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Signet 2744-2747 Di erential DryLoc®
pH/ORP Electrodes
High Performance
Protected
Bulb
The Signet 2744-2747 Differential pH and ORP
electrodes are high performance sensors built with the
DryLoc® connector, a Ryton® body, and PTFE reference
junction to handle the most extreme and harshest of
chemical applications.
These differential electrodes use a field-proven
3-electrode differential technique: the pH and reference
electrodes are measured against a ground electrode,
ensuring a steady and stable signal.
Flat
Glass
Features
• Di erential design for stable measurements in
the most aggressive applications
• Long service life even in severe or di cult
chemical applications
• Memory chip enabled for access to a wide range
of unique features when connected to the Signet
2751 pH/ORP Smart Sensor Electronics
• High performance glass that can withstand
high pH caustic media as well as elevated
temperature applications
• Ryton (PPS) body for broad range of chemical
compatibility
• Watertight DryLoc® connector with foul-proof
gold plated contacts*
• Porous PTFE reference junction resists fouling
and chemical attack
• Rebuildable reference electrode
• Solution ground
• Temperature sensor (pH)
A key feature is the reference electrode, which is housed
in a glass half-cell embedded in the reference chamber
and is protected from compounds that may contain
sulfides (S2-) and metals. To ensure long service life,
the reference features a refillable electrolyte chamber
and a replaceable equitransferant salt bridge, both
easily serviced in the field. The patented porous PTFE
reference junction resists fouling, clogging and chemical
attack.
Other elements of the design are the solution ground,
the pH/ORP electrodes, and the temperature element.
The solution ground eliminates noisy measurements
by draining electrical current away from the reference
electrode. The pH/ORP electrodes are designed with a
flat or bulb surface, and a temperature device positioned
at the tip of the measurement surface for a quick
temperature response. Various temperature devices
offered include 3 KΩ or Pt1000 RTD.
The electrodes are used with the Signet 2751 Smart
Sensor Electronics, which provide a blind 4 to 20 mA
output or use the digital (S3L) output to connect the
Signet 8900, 9900 or 9950 instruments, and the
0486 Profibus Concentrator. The electrodes can also be
used with the 2760 Preamplifier to connect to ProPoint®
and ProcessPro® series of pH/ORP instrumentation.
• Easy sensor replacement using DryLoc
electrode connector
• Quick temperature response
• Compatible with all Signet instruments
Applications
• Plating Baths
• Surface Finishing
• Plant E uent
• Water and Wastewater Treatment
• Scrubbers
• Textile Dye Process
• Harsh Chemical Applications
• Heavy Metal Removal and Recovery
• Toxic Destruction
• Coagulation and Flocculation
See Technical Reference section for assistance in choosing
the correct sensor.
*U.S. Patent No.: 6,666,701
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Specifi cations
General
Compatibility Signet 2751 and 2760
Operating Range 2744/2746 0 to 14 pH
2745/2747 ±1500 mV (ORP)
Process Connection 1 in., for use in reducing tees up to 4 in.
Wetted Materials
Body Ryton®
Reference Junctions PTFE
Sensing Surface pH Glass membrane
ORP Platinum
O-rings EPDM
Solution Ground Carbon graphite
Max. Temperature/Pressure Rating
Operating Temperature Range 10 °C to 100 °C 50 °F to 212 °F
Operating Pressure Range 0 to 6.9 bar (0 to 100 psi) @ 10 °C to 65 °C (50 °F to 149 °F)
Linearity Derated 6.9 to 4.0 bar (100 to 58 psi) @ 65 °C to 100 °C (149 °F to 212 °F)
Recommended Storage Temperature
0 °C to 50 °C 32 °F to 122 °F
The electrode glass will shatter if shipped or stored at temperatures below 0 °C (32 °F).
The performance life of the electrode will shorten if stored at temperatures above 50 °C (122 °F).
Mounting
In-line/Vertical Mounting Use sensor 1 in. threads. Sensor must be mounted at least 15 degrees above
the horizontal axis.
Submersible Mounting Use threads on Model 2751 or 2760; requires ¾ in. NPT or ISO 7/1-R 3/4 male
threaded extension.
Reference
Electrolyte Bu ered equi-transferant salt solution gel
Element pH half-cell
Temperature Sensor pH 3 KΩ, Pt1000 RTD
ORP 10K ID Resistor
Shipping Weight
0.25 kg 0.55 lb
Standards & Approvals
Manufactured under ISO 9001, 14001 and OHSAS 18001 for Quality
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Dimensions
38.6 mm
(1.52 in.)
35.6mm
(1.4 in.)
32.5 mm
(1.28 in.)
133.8 mm
(5.27 in.)
1 in.
NPT
25.4 mm
(1.0 in.)
Flat and Bulb versions
have the same dimensions
28.7 mm
(1.13 in.)
0.63 mm
(0.25 in.)
insertion
depth,
typical
System Overview
Panel Mount Pipe, Tank, Wall 4 to 20 mA Output Automation System
Signet Instruments
with 2751 Smart Sensor
Electronics
- 8900
- 9900
- 9950
ENTER
Signet 2744-2747
DryLoc® pH/ORP
Electrodes
In-Line Installation threaded fi ttings only
Signet Instruments
with 2751 Smart Sensor Electronics
- 9900 and Rear Enclosure
+
2751 Smart Sensor Electronics with
- Customer Supplied Chart Recorder
Programmable Logic Controller, or
- Programmable Automation Controller
+
Submersible Installation Customer supplied pipe extension
or conduit with 3/4 in. NPT or ISO 7/1-R 3/4
threads*
PLC
2751 Smart Sensor Electronics with
- 0486 Profi bus Concentrator and
Customer Supplied Programmable Logic
Controller or
- Programmable Automation Controller
L IN+
L IN-
N/C
L OUT+
L OUT-
N/C
L IN+
L IN-
+5V OUT
DATA
GND
L IN+
L IN-
+5V OUT
DATA
GND
Out
In
S3LLoop
S3LLoop
USB
Profibus
Channel 5
Channel 6Channel 7
Valve
Signet 3-0486 Profibus Concentrator
+
Address
Power
Channel 1
24 VDC
0.40A Max
S3LFreq
+5V OUT
Freq IN
PWR+
PWR+
PWR+
PWR-
PWR-
PWR-
+
Channel 2
Channel 3
Channel 4
S3LFreq
S3LFreq
S3LFreq
+5V OUT
+5V OUT
+5V OUT
Freq IN
Freq IN
Freq IN
DATA
DATA
DATA
DATA
GND
GND
GND
GND
All sold separately
PLC
*Refer to the Signet Submersion Kit brochure (3-0000.707) located on our website for installation suggestions and options.
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Electrode Key Features and Benefi ts
1. Glass encased reference electrode protects the Ag/AgCl (silver/silver
chloride) element from reacting with certain chemical compounds that
typically leach into the reference chambers. Keeps the pH/ORP reading
stable.
2. Large volume reference electrolyte chamber resists dilution over time for
a long service life. Chamber is refi llable. Holds approximately 30 ml of
electrolyte.
3. Salt Bridge serves as a double reference junction and is the fi rst line of
defense to keep out process chemicals from the reference electrolyte
chamber. It is built with a double porous PTFE reference junction which is
highly compatible to chemicals, resists fouling and build-up of dirt.
4. Memory chip enabled for convenient data storage and access (calibration
data, operational data, and manufacturing data), electrode health
monitoring via glass impedance measurement when used in connection
with the 2751 pH/ORP Smart Sensor Electronics.
5. Ryton® body for chemical compatibility to most harsh chemicals. Also able
to withstand high temperatures.
6. DryLoc connector with corrosion resistant gold plated pins for quick and
easy sensor removal.
7. Capillary TC (temperature sensor) embedded in tip of pH/ORP electrode for
quick temperature response.
8. Measuring pH/ORP electrode.
6
4
1
5
2
3
7
8
9. Solution Ground electrode eliminates noisy measurements by draining
electrical current away from the reference electrode.
9
Electrode Cut-Away View
A di erential electrode solves many common problems typically experienced by standard pH/ORP electrodes at troublesome
measuring points. See the table below to fi nd the common problem, cause and e ect, and the di erential pH/ORP electrode
solution.
If the (Signet Models 272X,
273X or 277X) pH/ORP
electrode experiences
The cause and e ect of the
problem may be:
Use a Di erential Electrode to solve
the problem because:
the following:
-
• Salt bridge will slow or stop attack. If attacking
or
4
ions penetrate the salt bridge and a ect the
reference, simply refi ll reference solution.
• Readings do not drift due to stable di erential
reference design, however may require
cleaning or replacement of the salt bridge if
• Reading slowly drifts
over time
• Sensor responds slowly
• Chemical attack from Hg
2+
, Cu+, Pb2+, ClO
other compounds which react with or dilute
the KCl reference electrolyte.
• Reference junction gets clogged from oils,
grease, or dirt from the process.
electrode gets too dirty.
• Reading slowly drifts
over time
• Sensor reading becomes
erratic
• Chemical attack of the Ag
-
, CN-, and S
I
-
compounds.
2
+
reference from Br-,
• Clogged reference and slowed reading from
silver compounds forming on the inside of
the reference electrode from Ag
element reacting and precipitating Ag
AgBr, AgI, AgCN, or other silver compounds.
+
of reference
S,
2
• Will not a ect electrode due to Ag
protected in glass encased reference electrode.
• Will not a ect electrode due to Ag
protected in glass encased reference electrode.
+
element
+
element
• Reading suddenly jumps
to a new value
• Reading unexpectedly
changes
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• Stray electrical currents in the process liquid;
+
reference element picks up current and
Ag
shifts reference reading, resulting in shifted
pH reading. The Ag
+
element will eventually
become totally stripped. Process must be
properly grounded or place metal rod close to
electrode.
• Will not a ect electrode due to Ag
+
element
protected in glass encased reference electrode;
also, electrode has a built in solution ground, so
if there is a stray current, it will not be seen by
the electrode.
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Temperature/Pressure Graph
Note:
The pressure/temperature graphs are specifically
for the Signet sensor. During system design the
specifications of all components must be considered.
In the case of a metal piping system, a plastic sensor
will reduce the system specification.
Ion Ion name Ion Ion name Compound Compound name
Br-Bromide Hg2+Mercury KCI Potassium chloride
Cu+Copper iron CIO
-
Cyanide Ag+Silver AgBr Silver bromide
CN
I-Iodide S2-Sulfi de AgI Silver iodide
++
Pb
Lead AgCN Silver cyanide
-
Perchlorate Ag2S Silver sulfi de
4
Model 2744-2747
Ordering Notes
1) pH and ORP electrodes require connection to model
2751 or 2760.
2) Conduit and mounting brackets for submersible
installations must always be used (customer
supplied).
3) Adapters from 1 - 1½ in. are available.
4) Use sensor threads for in-line mounting; Model
2751 or 2760 threads for submersible mounting.
5) Reference electrode can be rebuilt with
replacement electrolyte and salt bridge.
(psi)
(bar)
10.3
150
8.6
125
6.9
100
5.2
75
3.4
50
1.7
25
0
-40
°F°C-40
-20
-4
0
32 68
20
40
60 80 100
104
140
176
212
Application Tips
• Use the fl at glass electrodes when a self-cleaning
feature is desired; especially useful in applications
with abrasive chemicals for in-line installations.
• Use bulb protected electrodes for low temperature
applications where a fast response is required.
• ORP electrodes are generally used for chemical
reaction monitoring, not control.
• Ensure sensor materials are chemically compatible
with the process liquid.
• Keep electrode tip wet, avoid air pockets and
sediment.
120
248
Bu er Solutions
3822-7004
3822-7007
3822-7010
Quinhydrone
3822-7115
The Signet pH bu ers are ideal for calibration. The
liquid solutions are conveniently packaged in one pint
(473 ml) bottles. pH bu er kits in powder pillows are
available for mixing fresh solutions with water at the
time of use.
All pH bu ers are color coded for easy identifi cation;
4.01 pH is red, 7.00 pH is yellow, and 10.00 pH is blue.
All pH bu ers are traceable to NIST standards.
The 4.01 and 7.00 pH bu er solutions can be used
to calibrate ORP sensors when saturated with
quinhydrone.
Please refer to Wiring, Installation, and Accessories sections for more information.
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Ordering Information
Mfr. Part No. Code Tip Design Temperature Element
pH Di erential Electrode
3-2744-1 159 001 944 Flat 3 K Balco
3-2744-2 159 001 910 Flat Pt1000
3-2746-1 159 001 911 Bulb with protection 3 K Balco
3-2746-2 159 001 912 Bulb with protection Pt1000 RTD
ORP Di erential Electrode
3-2745-1 159 001 913 Flat 10 K ID
3-2747-1 159 001 914 Bulb with protection 10 K ID
1
For use with the Multi-Parameter instruments, and Profi bus Concentrator when used with the 2751 Smart Sensor Electronics.
The 2751 Smart Sensor Electronics has a digital (S3L) output which is used with the Multi-Parameter instruments. It also has a
4 to 20 mA output for connections to PLC’s, data recorders, etc.
2
The 2760 preamplifi er is used for connection directly to ProPoint® and ProcessPro® series pH/ORP instrumentation.
1, 2
1
1, 2
1
1, 2
1, 2
Accessories and Replacement Parts
Mfr. Part No. Code Description
1224-0205 159 000 836 O-ring, EPDM
3-2700.395 159 001 605 Calibration kit: includes 3 polypropylene cups, box used as cup stand, 1 pint pH
4.01, 1 pint pH 7.00
3822-7115 159 001 606 20 gm bottle quinhydrone for ORP calibration (must use pH 4.01 and/or
pH 7.00 bu er solutions)
3800-4340 159 001 948 Replacement salt bridge in black
3864-0001 159 001 007 Replacement salt bridge in gray
3864-0002 159 001 008 Replacement reference electrolyte solution, 500 ml
2120-0015 159 001 009 CPVC adapter: 1.5 in. MNPT to 1 in. FNPT
2122-0015 159 001 010 PVDF adapter: 1.5 in. MNPT to 1 in. FNPT
3-0700.390 198 864 403 pH bu er kit (1 each 4, 7, 10 pH bu er in powder form, makes 50 ml of each)
3822-7004 159 001 581 pH 4 bu er solution, 1 pint (473 ml) bottle
3822-7007 159 001 582 pH 7 bu er solution, 1 pint (473 ml) bottle
3822-7010 159 001 583 pH 10 bu er solution, 1 pint (473 ml) bottle
3-2759 159 000 762 pH/ORP system tester kit for all pH instruments
3-2759.391 159 000 764 Adapter cable for use with 2751/2760
3800-5000 159 838 107 3.0M KCl storage solution for pH and ORP, 1 pint (473 ml) bottle
3-2700.398 159 001 886 O-ring lubricant kit (5 packs of Super Lube, 1cc each)
3-2744.099 Rev A (12/19)
© Georg Fischer Signet LLC
3401 Aero Jet Avenue, El Monte, CA 91731-2882 U.S.A. • Tel. (626) 571-2770 • Fax (626) 573-2057 • www.gfsignet.com • e-mail: signet.ps@georgfi scher.com
Specifi cations subject to change without notice. All rights reserved. All corporate names and trademarks stated herein are the property of their respective companies.
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