Keco Engineered Controls: Process Control Instrumentation
Liquid Analysis > Sensors > Rosemount 3900 Sensor

Rosemount 3900 Sensor

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3900 and 3900VP sensorThe Rosemount 3900 and 3900VP sensors provide you with extended sensor life by using crack-resistant glass and a double junction reference to protect against poisoning ions like chlorine, cyanides, sulfides, or ammonia. The sensors also have a built-in solution ground to provide advanced sensor diagnostics.


As a result, highly-durable Rosemount pH/ORP sensors can provide accurate measurements of pH and oxidation reduction potential in many aqueous solutions. These sensors are typically installed on open or closed tanks, pipelines, or holding ponds. The Rosemount 3900 sensor is provided with an integral cable connection, while the Rosemount 3900VP is equipped with a Variopol (VP8) connector. The Variopol connector enables the cable to be removed from the sensor for sensor service or replacement without removing the cable wire connections from the analyzer.

3900 with jet spray cleanerConstructed of a robust, chemical-resistant polyphenylene sulfide Ryton® plastic body, and using a Pt-100 resistance temperature device (RTD) for temperature compensation, these combination sensors offer a temperature range of 158 degrees F to 14 degrees F for liquids with low freezing points, making them equipped for reliable performance in harsh manufacturing or processing environments. Common applications for Rosemount 3900/3900P sensors include water treatment plants, beverage production facilities, water quality control in manufacturing, and more. KECO Controls recently installed Rosemount 3900 sensors in a commercial laundry wastewater monitoring system, to help monitor the pH of their wastewater before sending it off to a treatment facility. 


3900 low flow panel A SMART preamplifier option enables automatic recognition of the pH sensors by Rosemount 56, 1056, 1066, and 1057 transmitters. The pH calibration data is stored in this sensor, letting you calibrate before installation. This versatility allows for true “plug and play” sensor installations in the field. Amazingly the standard 3900 pH sensor can also measure pH in demineralized water without a flowing reference when used in a Rosemount low-flow cell panel.


Companies with more difficult application requirements may opt for the heavy-duty Rosemount 396 pH/ORP sensors when dealing with dirty, abrasive, coating, and high solid applications. These sensors are also highly configurable for several installation requirements. Please see the Rosemount 396 pH/ORP sensor product data sheet for more details on these sensors. 

Rosemount 396 Ph Orp Sensor

Keco Engineered Controls is a trusted distributor of Emerson Rosemount process control instrumentation. Keco provides a wide selection of products from Rosemount Measurement and the Rosemount Analytical Liquid and Gas Divisions. These products are used in operations like electric and steam power plants, chemical processing plants, food and beverage production, oil and gas terminals, hospital boiler operations, and pharmaceutical production plants.  Please see the Rosemount 3900 Manual for product specifications. For more information on installation and use, call or email us at 732-901-5900;


To find out more about this product, please also see our Pressure page, or contact us.