Hello. I’m Linda Meyers – the senior pH product manager at Emerson Rosemount. According to our most recent market survey, the new Model 3900 pH and ORP sensor is one of the most widely accepted general purpose sensors in the history of Rosemount Analytical. We set out to discover what makes customers choose this sensor for so many applications – here’s what some of our customers said:
The sensor provided one customer with “easy installation of the Model 3900.” With the newly styled body with ¾ inch and 1 inch threads, the sensor is very easy to install into the process. In addition to the newly styled body, the version with the VP plug is even easier to use because once the cable is secured, the sensor can be replaced by simply unplugging it from the mating cable and plugging in a new sensor. In fact, another one of our customers stated that they were extremely happy with its ease of use and described it as a “plug-in -and-play.” The VP connector system is such a great way to install pH and other sensors; does your facility take advantage of the VP connector cables for the ease of the “plug and play” feature?
Some customers commented that they were appreciative of the online wiring diagrams available. The wiring diagrams have actually been available for all of our pH and ORP sensors for some time, but due to the overwhelming requests for this new sensor, more and more users are becoming aware of our on-line wiring information where we keep all of our most recent drawings. Did you know that we had the on-line wiring diagrams at www.emersonprocess.com/raihome/sp/liquid/wiring?
One interesting side note; some of our customers have been trying out the 3900 in applications with low conductivity water with some amount of success. One customer used the sensor in 5 uS/cm water successfully although the sensor is only rated to be used in 100 uS/cm minimum. The recommended pH sensor for use in below 100 uS/cm applications is the 3200HP, but we are investigating the feasibility of the 3900 as another choice for certain lower conductivity applications. Are you interested in using a 3900 for lower conductivity liquids? And if so, what is the normal conductivity level of the liquid?
The Model 3900 is one of two general purpose, threaded pH and ORP sensors that Rosemount Analytical suggests for water and wastewater applications. The other sensor is the Model 389 which maximizes the sensor life in applications containing ammonia, sulfides and heavy metals. Did you know that we have other pH and ORP sensors to suit almost every in-service application? With so many pH and ORP sensors that Rosemount offers, we want to make finding the right sensor for your application easier than before. Want to know how we categorize these to make them easy to find?
General Purpose (water/wastewater) pH and ORP Sensors:
Models 3900 and 389 (and 385+)
Tough Application (High Temperatures & Aggressive Chemicals) pH and ORP Sensors:
Models PERpH-X and TUpH sensors
Special Process needs for high purity (<100uS/cm), non-glass, SIP, and HF service:
Models 3200HP, TF396, 3800/Hx338 and 372






