Signet Conductivity and Resistivity Instruments


The SIGNET 8850 Conductivity/Resistivity Transmitter is designed for broad application and ease of setup and use. The unit can be used for conductance, resistance, or TDS signal transmission and display. Mounting can be accomplished in several options best tailored to your application requirements. Full-microprocessor based electronics allow wide operating range range, and long term signal stability due to the elimination of potentiometers, jumpers and dip switches.  Update - Signet 8850-1P, 8850-1, 8850-2P, and 8850-2 are obsolete as of 2013.  They have been replace by Series 9900 transmitters that offer easy to read displays and extended versatility.  See Series 9900  The dual input 8850-3 is still in production.

Sensors for Signet conductivity transmitters.

Conductivity / Resistivity sensors are designed to provide versatile installation and accurate sensing across a broad dynamic range.  Accuracy of +/-2% for reading range and temperature indication using a Platinum RTD sensor.  Standard material is 316SS with options of titanium, Hastelloy C and Monel.  Easily mounts with 3/4" NPT fitting inline or couplings for submersible installations.  

Download specifications or installation manual for 2819 - 2823 sensors.  Sensor for sanitary applications are also available in stainless or titanium - contact KTH Sales

Range S Model Prices example of range
0.055 to 100 (18.2Mohm-10Kohm) 3-2819 $ 310.00 DI water to bottled water
1 to 1000 (0.5 -500 ppm) 3-2820 $ 310.00 rinse water to drinking water
10 to 10,000 (5 - 5,000 ppm) 3-2821 $ 310.00 drinking water
100 to 200,000 (50-100,000 ppm) 3-2822 $ 517.00 bottled water to chemicals
200 to 400,000 (100-200,000 ppm) 3-2823 $ 614.00 waste water to chemicals

 All signet above sensors are compatible 8860, 5800CR, 5900 and  8850 (except when using integral kit).  Also compatible with 3-9900-1P when supplied with 3-9900.394 module. 


PEEK Body Sensors with dual threaded connections for water applications.  Style 2839, 2840, 2841 and 2842 provide a compact design ideal for submersible or inline piping. The upper 3/4" thread is used for submersible with the lower 3/4 NPT thread for inline piping.  All feature a triple orifice flow-through design to minimize clogging and bubble entrapment.

Download specifications 

Range S Model Prices example of range
0.055 to 100 (18.2Mohm-10Kohm) 3-2839 $ 269.00 DI water to bottled water
1 to 1000 (0.5 -500 ppm) 3-2840 $ 269.00 rinse water to drinking water
10 to 10,000 (5 - 5,000 ppm) 3-2841 $ 269.00 drinking water
100 to 200,000 (50-100,000 ppm) 3-2842 $ 363.00 bottled water to chemicals

Above are compatible with 8850, 8860, 5800CR and 5900 instruments.  Also compatible with 3-9900-1P when supplied with 3-9900.394 module. 


These user friendly transmitters provide a convenient way to display conductivity / resistivity or temperature.  Optional relays provide control for adjustment or alarms.   Optional dual output device is also available.

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  • Display in microS, mS, kohm, Mohm, ppm (TDS)
  • Simulate function
  • Programmable Temperature compensation
  • Relay options
  • Dual output option allows temperature and process signal transmission
  • 2 x 16 character dot matrix LCD
  • Chemical resistant enclosure and self-healing window
  • Large pushbuttons
  • Clearly marked terminal labels


  • RO/DI system control
  • Rinse tank control
  • Cooling tower, scrubber or blowdown control
  • Environmental study (TDS)
  • Desalination monitor
  • Water quality monitoring
  • Leak detection
  • Chemical concentration
Compatible electrodes: +GF+ SIGNET 3-28XX-X Standard and Certified (NIST) Series Conductivity/Resistivity Electrodes
Accuracy: 2% of reading
Rating: NEMA 4X/IP65 front
Case: PBT
Window: Polyurethane coated polycarbonate
Keypad: Sealed 4-key silicone rubber
Weight: Approx. 325g (12 oz.)
Alphanumeric 2 x 16 LCD
Contrast: User selected, 5 levels

Operating temperature: -10 to 70C (14 to 158F)
Storage temperature: -15 to 80C (5 to 176F)
Relative humidity: 0 to 95%, non-condensing

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

Sensor input range:
Conductance: 0.055 to 400,000 microS
Resistivity: 10 Kohm to 18.2 Mohm
TDS: 0.023 to 200,000 ppm
Temperature: PT 1000, -25 to 120C (-13 to 248F)
Current output:
4 to 20 mA, isolated, fully adjustable and reversible
Power: 12 to 24 VDC 5%, regulated
Max loop impedance: 50ohms max. at 12 V, 325ohms max. at 18 V, 600 ohms max. at 24 V
Update rate: 0.5 seconds
Accuracy: 0.03 mA at 25C, 24V
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
Hysteresis: User-adjustable
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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Integrally mount conductivity transmitters- mounting tips

Ordering Information and Instruction Sheets (in PDF file)  - Note 8850-1 and 8850-2 are obsolete as of 1-2013.

Mfr. Part No. Code PDF file Description Prices
3-8850-1 159-000-228 8850-1 Conductivity/Resistivity transmitter Field mount n/a
3-8850-1P 159-000-229 Conductivity/Resistivity transmitter Panel mount
3-8850-2 159-000-230 8850-2 Conductivity/Resistivity transmitter Field mount with relays n/a
3-8850-2P 159-000-231 Conductivity/Resistivity transmitter Panel mount with relays
3-8850-3 159-000-232 8850-3 Conductivity/Resistivity Field mount with single input/dual output $ 791.00
3-8850-3P 159-000-233 Conductivity/Resistivity Panel mount with single input/dual output


8860 dual channel input - Description 



Mfr. Part No. Code Description
3-8050 159-000-184 Universal mounting kit
3-8050.395 159-000-186 Transmitter NEMA 4X 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 microS, mS, Kohm, Mohm, ppm (TDS).
The display units shall be fully scaleable without jumpers, pots or switches.
The transmitter allows for certified cell entry traceable to NIST.
The device shall meet NEMA 4X and IP65 standards.
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 with source selection (conductivity, resistivity or temperature) capability.
The transmitter shall be programmable for temperature compensation, cell constants and TDS factors.
The transmitter shall have security code capability.
The transmitter shall have simulate capability.
The transmitter shall be +GF+SIGNET, Model 8850 Conductivity/Resistivity Transmitter.

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