GF_pHORPSensor_2750_instr_D801
‡ SIGNET 2750 pH/ORP Sensor
3-2750.090
ENGLISH
B-8/01 English
SAFETY INSTRUCTIONS FOR IN-LINE ELECTRODE INSTALLATION
1. Do not remove from pressurized lines.
2. Do not exceed maximum temperature/pressure specifications.
3. Wear safety goggles or face shield during installation/service.
4. Do not alter product construction.
Failure to follow safety instructions may result in severe personal injury!
Description:
+GF+ SIGNET 2750 pH/ORP Sensors offer two output options:
• If provided with 12-24 VDC power, the 2750 will output a two-wire 4 to 20mA loop.
• If provided with 5 VDC power, the 2750 will output digital serial data (the format is S3L™: Signet Sensor Serial Link, a proprietary
digital output for use with +GF+ SIGNET equipment).
The 2750 automatically recognizes +GF+ SIGNET 275X pH or ORP electrodes and scales the current output for the appropriate range.
The range is factory set for full scale measurement:
4 to20 mA = 0 to 14 pH
4 to20 mA = -1000 to +2000 mV ORP.
Custom scaling is available from the factory.
Three versions are available to accommodate different application requirements:
• 2750-1
In-line installations
• 2750-2
In-line installations with Local EasyCal
• 2750-3
Submersible installations, 3/4 in. NPT threads
• 2750-4
Submersible installations, ISO 7-1/R 3/4 threads
Technical Data
Accuracy:
Temperature drift:
Resolution:
Error indication:
General
• Compatible Electrodes:
+GF+ SIGNET 275X pH/ORP Electrodes
Temperature sensor: PT1000
•
Operational Range:
pH:
0.00 to 14.00
ORP:
±2000 mV
Temp.
0°C to 85°C (32ºF to 185ºF)
•
Response Time (includes electrode response):
pH:
<6 s for 95% of change
ORP:
application dependent
Temp τ:
140 seconds (2754), 196 seconds (2756)
•
Materials:
2750-1&2 (in-line):
2750-3 (submersible):
Weight:
2750-1&2 (in-line):
2750-3 (submersible):
•
PBT (thermal plastic polyester)
CPVC
0.75 kg (1.75 lb.)
0.64 kg (1.4 lb.)
•
•
>1011Ω
0.5 s
Current output:
Power:
12 to 24 VDC ± 10% regulated, 20 mA max.
pH scale:
Fixed 4 to 20 mA, isolated, 0.00 to 14.00
(custom scaling available)
ORP scale: Fixed 4 to 20 mA, isolated, -1000 to 2000 mV
(custom scaling available, -2000 to 2000 mV)
Max Loop Resistance: 50Ω max. @ 12V
325Ω max. @ 18V
600Ω max. @ 24V
‡ SIGNET 2750 pH/ORP Sensor
S3L output:
Description:
Power:
Accuracy:
Serial ASCII, TTL level 9600 bps
5VDC ±5% regulated, 3 mA max
pH:
± 0.03 pH @ 25° C
ORP:
± 2 mV @ 25° C
Resolution: pH:
≤ 0.02 pH
ORP:
≤ 1 mV
Temp. ≤ 0.2° C
Error indication:
Temp output "+999.9"
Environmental
• Ambient Temp.:
• Storage Temp.:
• Immunity:
• Emissions:
•
Electrical
• Input Impedance:
• Output update rate:
±32µA @ 25ºC
±1µA per ºC
± 5µA
3.6 mA
-10°C to 85°C
-20°C to 85°C
EN50082-2
EN50081-1
Enclosure Rating:
2750-1&2 (in-line):
NEMA 4X/IP65
(with electrode connected)
2750-3 (submersible): NEMA 6P/IP68
(with electrode and watertight
extension pipe connected)
Standards and Approvals
• CE
• Manufactured under ISO 9001 & ISO 14001
page 1 of 8
Technical Data
Pressure/Temperature rating
(pH and ORP electrodes)
+GF+ SIGNET 2750 pH/ORP sensor
Pipe Size Range:
• 1/2” and up. Use +GF+ SIGNET installation fittings to 4 in.
• Use pipe adapters in pipes over 4 in.
• Submersion with 2750 sensor requires 3/4 in. NPT or
ISO 7-1/R 3/4 male threaded extensions
Efficiency:
Response Time:
>97% @ 25°C (77° F)
pH: < 5 s for 95% of signal change
ORP: Application dependent
Primary Functions:
2754, 2755: Flat surface resists fouling
2756, 2757: Bulb surface for general
use
2754-HF: Extended use in applications
with trace hydrofluoric acid (<2%)
2756-DI: Extended use in pure
waters (<100 µS)
2754 and 2756 pH Electrodes
Operating Range:
0 to 14 pH
Wetted Materials:
CPVC Body
Glass
FPM O-rings
Porous UHMW Polyethylene reference
junctions
pH Reference:
Electrolyte: Solidified Acrylamide Gel
3.5M KCI (2754, 2754-HF, 2756)
0.1 M KCl (2756-DI)
Element:
Ag/AgCl
Temperature Sensor:
PT-1000 (1096.8Ω = 25°C)
Response Time, τ:
140 secs. (2754), 196 secs. (2756)
BAR PSI
7 100
5
75
3
50
2
25
2754
General
Compatibility:
0 10
25
50
75
°C
32 50
77
122
167
°F
Temperature and pressure specifications
ORP electrode operating Temperature/Pressure
• 6.89 bar @ 0°C to 65ºC (100 psi @ 32° to 149° F)
• 4.00 bar @ 66ºC to 85°C (58 psi @150° to 185°F)
2756 and 2756-DI pH electrode operating Temperature/Pressure
• 6.89 bar @ 0°C to 65ºC (100 psi @ 32° to 149° F)
• 4.00 bar @ 66ºC to 85°C (58 psi @150° to 185°F)
2754 and 2754-HF pH electrode operating Temperature/Pressure
• 6.89 bar @ 10°C to 65ºC (100 psi @ 50° to 149° F)
• 4.00 bar @ 66ºC to 85°C (58 psi @150° to 185°F)
Storage Temperature:
1.3 2755/2757 ORP Electrodes
Operating Range:
-2000 to +2000 mV
Wetted Materials:
CPVC Body
Glass
FPM 0-rings
Porous UHMW Polyethylene reference
junctions
Platinum sensing surface
ORP Reference:
Solidified Acrlyamide Gel:3.5M KCL
saturated with AgCl
Element:
Ag/AgCl
> -12° C (11° F)
Cable supplied: 15 ft. 3 conductor shielded, 22 AWG. May be
extended up to 122 m (400 ft)
Submersible installation
In-Line installation
3-2754 Flat pH
3-2755 Flat ORP
3-2756 Bulb pH
3-2757 Bulb ORP
1.06 in./
27 mm
1.06 in./
27 mm
1.4 in./
35.3 mm
1.4 in./
35.3 mm
4.6 in./
116 mm
4.3 in./
109 mm
7.1 in./
181 mm
8.2 in./
208 mm
3.2 in./
81 mm
2.9 in./
74 mm
0.72 in./
18 mm
page 2 of 8
3.7 in./
94 mm
0.72 in./
18 mm
2.16 in./
55 mm
‡ SIGNET 2750 pH/ORP Sensor
2750 In-line pH Sensor Installation
•
The 2750-1 in-line sensor (without Local EasyCal) is designed for applications where electrode calibration is facilitated by remote
equipment.
•
The 2750-2 In-Line sensor includes Local EasyCal.
•
•
A +GF+ SIGNET installation fitting (1/2 in. to 4 in.) or a +GF+ SIGNET pipe adapter is required to secure the electrode in the pipe.
The +GF+ SIGNET Measurement and Instrumentation catalog offers a complete selection of fittings.
Type
Plastic tees
PVC saddles
Description
Type
• Available in 1/2 in. to 4 in. sizes
• PVC, CPVC w/solvent cement socket
• PVDF and PP w/union end fittings
Carbon steel
weldolets
• Available in 2 in. to 4 in. sizes
• Requires 1-7/16 in. hole in pipe
Iron
strap-on
saddles
• Available in 2 in. to 4 in. sizes
• Requires 1-7/16 in. hole in pipe
Description
• Available in 2 in. to 4 in. sizes
• Requires 1-7/16 in. hole in pipe
• Install by certified welder only
Carbon steel
threaded tees
• Available in 1/2 in. to 2 in. sizes
• Female NPT ends
Universal
pipe adapters
• Adapt any fitting with 1-1/4 in. outlet
• PVC, CPVC, or PVDF versions
• Specify socket or 1-1/4 inch NPT male threads
8052-1 NPT Junction box
4.2 in.
107 mm
YES
YES
3.7 in./
94 mm
30º
8050-1 Universal Junction box
NO
NO
4.2 in./
106 mm
NO
3.7 in./
94 mm
‡ SIGNET 2750 pH/ORP Sensor
•
•
Vertical (0°) position optimum
Do not install within 30º of horizontal
page 3 of 8
2750 In-line pH Sensor Assembly
1. Insert electrode into Signet installation fitting. Seat the
electrode tabs into the alignment notches in the fitting.
2. Thread the in-line retaining cap onto fitting to secure the
electrode into place. Hand-tighten the cap. DO NOT use any
tools to avoid damaging the threads.
Note:
Keep the electrical interconnection between electrode and sensor
electronics dry and clean at all times.
3. Disengage the locking ring on base of 2750 (The ring is
disengaged when the lines on the ring and body of the 2750
are not aligned.)
Unlocked
4. Place 2750 onto top of electrode and turn until the assembly
drops into position.
5. Turn locking ring 1/4 turn to secure the 2750 assembly. (The
ring is locked when the line on the ring and the line on the body
of the 2750 are aligned.)
Locked
In-Line Sensor and Electrode Removal
• To remove electronics assembly only:
Turn locking ring 1/4 turn; lift assembly straight up.
• To remove electrode from the pipe:
Remove electronics assembly, then unthread retaining cap;
pull electrode straight up.
• To remove the complete 2750 system:
Hold locking ring in place. Unthread retaining cap and pull
electrode straight up.
page 4 of 8
CAUTION!
• Do not remove the electrode from a pressurized
pipe.
• Wear appropriate protective clothing when working
with the system.
‡ SIGNET 2750 pH/ORP Sensor
2750-3 Submersible pH Sensor Assembly and Installation
1. Insert electrode into
base of the 2750-3
and turn until keyed
contacts are seated.
2. Thread retaining cap over electrode
and hand-tighten onto 2750.
3. Attach 3/4 in. watertight pipe to the top of the 2750.
Secure the threaded connection to prevent any leakage.
•
3/4 in. NPT threads
or ISO 7-1/R 3/4 threads
For additional defense against possible accumulation of
condensation at the back seal area of the sensor, fill the
lower 3-4 inches (75-100 mm) of conduit or extension
pipe with a flexible sealant such as silicone.
A light coat of non-petroluem
based lubricant on the o-ring with
will ease installation.
Fill with
3 to 4 in.
of sealant
Note:
Keep the electrical interconnection between electrode
and sensor electronics dry and clean at all times.
OR
Use standard installation
hardware to connect the
submersible 2750-3 directly
to external equipment.
The 8052 NPT Mount Junction box (or
8052-2 with Local EasyCal) connects to
3/4 in. pipe or conduit and provides
convenient wiring termination.
OR
The 8050 Universal Mount junction
box (or 8050-2 with Local EasyCal)
mounts flat onto a wall or can be
strapped to a post or pipe.
1/2 in. NPT threads
Fill with
3 to 4 in.
of sealant
‡ SIGNET 2750 pH/ORP Sensor
page 5 of 8
Wiring the submersible 2750 direct to external equipment
Wiring the submersible 2750 with a junction box
Use the wiring diagram below for systems without a +GF+
SIGNET junction box.
+GF+ SIGNET junction boxes include a terminal block inside the
yellow cover.
SW1
Out to external equipment
SW2
+
Cal
For Loop output, use 2 cond w/shield, 22-24 AWG
For S3L output, use 3 cond w/shield, 22-24 AWG
Run
•
•
BLK
RED
Output to
external equipment
BLK
Terminal
block label
+
RED
4-20 mA Output
Function
S
SHLD
Input from 2750
S3L Output
Function
Loop + (12-24 VDC)
V+ (5 VDC ±1%)
No connection
Data Out/Calibrate
WHT
-
Loop -
Signal Ground
SHLD
S
Earth Ground
Earth Ground
SW1
+
SW2
Cal
2750 wire
color
WHT
Run
Fill with
3 to 4 in.
of sealant
-
D1
BLK
D1
RED
Output to
external equipment
-
WHT
S
SHLD
The sensor input for the in-line
2750 is factory-connected
Wiring the in-line 2750
page 6 of 8
‡ SIGNET 2750 pH/ORP Sensor
Calibration
The 2750 pH/ORP Sensor is factory calibrated for out-of-the-box accuracy when used with new +GF+ SIGNET 275x pH and ORP
electrodes. Once in service, periodic cleaning and calibration is necessary to compensate for changes in electrode output as a result of
coating and aging. The required frequency is application-dependent, but once/week for cleaning and twice/month for calibration is good
for a start.
SW2
+
SW1
SW2
D1
Cal
SW1
Run
The 2750 pH/ORP Sensor can also be used as a blind transmitter (provides 4 to 20 mA output but has no local display of pH or ORP
value) so Local EasyCal is available as an option to facilitate calibration in the field. This accessory includes a single push-button and an
LED, which are located beneath the yellow cap inside the conduit adapter or junction box. There is also a two-position switch, labeled
“Run” and “Cal”. This switch must be in the “Run” position during normal operation and during calibration if the 4 to 20mA output of the
2750 is being utilized. If the S3L output is being used, and if the operator chooses to perform system calibrations using the Local EasyCal
accessory, then the switch must be placed in the “Cal” position during calibration only. Return the switch to the “Run” position once
calibration is complete.
BLK
Local EasyCal button
RUN/CALIBRATE switch for S3L system
Local EasyCal Indicator (green LED)
D1
RED
Calibration Tips:
• As electrodes age their reaction time becomes slower. And if there is no local display of the measured values to help the operator
determine whether an electrode’s output is settled enough for calibration, it may be prudent to allow extra time before and between
the steps of the procedure below. For example, changing temperatures can have a significant effect on electrode output, so it is
recommended to perform calibration at room temperature. Therefore, the operator should allow enough time for an electrode coming
out of a hot or cold process to achieve room temperature prior to calibration. This could take several minutes, depending on
temperature, and should be done in tap water.
• Some suitable cleaning agents such as 5% HCl or even dishwashing detergent can temporarily “shock” an electrode. It is good
practice to rinse an electrode thoroughly after each cleaning and then allow it to soak in a calibration solution or tap water for several
minutes prior to calibration.
• The electrical interconnection between electrode and sensor electronics must remain dry and clean at all times.
Local EasyCal Calibration Procedure:
The first step (Reset) is recommended each time an electrode is replaced, but is not necessary upon initial installation or periodic
calibration. In fact, for periodic calibration it is best for the electrode/sensor assembly to remain intact to minimize the possibility of
moisture or other contamination from entering the electrical interconnection area.
1. Reset the 2750 pH/ORP Sensor to factory calibration. With no electrode connected to the Sensor, press and hold the button until the
LED comes on steady then goes off again (approx. 10 seconds). When the LED goes off, release the button; reset is complete.
2. Connect an electrode to the 2750 pH/ORP Sensor.
3. Place the electrode/sensor assembly into a calibration solution as follows: (If the electrode is “healthy”, then the 2750 will
automatically recognize the solution, so the order in which the operator selects solutions for calibration is of no consequence.)
• For pH calibration, use any two of these international standards: pH 4.0, 7.0 or 10.0 buffer solutions.
• To produce standards for ORP calibration, mix the chemical Quinhydrone into pH 7.0 and 4.0 buffers to saturation (1/8g per 50ml).
• Regardless of the size of the container used for calibration, one inch of solution is adequate to completely submerge the tip of the
electrode.
• Allow at least 30 seconds for the electrode response to stabilize.
4. Press and hold the button for approximately 8 to 10 seconds. During this time, the LED will come on steady then go back off. (If the
LED blinks several times rapidly, the calibration was not successful. See the troubleshooting section.)
5. Remove the electrode/sensor assembly from the first calibration solution, rinse the electrode with tap water or DI water, and place it in
a second solution. Allow at least 30 seconds for the electrode response to stabilize.
6. Press and hold the button for approximately 8 to 10 seconds. During this time, the LED will come on steady then go back off. (If the
LED blinks several times rapidly, the calibration was not successful. See the troubleshooting section.)
7. Calibration is complete; return the unit to service.
‡ SIGNET 2750 pH/ORP Sensor
page 7 of 8
Troubleshooting
LED and Output Condition
Possible Causes
Suggested Solutions
Current Out:
LED off, current output is
3.6 mA
S3L: Temp out is +999.9
• No electrode installed
• Install electrode
• Bad/dirty contacts between electrode
and 2750
• Check interconnection between electrode
and 2750, clean contacts
During Local EasyCal, the LED
blinks rapidly for 4 seconds.
The current output is frozen at
some value.
• The buffer solution is outside of the
accepted tolerance for the 2750
• The electrode is depleted (> 1.1 pH or
65 mV offset)
• pH system: Use fresh 4 pH, 7 pH, or 10 pH
buffer and restart the calibration.
• ORP system: Use fresh 4pH and 7 pH buffer
solution saturated with quinhydrone.
• Replace the electrode.
Ordering Information
Mfr. Part No.
3-2750-1
3-2750-2
3-2750-3
3-2750-4
Code
159 000 744
159 000 745
159 000 746
159 000 842
Description
In-line Sensor Electronics w/Junction Box
In-line Sensor Electronics w/Jct. Box & Local EasyCal
Submersible Sensor Electronics with 15 ft. cable, 3/4 in. NPT threads
Submersible Sensor Electronics with 15 ft. cable, ISO 7-1/R 3/4 threads
3-2754
3-2754-HF
3-2755
3-2756
3-2756-DI
3-2757
159 000 747
159 000 748
159 000 749
159 000 750
159 000 751
159 000 752
Flat pH Electrode
Flat pH Electrode, HF Resistant
Flat ORP Electrode
Bulb pH Electrode
Bulb pH Electrode, DI Resistant
Bulb ORP Electrode
Accessories
Mfr. Part No.
3-8050-1
3-8050-2
3-8052-1
3-8052-2
3-2759
3-2759.391
3-2759.393
3-0700.390
P31515-0P200
P31515-0C200
P31515-0V200
5523-0322
Code
159 000 753
159 000 754
159 000 755
159 000 756
159 000 762
159 000 764
159 000 765
198 864 403
159 000 630
159 000 631
159 000 459
159 000 761
Description
Universal Mount Junction Box
Universal Mount Jct. Box w/Local EasyCal
3/4” NPT Mount Junction Box
3/4” NPT Mount Jct. Box w/Local EasyCal
pH/ORP Simulator/System tester
Adapter cable for use with 2750
Adapter cable for use with 2720
pH Buffer Kit
Universal Pipe Adapter PVC
Universal Pipe Adapter CPVC
Universal Pipe Adapter PVDF
Cable, 3-conductor shielded 22AWG (per ft)
‡ SIGNET
Signet Scientific Company, 3401 Aerojet Avenue, El Monte, CA 91731-2882 U.S.A. • Tel. (626) 571-2770 • Fax (626) 573-2057
For Worldwide Sales and Service, visit our website: www.gfsignet.com • Or call (in the U.S.): (800) 854-4090
GEORGE FISCHER +GF+ Piping Systems
3-2750.090/(B-8/01) English
page 8 of 8
© Scientific Company 2001
Printed in U.S.A. on Recycled Paper
‡ SIGNET 2750 pH/ORP Sensor