Process Pro Signet 8750 pH / ORP

The SIGNET 8750 pH/ORP Transmitter is designed for broad application and ease of setup and use. The unit auto-configures for either pH or ORP use when connected to +GF+SIGNET pH or ORP sensors. Multiple mounting options allow for installation best suited to your particular application. The automated "Easy-cal" menu features automatic buffer recognition for mistake proof pH or ORP sensor calibrations. Two-line LCD provides sensor diagnostic information for ease in system maintenance.

These user friendly flowmeters provide a convenient way to display pH and temperature or ORP and temperature or mVolt and temperature.  Optional relays provide control for adjustment or alarms.   Optional dual input device is also available.

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  • Display in Deg. C or Deg. F
  • Hold and Simulate functions
  • Integral or remote mounting
  • Relay options
  • Output scalability
  • Dual output option allows temperature and pH signal transmission
  • 2 x 16 character dot matrix LCD
  • Chemical resistant enclosure and self-healing window
  • Large pushbuttons
  • Clearly marked terminal labels


  • Neutralization systems
  • Heavy metals recovery
  • Plating control
  • Scrubber control
  • Pool and spa control
  • Water treatment
  • Water quality monitoring
  • Disinfecting
Rating: NEMA 4X/IP65 front
Case: PBT
Window: Polyurethane coated polycarbonate
Keypad: Sealed 4-key silicone rubber
Weight: Approx. 325g (12 oz.)
Operating temperature: -10 to 70C (14 to 158F)
Storage temperature: -15 to 80C (5 to 176F)
Relative humidity: 0 to 95%, non-condensing

Accuracy: 0.03 mA at 25C, 24 V

Compatible electrodes:

Alphanumeric 2 x 16 LCD
Update rate: 1 second
Contrast: User selected, 5 levels

Standards and Approvals
CSA, CE, UL listed
Manufactured under ISO 9001

Sensor input range:
  • pH: 0.00 to 14.00 pH
  • temp. 3K Balco, -25 to 120C (-13 to 248F)
  • ORP: -1000 to +2000 mV, isolated (10K I.D. resistance T+, T-)

Current output:
4 to 20 mA, isolated, fully adjustable and reversible
Power: 12 to 24 VDC 5%, regulated

Relay output:
Mechanical SPDT contacts: Hi, Lo, Pulse, Off

Maximum voltage rating: 5 A at 30 VDC, or 5 A at 250 VAC resistive load

Max loop impedance: 50 ohms max. at 12 V, 325 ohms max. at 18 V, 600 ohms max. at 24 V

Update rate: 0.5 seconds

Hysteresis: User-adjustable

Max 400 pulses/min. Open-collector output: Hi, Lo, Pulse, Off

Open-collector, optically isolated, 50 mA max, sink, 30 VDC max. pull-up voltage.

Max 400 pulses/min.


The transmitter is available in a panel mount or a field version. The field version is mounted to the sensor using the integral mount kit (3-8051) or you may select the universal mount kit (3-8050) to mount the transmitter on a surface near the sensor.

All panel mount transmitters (3-8750-xx) include a mounting bracket and gasket for a NEMA 4X watertight panel installation. Panel mount transmitters fit into a standard 1/4 DIN panel cutout.

The Integral Mount Kit (3-8051) can be ordered separately and includes a conduit base, locking ring, and integral adapter for mounting the transmitter and sensor directly in a pipe.

The Universal Mount Kit (3-8050) can be ordered separately and includes a conduit base, locking ring, and universal adapter for mounting the transmitter on a pipe, wall, or other stationary surface.

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Ordering Information and Instruction Sheets (in PDF file)

Mfr. Part No. Code PDF file Description
3-8750-1 159-000-053 8750-1 pH/ORP transmitter Field mount
3-8750-1P 159-000-054 pH/ORP transmitter Panel mount
3-8750-2 159-000-055 8750-2 pH/ORP transmitter Field mount with relays
3-8750-2P 159-000-056 pH/ORP transmitter Panel mount with relays
3-8750-3 159-000-057 8750-3 pH/ORP xmtr Field mount with dual input/output
3-8750-3P 159-000-058 pH/ORP xmtr Panel mount with dual input/output

Sensors            pH sensors      ORP sensors

All signet flow sensors are compatible with 8550 or 8551 (except when using integral kit).

Mfr. Part No. use with  Description
3-8510-P0 8551 integral kit polypro/titanium 1/2" to 4"
3-8510-P1 8551 integral kit polypro/titanium 5" to 8"
3-8510-V0 8551 integral kit PVDF/Hastelloy 1/2" to 4"
3-8510-V1 8551 integral kit PVDF/PVDF 1/2" to 4"


Mfr. Part No. Code Description
3-8050 159-000-184 Universal mounting kit
3-8050.395 159-000-186 Transmitter NEMA 4X rear cover
3-8051 159-000-187 Flow Integral kit Mnt NPT
3-8050.396 159-000-617 RC Filter kit (for relay use)

Dimensions and wiring of ProcessPro Units - Field & Panel

Engineering Specifications
The transmitter shall be manufactured under ISO 9001 certified processes.
The transmitter shall be field or panel mountable.
The transmitter shall display pH, mV and temperature.
The display units shall be fully scaleable.
The device shall meet NEMA 4X and IP65 standards.
The operating voltage shall be 12 to 24 VDC.
The transmitter shall have a 4 to 20 mA output with an open collector output, 5 to 30 VDC or a 4 to 20 mA output with 2 relays, or dual 4 to 20 mA outputs with dual open collector capability.
The transmitter shall have security code capability.
The transmitter shall have simulate capability.
The transmitter shall hold an output value while calibrating.
The transmitter shall be +GF+SIGNET, Model 8750 pH/ORP Transmitter.

This unit has replaced the Compac Series 8710 - information

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