GF Signet 2750 User Manual

Signet 2750 DryLoc® pH/ORP Sensor Electronics

English

*3-2750.090*

3-2750.090 Rev. K 01/13 English

1. Description

2. Specifi cations

SAFETY INSTRUCTIONS

1. Depressurize and vent system prior to installation or removal.

2. Confi rm chemical compatibility before use.

3. Do not exceed maximum temperature/pressure specifi cations.

4. Wear safety goggles or faceshield during installation/service.

5. Do not alter product construction.

6. When using chemicals or solvents care should be taken and appropriate eye,
face, hand, body, and/or respiratory protection should be used.

1. Description

Signet 2750 pH/ORP Sensor Electronics provide two-wire 4 to 20mA loop output for pH and ORP measurements, without the expense
of local display and other luxuries available in full-featured transmitters. Preamplifi cation is built-in, reducing system costs while ensuring
absolute signal integrity up to 305 m/1,000 feet.

3. In-line Installation

4. 2750 In-line Assembly

5. Submersible Installation

6. Digital (S

3

L) wiring

7. 4 to 20 mA Loop wiring

8. Calibration

9. Troubleshooting

10. Ordering Information

These sophisticated fi eld-mount devices also provide the Digital (S

3

L) output; the latest development in leading-edge technology from
Signet. The 2750 Sensor Electronics self-confi gure for pH or ORP operation via automatic recognition of electrode type, and the DryLoc
electrode connector quickly forms a robust assembly for submersible and in-line installations.

NEMA 4X Junction Boxes are integral parts of the in-line version and are available as accessories for the submersible version. The
optional EasyCal feature allows simple push-button calibration and includes an LED for visual feedback.

2. Specifi cations

General

• Compatible Electrodes: Signet DryLoc Electrodes.

(PT1000 temperature sensor versions for pH)

• Operational Range: 0.00 to 14.00 pH, ±2000 mV ORP
0 °C to 85 °C (32 °F to 185 °F)

• Response Time (includes electrode response):
pH: <6 s for 95% of change
ORP: application dependent
pH Temp T90: 200 s (2724)
132 s (2726)
438 s (2756-WT)

Materials:

2750-1, -2 (in-line): PBT (thermal plastic polyester)
2750-3, -4 (submersible): CPVC

Cable for -3, -4 submersible versions:
5 m (15 ft) 3-conductor shielded, 22 AWG

• May be extended up to 3.48 m (100 ft) with current output

• May be extended up to 3.48 m (100 ft) with (S

Weight:
2750-1, -2 (in-line): 0.75 kg (1.75 lb)
2750-3, -4 (submersible): 0.64 kg (1.4 lb)

Environmental

• Ambient Temp.: 0 °C to 85 °C (32 °F to 185 °F

• Storage Temp.: -20 °C to 85 °C (-4 °F to 185 °F)

• Relative Humidity: 95% max, non-condensing

• Immunity: EN50082-2

• Emissions: EN50081-1

• Enclosure Rating:
2750-1, -2 (in-line): NEMA 4X/IP65 (with electrode connected)
2750-3, -4 (submersible): NEMA 6P/IP68 (with electrode and
watertight extension pipe connected)

Electrical

• Input Impedance: >10

• Input response time: 500 ms

• Temperature drift: ±0.002 pH per ºC
±0.1 mV ORP per ºC

• Input resolution: 0.02 pH, 1 mV ORP, 0.3 ºC

11

Ω

3

L) output

Current output:

• Description: pH: Fixed 4 to 20 mA, isolated,
0 to 14 pH (custom scaling available)
ORP: Fixed 4 to 20 mA, isolated,
–1000 to 2000 mV (custom scaling
available, –2000 to 2000 mV)

• Power: Regulated 12-24 VDC ± 10%,
20 mA max.

• Max Loop Resistance: 50 Ω max. @ 12V
325 Ω max. @ 18V
600 Ω max. @ 24V

• Accuracy: ±32 μA @ 25 ºC

• Temperature drift: ±1 μA per ºC

• Output resolution: ± 5 μA

• Error indication: 3.6 mA

3

Digital (S

• Description: Serial ASCII, TTL level 9600 bps

• Power: 5 VDC ± 10% regulated, 3 mA max

• Accuracy: pH: ± 0.03 pH @ 25 °C
ORP: ± 2 mV @ 25 °C

• Resolution: pH: 0.01 pH
ORP: 1 mV
Temp. 0.2 °C

• Error indication: Temp output "+999.9"

Standards and Approvals

• CE

• Manufactured under ISO 9001 for Quality, ISO 14001 for
Environmental Management and OHSAS 18001 for Occupational
Health and Safety.

China RoHS (Go to www.gfsignet.com for details)

Declaration of Conformity according to FCC Part 15
This device complies with Part 15 of the FCC rules. Operation is

subject to the following two conditions:
(1) This device may not cause harmful interference, and,
(2) This device must accept any interference received,

including interference that may cause undesired operation.

L) output:

3. In-line Dimensions

• The 2750-1 in-line sensor (without EasyCal) is designed for applications where electrode calibration is facilitated by remote
equipment.

• The 2750-2 In-Line sensor includes EasyCal.

• A Signet installation fi tting (1/2 in. to 4 in.) or a Signet pipe adapter is required to secure the electrode in the pipe.

• The Signet Measurement and Instrumentation catalog offers a complete selection of fi ttings.

• The 2750-3 and 2750-4 submersible sensor electronics are recommended for in-line applications using the 2764 series differential
electrodes and the 2774 series Threaded DryLoc electrodes.

• 2764 and 2774 series electrodes thread directly into standard 1 in. or 3/4 in. NPT fi ttings.

115 mm
(4.5 in.)

89.4 mm
(3.52 in.)

248 mm

(9.75 in.)

Lubricate O-rings
with a non-petroleum
based, viscous lubricant
(grease) compatible
with the system.

Lubricate O-rings
with a non-petroleum
based, viscous lubricant
(grease) compatible
with the system.

94 mm

3.7 in.

178 mm

(7 in.)

140 mm

5.5 in.

Mounting position

2764 series electrodes must be mounted upright.

• Vertical (0°) position optimum

• Do not install within 30º of horizontal (Contact factory for horizontal or inverted installation requirements.)

• Recommended maximum fl ow rate 10 ft/s.

• Wet-tap electrodes, 2724, and 2774 series electrodes can be mounted at any angle.

45 mm

(1.75 in.)

Lubricate O-ring
with a non-petroleum
based, viscous lubricant
(grease) compatible
with the system.

OK

YES

Vertical ± 60°

NO

YES

OK

OK

30°

NO

OK

30°

NO

2

OK OK

OK

OK

OK

OK

OK

OK

Signet 2750 DryLoc pH/ORP Sensor Electronics

4. 2750 In-line pH Sensor Assembly

Note: This procedure applies to systems using standard 2724-2726 electrodes. If the 3719

pH/ORP Wet-Tap is used, refer to the 3719 manual for instructions.

1. Insert electrode into Signet installation fi tting. Seat the

electrode tabs into the alignment notches in the fi tting.

Lubricate O-rings
with a non-petroleum
based, viscous lubricant
(grease) compatible
with the system.

2. Thread the in-line retaining nut onto fi tting to secure the electrode

Retaining nut

into place.

HAND-TIGHTEN THE THREADED NUT ONTO THE INSTALLATION
FITTING. DO NOT USE TOOLS! DO NOT USE THREAD SEALANT OR
LUBRICANTS ON THE FITTING THREADS OR THE SENSOR CAP.

Chemical Compatibility Warning

The retaining nuts of pH and ORP sensors are not designed for prolonged contact with
aggressive substances. Strong acids, caustic substances and solvents or their vapor may
lead to failure of the retaining nut, ejection of the sensor and loss of the process fl uid with
possibly serious consequences, such as damage to equipment and serious personal injury.
Retaining nuts that may have been in contact with such substances e.g. due to leakage or
spilling, must be replaced.

Note:

Keep the electrical interconnection between electrode and sensor
electronics dry and clean at all times.

3. Unlock the ring on base of 2750 (The ring is unlocked when the

lines on the ring and body of the 2750 are not aligned.)

Locking Ring

LUBRICATE O-RINGS WITH A NON-PETROLEUM BASED, VISCOUS
LUBRICANT (GREASE) COMPATIBLE WITH THE SYSTEM.

Unlocked

The molded alignment
marks are enhanced
for clarity.

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.)

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.

Signet 2750 DryLoc pH/ORP Sensor Electronics

The molded alignment
marks are enhanced
for clarity.

Locked

CAUTION!

• Do not remove the electrode from a pressurized pipe.

• Wear appropriate protective clothing when working
with chemicals in pressurized pipe.

3