.
A 6/02 Updated multiple drawings throughout.
B 7/02 Added 1055 wiring drawing and updated kPa references.
C 9/02 Revised drawing captions on page 9.
D 9/04 Add Xmt wiring drawings and delete Ultrasonic cleaner.
E 11/07 Added M certs on back page.
G 3/12 Update addresses - mail and web
MODEL 381+ pH/ORP TABLE OF CONTENTS
MODEL 381+ pH/ORP SENSOR
TABLE OF CONTENTS
Section Title Page
1.0 DESCRIPTION AND SPECIFICATIONS........................................................... 1
1.1 Features and Applications................................................................................. 1
1.2 Specifications .................................................................................................... 2
1.3 Ordering Information ......................................................................................... 3
2.0 INSTALLATION ................................................................................................. 4
2.1 Installation ......................................................................................................... 4
2.2 Submersion Installation .................................................................................... 4
2.3 Insertion Installation ......................................................................................... 4
2.4 Flow Through Installation ................................................................................. 7
2.5 Flow Powered Cleaner Installation ................................................................... 7
2.6 Wiring ................................................................................................................ 7
3.0 START-UP......................................................................................................... 14
3.1 Start-Up............................................................................................................. 14
3.2 pH Calibration ................................................................................................... 14
3.3 ORP Standardization......................................................................................... 14
4.0 MAINTENANCE ................................................................................................ 16
4.1 General ............................................................................................................. 16
4.2 Sensor Removal................................................................................................ 16
4.3 Monthly Maintenance ........................................................................................ 16
4.4 Annual Maintenance ......................................................................................... 16
4.5 Electrode Checking and Standardization .......................................................... 17
5.0 TROUBLESHOOTING ...................................................................................... 18
5.1 Sensor Troubleshooting .................................................................................... 18
5.2 T.C. Element Evaluation.................................................................................... 19
5.3 Ultrasonic Cleaner/Generator Troubleshooting................................................. 19
6.0 RETURN OF MATERIAL................................................................................... 20
i
MODEL 381+ pH/ORP TABLE OF CONTENTS
MODEL 381+ pH/ORP SENSOR
LIST OF FIGURES
Figure No. Title Page
2-1 Sensor Component Locator Diagram................................................................ 5
2-2 Submersion Installation Diagram ...................................................................... 6
2-3 Insertion Installation Diagram............................................................................ 6
2-4 Flow Through Installation Diagram.................................................................... 7
2-5 Installation Details Low Flow Conditions (Code -03 and -04)............................ 8
2-6 Flow Powered Cleaner Component Locator (Code -04)................................... 8
2-7 Wiring Model 381+ to Models 54, 3081, and 81................................................ 9
2-8 Wiring through J-Box with Extension Board to Models 54, 3081, and 81 ......... 9
2-9 Wiring Model 381+-52 through J-Box with Preamp to Models 54, 3081, & 81 . 10
2-10 Wiring to Solu Cube Junction Box (PN 23054-03) ............................................ 11
2-11 Wiring Model 381+-31-41/43-55 to Model 1055-10-22-32 ................................ 11
2-12 Wiring Model 381+-31-42-55 to Model 1055-22-32 .......................................... 12
2-13 Wiring Model 381+-52-62 to Model 1055-22-32 through Remote J-Box .......... 12
2-14 Wiring Model 381+-41-52 to Model Xmt-P........................................................ 13
2-15 Wiring Model 381+-55 to Model Xmt-P ............................................................. 13
LIST OF TABLES
Table No. Title Page
1-1 Recommended Accessories and Spare Parts................................................... 2
3-1 ORP of Saturated Quinhydrone Solutions ........................................................ 14
5-1 Troubleshooting................................................................................................. 18
5-2 T.C. Element Resistance................................................................................... 19
ii
at temperatures greater than 80°C, the preamplifier
must be located in a remote junction box or in the
instrument.
A double junction, gel-filled reference cell, a standard
feature of the Model 381+, improves sensor life when
unknown reference cell contaminants, such as sulfides, may exist. The gel solution maintains its viscosity at high temperatures, and resists the effect of pumping and dilution, resulting in an extended service life. A
choice of wood or ceramic liquid junction allows the
user to optimize performance by emphasizing reference lifetime (wood) or chemical resistance (ceramic).
In flow applications where crystalline or viscous coatings, such as calcium carbonate or petroleum oils, may
coat the electrode surfaces and impede the sensor’s
performance, the flow-powered cleaning option may be
used. A specially designed flow chamber directs the
process fluid in a circular path carrying four Teflon
1
balls which clean the electrode surface, physically
preventing accumulation of coating materials. Flowpowered cleaning is suitable for all hazardous area
applications.
The Model 381+ comes with Pt100 temperature compensation and is compatible with the Models 54e
pH/ORP and 1055 Analyzers, and 81, 3081, 4081,
5081-P, and Xmt-P pH/ORP Transmitters.
* Patent pending
1
Teflon is a registered trademark of E.I. du Pont de Nemours & Co.
1
Model 381+ pH/ORP SECTION 1.0
DESCRIPTION AND SPECIFICATIONS
SECTION 1.0
DESCRIPTION AND SPECIFICATIONS
• ADVANCED ON-LINE SENSOR DIAGNOSTICS* of the Model 381+ when used with the
Models 54e pH/ORP and 1055 Analyzers, or 81, 3081, 4081, 5081-P, and Xmt-P pH/ORP
Transmitters.
• MOLDED POLYETHERSULFONE (PES) BODY provides compatibility with a variety of processes.
• MODULAR DESIGN facilitates maintenance by eliminating mounting brackets and extrane-
ous hardware.
• INTEGRAL PREAMPLIFIER provides reliable signal transmission.
• DOUBLE JUNCTION, GEL-FILLED, REFERENCE CELL provides high temperature performance,
extended service life, and resists the effects of pumping, dilution and contamination.
1.1 FEATURES AND APPLICATIONS
The Rosemount Analytical Model 381+ Sensor measures the pH or the Oxidation Reduction Potential (ORP)
of aqueous solutions in pipelines, open tanks or ponds.
The sensor is used in most indus trial applications including water and waste treatment plants.
The Model 381+pH Sensor features continuous on-line
advanced diagnostics that allow the user to identify sensor failures such as coated reference junction or broken
glass. Sensor diagnostics result in time and money savings by reducing the guesswork in sensor maintenance
and replacement requirements. On-line sensor diagnostics are made possible by calculation of the temperature
corrected glass electrode impedance and by characterizing failure modes.
The sensor is housed in a molded PES body and has two
O-ring seals with breach lock threads which secure the
PES cover. This provides a waterproof union for long
operating life and easy removal for routine maintenance.
The modular body design eliminates the need for internal mounting brackets, terminal brackets and screws.
All components are screw-type or plug-in-place, allowing for fast simple service.
The integral preamplifier conditions the high impedance glass elec trode signal at the sensor, providing a
transmission capability of up to 1000 feet (304.8
meters). The Rosemount Analytical method of
preampli fication has become the industry standard for
reliable pH measurement. In submersion applications
2
Model 381+ pH/ORP SECTION 1.0
DESCRIPTION AND SPECIFICATIONS
1.2 SPECIFICATIONS
Materials of Construction:
Body, Cover and Flow Cell: Polyethersulfone (PES)
O-Rings: Viton1.
Measuring Electrode: Glass (platinum for ORP)
Liquid Junction: PVDF/wood (Code 20) or
PVDF/ceramic (Code 21)
Solution Ground/Temperature Compensator: 316
Stainless steel/EPDM
Process Connections: Submersion: 3/4-inch MNPT
Insertion: 2 “ MNPT, Flow Through: 3/4 ” MNPT
Measuring Range: pH: 0-14
ORP: –1400 to +1400 mV
Temperature Compensation: Automatic, 0 to 100°C
(32 to 212°F)
Maximum Pressure/Temperature Rating:
790 kPa abs at 100°C (100 psig at 212°F)
Cable: Prepped (P/N 23646-01)/unprepped
(P/N 9200273)
Weight/Shipping Weight: 1.0 kg/1.7 kg (2.2 lbs/3.7lbs)
1
Viton is a registered trademark of E.I. duPont de Nemours & Co.
TABLE 1-1 Recommended Accessories and Spare Parts
P/N DESCRIPTION QUANTITY
2000734 Liquid Junction, Kynar/Wood 2
2000735 Liquid Junction, Kynar/Ceramic 2
22694-00 Electrode, pH, GP 2
22694-01 Electrode, High pH 2
22694-02 Electrode, pH, Ruggedized 2
22694-03 Electrode, pH, HF Resistant 4
22697-00 Electrode, pH Combination
22697-01 Electrode, High pH, Combination 4
22723-00 Flow Powered Cleaner Balls (Qty 9) 1
22731-00 ORP Electrode, Platinum 2
22751-00 O-Ring Kit (Qty 5), Upper Body 1
22751-01 O-Ring Kit (Qty 5), Lower Body 1
22811-01 Flow Powered Cleaner Retrofit Kit for Code -00,-02
22892-00 Flow Powered Cleaner Retrofit Kit for Code -03
23018-00 Reference Electrode, Microjunction 2
23561-00 Preamplifier, Integral to 381+ 1
23550-00 Junction Box, remote, with Extension Board, 54, 54e, 1055, 81, 3081, 4081, 5081, Xmt Compatible
23551-00 Sensor Body complete, Pt 100 TC, 1
23552-00 Sensor Cover with 15 ft. Cable 1
23552-01 Sensor Cover with 15 ft. Coax Cable, without BNC 1
23552-02 Sensor Cover with 50 ft. Cable 1
23646-01 Cable extension, 11 conductor, Shielded, Prepped, Price/Foot
23555-00 Junction Box, with Models 54, 54e, 1055, 81, 3081, 4081, 5081, Xmt Preamplifier
23557-00 Preamplifier for Remote Junction Box, 54, 54e, 1055, 81, 3081, 4081, 5081, Xmt Compatible 1
32602-00 Flow Cell, PES 1
32605-00 Electrode Shroud, PES
32606-00 Flow Cell Coupling Nut, PES
32793-00 Flow Powered Cleaner, Ring
32794-00 Flow Powered Cleaner Chamber
9200273 Cable extension, 11 conductor, Shielded, Unprepped Price/Foot
9210012 Buffer Solution, 4.01pH, 16 oz 4
9210013 Buffer Solution, 6.86pH, 16 oz 4
9210014 Buffer Solution, 9.18pH, 16 oz 4
R508-160Z ORP Standard 500ml (460 mV± 10 at 20°C) 2
9210342 Reference Cell Recharge, KCl Gel, 250 ml 2
9550146 O-Ring, 2-229, Viton, Shroud 2
9550147 O-ring, 2-232, Viton, Flow Cell 2
11275-00 Handrail Mounting Bracket for Submersion Service
1000857 Handrail Mounting Bracket for Submersion Service, for use with Remote Junction Box
3
Model 381+ pH/ORP SECTION 1.0
DESCRIPTION AND SPECIFICATIONS
1.3 ORDERING INFORMATION
Model 381+ pH/ORP Sensor is housed in a PES body suitable for insertion, submersion or flow through installa-
tion. The sensor includes an integral preamplifier, measuring electrode, double junction gel filled reference cell,
automatic temperature compensation, and a choice of two cable lengths, 15 ft. or 50 ft. (4.5 or 15.2 m). The Model
381+ sensor provides on line advanced diagnostic capabilities and is compatible with the Modeld 54e pH/ORP and
1055 Analyzers and Models 81, 3081, 4081, 5081, and Xmt pH/ORP Two-Wire Transmitters.
381+ – 00 – 10 – 20 – 31 – 40 – 55 EXAMPLE
MODEL 381+ INSERTION, SUBMERSION, FLOW THROUGH SENSOR
CODE LIQUID JUNCTION
20 Wood/PVDF Liquid Junction
21 Ceramic/PVDF Liquid Junction
CODE INSTALLATION
00 Insertion
02 Submersion
03 Flow Through
04 Flow Through with Flow Powered Cleaner (not available with ORP).
CODE MEASURING ELECTRODE
10 General purpose pH
11 High pH Electrode, requires Code 21. For sodium concentrations
grea
ter than 1% or
continuous
measurement above 11 pH.
12 Ruggedized pH Electrode. For abrasive solutions.
13 Platinum ORP Electrode
14 Gold ORP Electrode
15 HF pH Electrode. For HF concentrations less than 100 ppm.
CODE TEMPERATURE COMPENSATION
31 Automatic T.C., 100 ohm RTD.
CODE INTEGRAL PREAMPLIFIER
52 Preamp NOT REQUIRED
55 Preamp for Model 54, 54e, 1055, 81, 3081, 4081, 5081-P, and Xmt-P
CODE CABLE
40 15 ft. (4.5 m) cable for integral sensor preamp
41 15 ft. (4.5 m) coax cable for remote preamp (requires Code 52)
43 50 ft. (15.2 m) cable for integral sensor preamp
4
MODEL 381+pH/ORP SECTION 2.0
INSTALLATION
SECTION 2.0
INSTALLATION
2.1 INSTALLATION. Prepare the sensor for instal la tion
as follows (see Figure 2-1):
1. Remove the cover from the body by grasping the
body and rotating the cover 1/4-turn counter
clockwise.
2. When the cover breaks loose from the body, pull
the cover straight out.
3. Lubricate the seals of the glass electrode with Oring lubricant, Rosemount Analytical P/N 2001928,
and install the glass electrode in the body. Tighten
the electrode nut by hand. DO NOT use tools.
CAUTION
Do not get lubricant on tip of glass or metal
electrode. It will disrupt the electrical circuit
path.
4. Make sure the double junction electrode is threaded tightly.
5. Plug the preamplifier (or remote connector) onto
the T.C. solution ground and microjunction reference electrode pins.
6. Connect the BNC connector from the glass elec trode to the preamplifier (or remote connector).
7. Install the body O-rings. Make sure they are clean,
and not twisted. Make sure the covers mating surfaces faces are clean.
8. Lubricate the body O-rings with O-ring lubricant,
P/N 2001928.
9. Plug the cable connector to the preamplifier, making
sure the cable is toward the center of the body.
10. Install the cover on the body so that the threads
will engage.
11. Rotate the cover until the triangle on the body
aligns with (or falls within) the adjacent mark on
the cover.
12. While holding the sensor in an upright position
(see Figure 2-1), remove the 1/4-inch shipping
plug from the electrode tip end of the sensor.
13. Install the liquid junction in place of the 1/4-inch plug,
using TEFLON tape on the liquid junction threads.
CAUTION
DO NOT use pipe joint compound or pipe
dope on the threads of the liquid junction.
The electrical circuit will be disrupted if the
liquid junction is contaminated.
2.2 SUBMERSION INSTALLATION (Code 02). To
install the sensor in process proceed as follows (see
Figure 2-2):
1. Wrap TEFLON tape on 3/4-inch MNPT threads of
cover and on standpipe threads.
CAUTION
Do not use a pipe wrench on the plastic
parts. Severe damage could result.
2. Attach a 3/4-inch coupling to the sensor.
3. Attach electrode shroud to 2 inch MNPT.
4. Feed cable through the rigid standpipe.
5. Attach the rigid standpipe to the coupling.
CAUTION
Rigid standpipe should be water-tight.
6. Tighten all fittings and secure the standpipe to
minimize sensor movement. Use flexible conduit
at the top of the rigid standpipe to permit removal
of the sensor for periodic maintenance.
7. Refer to Section 2.6 and wire the sensor to the
transmitter as described.
2.3 INSERTION INSTALLATION (Code 00). To install
the sensor in the side of a tank, in a pipeline, or in a
pipe “tee”, proceed as follows (see Figure 2-3):
CAUTION
Sensor must be installed within 80° of the
vertical plane.
1. Use TEFLON tape on pipe joint, and install sensor
as shown in Figure 2-3.
CAUTION
Do not use a pipe wrench on the plastic
sensor parts. Severe damage could result.
2. Tighten all fittings and sensor.
3. Refer to Section 2.6 for wiring instructions.
4. If desired, the cable may be installed in a con-duit.
Flexible conduit MUST be used at the sensor for a
short distance to permit removal for periodic maintenance. Use the 3/4-inch MNPT threads on the
cover to attach the conduit to the sensor.
5
MODEL 381+pH/ORP SECTION 2.0
INSTALLATION
FIGURE 2-1. Sensor Component Locator Diagram
DWG. NO. REV.
40381+04 B
MILLIMETER
INCH
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