Product Data Sheet
PDS 71-381/rev.A
September 1999 Model 381 pH/ORP
Insertion/Submersion Flow Through Sensor
• ADVANCED ON-LINE SENSOR DIAGNOSTICS1
(Model 381+ only), for use with the Model
54pH/ORP Analyzer and 3081pH/ORP Transmitter,
predict and identify process-related sensor failures.
• MODULAR DESIGN facilitates maintenance by
eliminating terminal and mounting brackets and
extraneous hardware.
• DOUBLE-JUNCTION, GEL-FILLED REFERENCE
CELL provides high temperature performance,
extended service life, and resistance to the effects
of pumping, dilution, and contamination.
• MOLDED POLYETHERSULFONE (PES) BODY
provides compatibility with a variety of processes.
• OPTIONAL FLOW-POWERED OR ULTRASONIC
CLEANING provides trouble-free service in difficult
applications.
FEATURES AND APPLICATIONS
The Rosemount Analytical Model 381 Sensor meas- The modular body design eliminates the need for
ures the pH or the Oxidation Reduction Potential internal mounting brackets, terminal brackets, and
(ORP) of aqueous solutions in pipelines, open tanks, or screws. All components are screw-type or plug-in-
ponds. The sensor is suitable for use in most industrial place, allowing for fast simple service.
applications, including water and waste treatment The integral preamplifier conditions the high imped-
plants. ance glass electrode signal at the sensor, providing a
The Model 381 is available with an optional stainless transmission capability of up to 1000 ft (304.8 m). The
steel solution ground. The solution ground provides Rosemount Analytical method of preamplification has
advanced sensor diagnostics for preventative mainte- become the industry standard for reliable pH meas-
nance when used with the Models 54pH/ORP urement. In submersion applications at temperatures
Analyzer and 3081pH/ORP Transmitter. Sensor diag- greater than 80°C, the preamplifier must be located in
nostics result in time and money savings by reducing a remote junction box or in the instrument.
the guesswork in sensor maintenance and replace- A double-junction, gel-filled reference cell, a stan-
ment requirements. dard feature of the Model 381, improves sensor life
The sensor is housed in a molded PES body and has when unknown reference cell contaminants, such
two O-ring seals with breach lock threads that secure as sulfides, may exist. The gel solution maintains its
the PES cover. This provides a waterproof union for viscosity at high temperatures, and resists the effect
long operating life and easy removal for routine main- of pumping and dilution, resulting in an extended
tenance.
Continued on page 2
FEATURES AND APPLICATIONS
Continued from page 1
service life. A choice of a wood or ceramic liquid junc- fluid in a circular path carrying three Teflon2 balls that
tion allows the user to optimize performance by clean the electrode surface, physically preventing
emphasizing reference life (wood) or chemical resist- accumulation of coating materials. Flow-powered
ance (ceramic). cleaning is suitable for all hazardous area applica-
In many flow applications, crystalline or viscous coat- tions.
ings are present, such as calcium carbonate or petro- The Model 381 is available with 3K Balco or Pt 100
leum oils, which may coat the electrode surfaces and temperature compensation and is compatible with all
impede the sensor’s performance. The flow-powered Rosemount Analytical pH/ORP Analyzers.
cleaning option may be used in these instances. A 1
Patent pending
specially designed flow chamber directs the process 2
Teflon is a registered trademark of E.I. du Pont de Nemours & Company.
SPECIFICATIONS
Materials of Construction:
Body, Cover and Flow Cell: Polyethersulfone (PES) Minimum Conductivity: 75 µS/cm, nominal 100 µS/cm
O-Rings: Viton3 Temperature Compensation: Automatic, 0 to 100°C
(32 to 212°F)
Measuring Electrode: Glass (and platinum or gold
for Model 381 ORP) Maximum Pressure/Temperature Rating:
790 kPa (abs) at 100°C (100 psig at 212°F)
Liquid Junction: Kynar4/wood (Code 20) or
Kynar/ceramic (Code 21) Cable: For Code pH, pHE, ORP: 4 conductor, 22 GA
with common shield. Code +: 10 conductor,
Solution Ground: 316 Stainless steel (Code + only) shielded cable
Sensor Process Connections: Weight/Shipping Weight: 1.0 kg/1.7 kg (2.2 lb/3.7lb)
Submersion: 3/4 in. MNPT
3
Viton is a registered trademark of E.I. du Pont de Nemours & Co.
Insertion: 2 in. MNPT 4
Kynar is a trademark of Elf Atochem North America, Inc .
Flow Through Cell: 3/4 in. MNPT inlet and outlet 5
A CCU G LASS is a trademark of Rosemount Analytical.
Measuring Ranges:
ORP; -1500 to +1500 mV
pH; ACCUGLASS™5 0-14
Percent Linearity Over pH Range
General Purpose and Ruggedized glass (codes -10 &-12) High pH glass (code -11)
0-2 pH 97% 94%
2-12 pH 99% 97%
12-13 pH 96% 98%
13-14 pH 92% 98%
* Note: Ruggedized glass electrodes are ideal for abrasive applications, but response times are typically slower than other glass
formulas.
2 Rosemount Analytical
MOUNTING AND DIMENSIONAL DRAWING
MILLIMETER
INCH
CABLE 4.5 IN.
CORD GRIP 15 FT.
(DO NOT REMOVE)
9.5
3/8
3/4” MNPT
COVER
249.2
8-13/16
BODY
2 IN. MNPT
(FOR INSERTION
INSTALLATION)
48.4
1-28/32
47.6
1-7/8 DIA
81.7
3-7/32 DIA
MEASURING
ELECTRODE TEMPERATURE
COMPENSATOR1
LIQUID JUNCTION
1 ALSO SERVES AS SOLUTION GROUND FOR 381+
INSERTION AND FLOW THROUGH INSTALLATION
10°
MIN
2 IN.
MNPT
2 IN. MNPT
PIPE TEE
INSTALLATION SIDE OF TANK
STRAIGHT INSTALLATION
FLOW FLOW
3/4 IN.
MNPT
10°
MIN
2 IN. MNPT
WELD 150 LBS. RAISED
2 IN. GASKET FACE FLANGE
MNPT PIPE LINE
INSTALLATION
FLOW
PIPE TEE INSTALLATION
ELBOW FLOW
FLOW
Rosemount Analytical 3
SUBMERSION INSTALLATION: HANDRAIL MOUNTING ACCESSORY (P/N 1000857)
4 Rosemount Analytical
MILLIMETER
INCH
SUBMERSION INSTALLATION: HANDRAIL MOUNTING ACCESSORY (P/N 11275-00)
Rosemount Analytical 5
MILLIMETER
INCH MODEL 381 SENSOR IN
FLOW THROUGH ASSEMBLY
MODEL 381 SENSOR WITH FLOW
POWERED CLEANER, MINIMUM FLOW
RATE REQUIRED IS 2 gpm;
DO NOT EXCEED 6 gpm AS THIS
COULD CAUSE ELECTRODE DAMAGE.
6 Rosemount Analytical
ORDERING INFORMATION
Model 381 pH/ORP Sensor is housed in a PES body suitable for insertion, submersion, or flow through
installation. The sensor is offered with an integral preamplifier, measuring electrode, double-junction gel-filled
reference cell, automatic temperature compensation for pH, and a choice of two cable lengths of either
15 ft or 50 ft (4.5 or 15.2 m).
MODEL
381 INSERTION, SUBMERSION, FLOW THROUGH SENSOR
CODE FUNCTION
pH pH assembly for Models 1003, 1023, 1050, 1060, and 1181pH; requires Code 30
pE pH or ORP assembly for Models 1054, 1054A, 1054B, 2054, and 2081; requires Code 31
+ pH or ORP assembly for Models 54, 81, 3081, 4081 pH or ORP; requires Code 31
OR ORP assembly for Models 1003, 1023, 1050, 1060, and 1181ORP; requires Code 32
CODE INSTALLATION
00 Insertion, 2 in. MNPT
02 Submersion, 3/4 in. MNPT
03 Flow Through Assembly, 3/4 in. MNPT inlet and outlet
04 Flow Through Assembly with Flow Powered Cleaner (not available with ORP), 3/4 in. MNPT inlet and outlet
CODE MEASURING ELECTRODE
10 General purpose pH, GPHT (0-14), not available with Code OR
11 High pH Electrode, requires Code 21. For sodium concentrations greater than 1 or continuous
measurement above 11 pH; not available with Code OR
12 Ruggedized pH Electrode. For abrasive solutions, not available with Code OR
13 Platinum ORP Electrode, not available with Code pH
14 Gold ORP Electrode, not available with Code pH
15 HF pH Electrode. For HF concentrations less than 300 ppm, not available with Code OR
CODE LIQUID JUNCTION
20 Wood/Kynar Liquid Junction
21 Ceramic/Kynar Liquid Junction
CODE TEMPERATURE COMPENSATION
30 Automatic TC, 3K ohm. For Models 1003, 1023, 1050, 1060, & 1181pH
31 Automatic TC Pt 100, 100 ohm RTD. For Models 1054, 1054A, 1054B, 2054, 2081, 54, 81, 3081, and 4081
32 Automatic TC NOT REQUIRED. For Models 1003, 1023, 1050, 1060, & 1181 ORP
CODE CABLE
40 15 ft (4.5 m) cable for integral sensor preamp (see below for preamp choices)
41 15 ft (4.5 m) coax cable w/BNC connector for remote sensor preamp and integral analyzer preamp
(Models 1054A-54, 1054B-54, 2054-54 only)
42 15 ft (4.5 m) coax cable w/o BNC connector for integral analyzer preamp (Models 1054, 1181-43/44, and
2081-05 only), not available with Codes OR and +
43 50 ft (15.2 m) cable for integral sensor preamp (see below for preamp choices)
CODE INTEGRAL PREAMPLIFIER
50 Preamp for Models 1181 pH/ORP & 1050/1060
51 Preamp for Models 1003/1023
52 Preamp NOT REQUIRED (uses Code 41 or 42 only)
54 Preamp for Models 1054, 1054A, 1054B, 2054, and 2081
55 Preamp for Models 54, 81, 3081, and 4081 (for Code+ only)
381 pH 00 10 20 30 40 50 EXAMPLE
NOTE: Model 2700 Analyzer can be used only with Models 381+-31/33-45-52.
Rosemount Analytical 7
MODEL 381 pH, pHE, ORP ACCESSORIES
PART # DESCRIPTION
1000856 Handrail mounting bracket for submersion service, for use with Models 1003 & 1023
1000857 Handrail mounting bracket for submersion service, for use with remote junction box
22697-00 Combination pH electrode, general purpose
22697-01 Combination pH electrode, high pH
22698-00 Preamplifier for use with Models 1003, 1023
22698-02 Preamplifier for use with Models 1050, 1181
22698-03 Preamplifier for use with Models 1054/2054 Series, 2081
22719-02 Remote junction box
22811-00 Flow cell (includes electrode shroud)
22892-00 Flow powered cleaner retrofit kit (for use with Option -03 sensors)
22996-00 Remote junction box for internal preamp
23296-00 Remote Division 2 junction box for internal preamp for use with Models 1181pH/ORP,
1050/1060, 1003/1023
23296-01 Remote Division 2 junction box for internal preamp for use with Models 1054/2054 Series, 2081
9200160 Extension cable, sensor or remote preamp to analyzer, specify length
MODEL 381+ ACCESSORIES
PART # DESCRIPTION
11275-00 Handrail mounting bracket for submersion service
1000857 Handrail mounting bracket for submersion service, for use with remote junction box
22892-00 Flow powered cleaner retrofit kit (for use with option -03 sensors)
23550-00 Junction Box, with extension board 54, 81, 3081, and 4081 compatible
23646-01 Extension cable, double shield, prepped, specify length, for option -40 and -43
23555-00 Remote junction box with preamp for 54, 81, 3081, and 4081 compatible, for option -40 and -43
23557-00 Preamplifier for junction box, 54, 81, 3081, and 4081 compatible
9200273 Extension cable, 10 conductor, shielded, unprepped, specify length
The right people,
the right answers,
right now.
ON-LINE ORDERING NOW AVAILABLE ON OUR WEB SITE
http://www.raihome.com
Credit Cards for U.S. Purchases Only.
Emerson Process Management
Rosemount Analytical Inc.
2400 Barranca Parkway
Irvine, CA 92606 USA
Tel: (949) 757-8500
Fax: (949) 474-7250
http://www.raihome.com
© Rosemount Analytical Inc. 2003
