The chlorine level is measured based on the ORP or REDOX principle. An increase in the ORP value correlates with an increase in the free-chlorine level. pH and ORP testing are done together for efficient disinfection and control. The efficacy of sanitizers, such as chlorine, depends on a controlled pH value. The ORP value is the most consistent indicator of the sanitizing effectiveness of the pool or spa. Typically, 650-750 mV at 7.2 pH indicates proper water treatment. The controllers offer remote access and visualizing of measured data via Cloud connectivity. All measurements and main events are sent to Hanna Cloud through the Ethernet connection.
The BL131 controllers can be paired with the HI1036-18XX digital probe. The probe incorporates pH, ORP and temperature sensors along with a matching pin. It was specially designed to detect a broken electrode based on a shifted zero potential value, around 4 pH. The HI1036-18XX uses an Ag/AgCl reference with 3.5 M KCl. The ORP values are referenced to it. Measurement data stored on the probe is transferred to the controller via a digital connection; thus eliminating noise and static due to high impedance signals carried by the cable.
Main features:
• Two built-in peristaltic dosing pumps with Proportional control
• Manual control for pump priming
• Overfeed protection using overtime safety timer
• Resumes dosing on restart in case of power failure
• Level input to stop control without reagents
• Interlocked pH-ORP control (i.e. ORP control only runs when the pH set point has been reached)
• External dosing
• The controller has 2 relays that can be used to control larger external dispensing pumps, allowing the BL131 to be used in larger pools.
• Air temperature sensor
• Allows triggering an alarm if the air temperature is cold enough that there is a risk of water freezing in the pipes (e.g. hot tubs in winter with the circulation pump off)
• Bidirectional control
• User selectable logging interval
• As pool settings normally do not change that quickly, minimize data management by choosing from a wide selection of logging intervals
• Multicolored LED indicators for dosing, meter status and service
• Real-time graph display
• Programmable alarms
• Password protection
Multiple configurations:
BL13x swimming pool controllers are available in two configurations:
• in-line, for direct probe installation and chemical injection fittings into existing piping
• flow cell, for calibration and probe maintenance without having to shut down the recirculation pump
For compliance monitoring, each of the BL13x family has a built-in datalogger. Measurement reading intervals can be set at 30s/1m/5m/15m/30m/1h, with a new log starting new each day or when the instrument is calibrated. Logged data include pH, ORP, and temperature values, last calibration data, setup configuration, and any event data. The BL13x swimming pool controller is an automatic system, but it is advisable that users check the controller and verify pH and free‑chlorine levels (in mg/L or
ppm) in the pool using a portable colorimeter.