ORP (Chlorine) Dosing Consent Both pH and ORP meters are commonly used with swimming pools. With chlorine disinfection there is an inverse relationship between pH and ORP. As the pH level increases, the ORP level decreases. These controllers utilize a dosing consent feature that will not dose chlorine until the pH value is first corrected since it is possible to have a low ORP value even though there is sufficient chlorine. The dosing consent feature prevents waste of chemicals and avoids having a higher chlorine concentration level than desired. Acid and Chlorine Tank Level Inputs The controllers allow for a connection to an optional level controller. This input is used to disable the dosing pumps when there is no chemical left in the reservoir tank. Programmable Alarm System These controllers allow users to enable or disable the low and high level of alarms for all parameters: pH, ORP, and temperature. When an alarm is activated, all dosing will stop. The alarm system also offers overdosing protection in that if the value is not corrected within a specified time interval then the meter will go into alarm status. Automatic Logging Measurement readings can be set at 30s/1m/5m/15m/30m/1h intervals. A new log is started each time the instrument is calibrated or at the start of a new day. Logged data includes pH, ORP, and temperature values, last calibration data, setup configuration, and any event data. Ethernet Port for Hanna Cloud Connectivity USB Connectivity Easily transfer data to a PC using a flash drive and the USB port. GLP Good Laboratory Practice (GLP) refers to a quality control function used to ensure uniformity of probe calibrations and measurements. GLP stores pH/ORP calibration information including date and time for pH/ORP sensors. Hold Input It is possible to connect a flow switch mounted in-line or a mechanical relay that is connected to the recirculation pump power source to the hold input of these controllers. With no flow or when no power is applied to the recirculation pump, the hold circuit will disable the dosing pumps. This will prevent any dosing of chemical when there is no movement of water in the system. Analog Outputs (BL131 only) The BL131 controller offer three 4-20 mA outputs. Each output can be disabled or connected to an external recording device. Each of the three measured parameters (pH, ORP, and temperature) can be assigned to an analog output where the current signal will be proportional to the measured value. For more flexibility and better resolution, the analog output can be scaled; users can define any two points within a parameter range to correspond to the analog output span. For example, the controller assigns 0 pH to 4 mA and 14 pH to 20 mA as a default. The user can adjust the pH range to assign pH 6 to 4 mA and pH 8 to 20 mA. This adjustment allows better resolution in the range of interest. Password Protected These controllers feature password protection that offers restricted access to calibration, setup, and review of logged data. The password can be set and enabled/disabled during general setup of the instrument. 15 Process Instrumentation 15.21 www.hannainst.com | controllers
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