• ADVANCED ON-LINE SENSOR DIAGNOSTICS
(Model 381+ only), for use with the Models 54e
pH/ORP and 1055 Analyzers and 81, 3081, 4081,
5081-P, and Xmt-P pH/ORP Transmitters, 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 CLEANING provides
trouble-free service in difficult applications.
Model 381 pH/ORP
Insertion/Submersion Flow Through Sensor
Product Data Sheet
PDS 71-381/rev.E
October 2010
Continued on page 2
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 suitable for use in most indus trial
applications, including water and waste treatment
plants.
The Model 381+ features a stainless steel solution
ground. The solution ground provides advanced sensor diagnostics for preventative maintenance when
used with the Models 54e pH/ORP and 1055 analyzers and 81, 3081, 4081, 5081-P, and Xmt-P pH/ORP
transmitters. Sensor diagnostics result in time and
money savings by reducing the guesswork in sensor
maintenance and replacement requirements.
The sensor is housed in a molded PES body and has
two O-ring seals with breach lock threads that 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-inplace, 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 ft (304.8 m). The
Rosemount Analytical method of preampli fication has
become the industry standard for reliable pH measurement. In submersion applications 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
2 Rosemount Analytical
FEATURES AND APPLICATIONS
Continued from page 1
service life. A choice of a wood or ceramic liquid junction allows the user to optimize performance by
emphasizing reference life (wood) or chemical resistance (ceramic).
In many flow applications, crystalline or viscous coatings are present, such as calcium carbonate or petroleum oils, which may coat the electrode surfaces and
impede the sensor’s performance. The flow-powered
cleaning option may be used in these instances. A
specially designed flow chamber directs the process
fluid in a circular path carrying three Teflon1balls that
clean the electrode surface, physically preventing
accumulation of coating materials. Flow-powered
cleaning is suitable for all hazardous area applications.
The Model 381 is available with 3K Balco or Pt 100
temperature compensation and is compatible with all
Rosemount Analytical pH/ORP Analyzers.
1
Teflon is a registered trademark of E.I. du Pont de Nemours & Company.
SPECIFICATIONS
Materials of Construction:
Body, Cover and Flow Cell: Polyethersulfone (PES)
O-Rings: Viton
2
Measuring Electrode: Glass (and platinum or gold
for Model 381 ORP)
Liquid Junction: Kynar3/wood (Code 20) or
Kynar/ceramic (Code 21)
Solution Ground: 316 Stainless steel (Code + only)
Sensor Process Connections:
Submersion: 3/4 in. MNPT
Insertion: 2 in. MNPT
Flow Through Cell: 3/4 in. MNPT inlet and outlet
Measuring Ranges:
ORP; -1500 to +1500 mV
pH; ACCUGLASS
™
4
0-14
Minimum Conductivity: 75 μS/cm, nominal 100 μS/cm
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: For Code pH, pHE, ORP: 4 conductor, 22 GA
with common shield. Code +: 10 conductor,
shielded cable
Weight/Shipping Weight: 1.0 kg/1.7 kg (2.2 lb/3.7lb)
2
Viton is a registered trademark of E.I. du Pont de Nemours & Co.
3
Kynar is a trademark of Elf Atochem North America, Inc.
4
ACCUG LASS is a trademark of Rosemount Analytical.
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.
MOUNTING AND DIMENSIONAL DRAWING
INSERTION AND FLOW THROUGH INSTALLATION
PIPE TEE
INSTALLATION
STRAIGHT
FLOW
SIDE OF TANK
INSTALLATION
PIPE TEE INSTALLATION
ELBOW FLOW
GASKET
WELD
150 LBS. RAISED
FACE FLANGE
PIPE LINE
INSTALLATION
2 IN. MNPT
2 IN. MNPT
2 IN.
MNPT
2 IN.
MNPT
3/4 IN.
MNPT
10°
MIN
FLOW
FLOW
FLOW
10°
MIN
CABLE
3/4” MNPT
COVER
BODY
2 IN. MNPT
(FOR INSERTION
INSTALLATION)
4.5 IN.
15 FT.
249.2
8-13/16
48.4
1-28/32
47.6
1-7/8 DIA
81.7
3-7/32 DIA
CORD GRIP
(DO NOT REMOVE)
MEASURING
ELECTRODE
TEMPERATURE
COMPENSATOR
1
LIQUID JUNCTION
9.5
3/8
1
ALSO SERVES AS SOLUTION GROUND FOR 381+
Rosemount Analytical 3
MILLIMETER
INCH
SUBMERSION INSTALLATION: HANDRAIL MOUNTING ACCESSORY (P/N 1000857)
4 Rosemount Analytical
SUBMERSION INSTALLATION: HANDRAIL MOUNTING ACCESSORY (P/N 11275-00)
MILLIMETER
INCH
Rosemount Analytical 5
6 Rosemount Analytical
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.
MILLIMETER
INCH
MODEL 381 SENSOR IN
FLOW THROUGH ASSEMBLY
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).
Level 4 LIQUID JUNCTION
20 Wood/Kynar Liquid Junction
21 Ceramic/Kynar Liquid Junction
Level 6 INSTALLATION
_ No Selection
02 Submersion
03 Flow Through
04 Flow Through with Flow Powered Cleaner
Level 1 TEMPERATURE COMPENSATOR
31 Automatic TC, 100 ohm RTD
Level 3 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
Level 5 PREAMPLIFIER
52 Preamp NOT REQUIRED
55 Preamp for Models 54/e, 81, 3081, 4081, 5081-P, and Xmt-P (for Code+ only)
Level 7 SPECIAL
_ No Selection
99 Special (consult factory)
Level 2 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 and 54e, 1055, 81, 3081, 4081, 5081-P, and Xmt-P)
43 50 ft (15.2 m) cable for integral sensor preamp (see below for preamp choices)
Level 0 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 54/54e, 1055, 81, 3081, 4081, 5081-P, Xmt-P; requires Code 31
OR ORP assembly for Models 1003, 1023, 1050, 1060, and 1181ORP; requires Code 32
MODEL
381 INSERTION, SUBMERSION, FLOW THROUGH SENSOR
Rosemount Analytical 7
PART # DESCRIPTION
23550-00 Junction Box, with extension board 54, 81, 3081, and 4081 compatible
23555-00 Remote junction box with preamp for 54/e, 5081-P, and Xmt-P compatible
23557-00 Preamplifier for junction box, 54/e, 5081-P, and Xmt-P compatible
9210012 Buffer Solution, pH 4.01, 16 oz.
9210013 Buffer Solution, pH 6.86, 16 oz.
ACCESSORIES
PART # DESCRIPTION
2000734 Liquid Junction, KYNAR/wood
2000735 Liquid Junction, KYNAR/Ceramic
22694-00 Electrode, pH, GP
22694-01 Electrode, High pH
22694-02 Electrode,pH, Rugged
22694-03 Electrode, pH, HF Resistant
22697-00 Electrode, Combination pH
22697-01 Electrode, HIgh pH, Combination
22723-00 Flow Powered Cleaner Balls (quantity 9)
22731-00 ORP Electrode, Platinum
22751-00 O-ring Kit (quantity 5), Upper Body
22751-01 O-ring Kit (quanity 5), Lower Body
22811-01 Flow Powered Cleaner - Retrofit Kit, code -00, -02
22892-00 Flow powered cleaner retrofit kit (for use with Option -03 sensors)
23018-00 Reference element (formerly 22688-00)
23551-00 Sensor Body, complete, Pt-100
23552-00 Sensor Cover with 15’ Cable
23552-01 Sensor Cover with 15’ Coax Cable
23552-02 Sensor Dover with 50’ Cable
32602-00 Flow Cell, PES
32605-00 Electrode, Shroud, Protective
32606-00 Flow Cell Coupling Nut, PES
32793-00 Flow Powered Cleaner, Ring
SPARE PARTS
Credit Cards for U.S. Purchases Only.
The right people,
the right answers,
right now.
ON-LINE ORDERING NOW AVAILABLE ON OUR WEB SITE
http://www.raihome.com
Specifications subject to change without notice.
Emerson Process Management
2400 Barranca Parkway
Irvine, CA 92606 USA
Tel: (949) 757-8500
Fax: (949) 474-7250
http://www.raihome.com
© Rosemount Analytical Inc. 2010
8
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