Starting at $861.00 Starting at $774.90



  • Large auto-sensing backlit display
    • Dial-type digital bar graph
  • 1/4 DIN enclosure
  • Selectable error mode for current outputs
  • Digital (S³L) input
  • AC frequency input
    • 0.5 to 1500Hz range
    • 0.5% of reading accuracy
  • 4-20mA input capable
    • With optional 8058 converter accessory
  • Warning LED indicator
  • Custom 13-character label capabilities for channel type
  • CE, UL, CUL, FCC & RoHS compliant
This is a replacement for the GF Signet 8750 pH/ORP Transmitter.


The GF Signet 9900 transmitter provides a single channel interface for many different parameters including Flow, pH/ORP, Conductivity/Resistivity, Salinity, Pressure, Temperature, Level and other sensors that output a 4 to 20 mA signal. The extra large (3.90" x 3.90") auto-sensing backlit display features "at-a-glance" visibility that can be viewed at 4-5 times the distance over traditional transmitters. The highly illuminated display and large characters reduce the risk of misreading or misinterpreting the displayed values. The display shows separate lines for units, main and secondary measurements as well as a "dial-type" digital bar graph.

The 9900 is offered in both panel or field mount versions. Both configurations can run on 12 to 32 VDC power (24 VDC nominal). The 9900 can also be loop powered with compatible sensors.

Designed for complete flexibility, plug-in modules allow the unit to easily adapt to meet changing customer needs. Optional modules include Relay, Direct Conductivity/Resistivity, H COMM and a PC COMM configuration tool. The unit can be used with default values for quick and easy programming or can be customized with labeling, adjustable minimum and maximum dial settings, and unit and decimal measurement choices.

9900 Transmitter Applications:

  • Wastewater treatment
  • Reverse osmosis
  • Deionization (ultra pure water, two bed system, mixed bed system)
  • Chemical manufacturing / addition
  • Metal and plastic finishing
  • Fume scrubber
  • Cooling towers
  • Media filtration


Plug-In Modules

Power Supplies

Mounting Bracket


Please consider these optional accessories.


Here's how some of our customers use this product...

RO Water Monitoring System

The Background: Our customer is a water treatment plant that uses reverse osmosis to remove contaminants from drinking water. They seek a way of ensuring treated water stays within a specified conductivity range as electrical conductivity is a key indicator of the RO quality and health of the RO system.

The Problem: The customer wants a control system that will prevent water with a conductivity above 200uS/cm from mixing with water that is compliant.

The Solution: We recommended a GF Signet 9900 Transmitter paired with a GF Signet 2819 Conductivity Electrode and actuated ball valve. The 9900 utilizes input from the 2819 and controls the ball valve with the help of a relay module that plugs into the back of the 9900.

The 9900 has both setpoint and hysteresis functions and so when the transmitter measures RO water above 200uS/cm, the ball valve will shut to prevent this out-of-compliance water from mixing with the known good product storage. The relay module mentioned earlier has two SPDT relays and only one is required to open/close the valve while the second relay can be used to alarm the workers. The workers can shut down the pumps/process and investigate the issue. Once the 9900 senses RO water below 190uS/cm it will automatically open the valve again for normal operation.

In Stock

Part Number Mounting Style Price Available
Field mount
$774.90 23 in stock
Panel mount
$774.90 16 in stock

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